PfEMP1, an antigen involved in malaria pathogenesis, on the surface of HbC infected erythrocytes together with the observation of reduced cytoadhesion of parasitized erythrocytes and impaired rosetting in vitro. We investigated the impact of this hypothesis on the development of acquired immunity against Plasmodium falciparum variant surface antigens (VSA) encoding PfEMP1 in HbC in comparison with HbA and HbS carriers of Burkina Faso. We measured: i) total IgG against a single VSA, A4U, and against a panel of VSA from severe malaria cases in human sera from urban and rural areas of Burkina Faso of different haemoglobin genotypes ; ii) total IgG against recombinant proteins of P. falciparum asexual sporozoite, blood stage antigens, and parasite schizont extract; iii) total IgG against tetanus toxoid. Results showed that the reported abnormal cell-surface display of PfEMP1 on HbC infected erythrocytes observed in vitro is not associated to lower anti- PfEMP1 response in vivo. Higher immune response against the VSA panel and malaria antigens were observed in all adaptive genotypes containing at least one allelic variant HbC or HbS in the low transmission urban area whereas no differences were detected in the high transmission rural area. In both contexts the response against tetanus toxoid was not influenced by the β-globin genotype. These findings suggest that both HbC and HbS affect the early development of naturally acquired immunity against malaria. The enhanced immune reactivity in both HbC and HbS carriers supports the hypothesis that the protection against malaria of these adaptive genotypes might be at least partially mediated by acquired immunity against malaria.A recently proposed mechanism of protection for haemoglobin C  links an abnormal display of  Plasmodium falciparum malaria PfEMP1, an antigen involved in malaria pathogenesis, was reported in vitro. On this basis it has been proposed that HbC protection might be attributed to the reduced PfEMP1-mediated adherence of parasitized erythrocytes in the microvasculature. Given the reported observations, it could be hypothesized that HbC carriers may develop an altered immune response to PfEMP1. Intriguingly, an enhanced immune recognition of variant surface antigens (VSA) was initially observed in HbAS individuals by Marsh et al., Red blood cell disorders including haemoglobin variants and thalassaemias provide with their unusually high prevalence and distribution in malaria endemic areas PfEMP1 in individuals belonging to the Mossi ethnic group carrying different β-globin genotypes  living in urban and rural areas of Burkina Faso, West Africa by measuring: i) total IgG against a single VSA (variant surface antigen), A4U, and against a panel of VSA from severe malaria cases; ii) total IgG against recombinant proteins of P. falciparum sporozoite (CSP), blood stage  antigens, parasite schizont extract, and iii) total IgG against a non malaria antigen, tetanus toxoid.The coexistence of HbC and HbS in a hyperendemic malaria context such as Burkina Faso provided a unique opportunity to explore this question in a comparative approach. In the present study, we compared the humoral response to Plasmodium falciparum genotyping of glurp was carried out according to a standard protocol Healthy individuals belonging to the Mossi ethnic group of Burkina Faso were recruited after oral informed consent was obtained during the dry seasons 2005/2006 at the “Centre Medical Saint Camille” of the capital city Ouagadougou, and in the villages nearby  of the Kadiogo district, as described in i) a reference isolate A4U, derived by sequential selection for binding to the monoclonal antibody BC6, which is specific to the expressed A4U var gene, resulting in a population of infected erythrocytes expressing predominantly one specific PfEMP1 variant on their surface, A4U PfEMP1 ii) a composite isolate (CI) derived by pooling a panel of wild isolates obtained from children presenting to the wards of Kilifi district hospital in Kenya with malaria at high parasitemia (T.H and T.N.W unpublished data).Antibody responses against the parasite infected-erythrocyte surface antigens were tested using the method with modifications of Williams et al. Mature trophozoite stage parasitized RBC (pRBC) at between 3–5% parasitaemia were thawed from frozen culture using saline solutions according to a gradient from 12% to 0.9% in a suspension at 50% haematocrit with buffer (0.5% BSA/PBS). 1 µl of serum was pipetted into separate wells of a 96-well U-bottomed plate  to which was added 11.5 µl of the infected pRBC cell suspension in 0.5%BSA/PBS and 10 µg/ml of ethidium bromide. The mixture was incubated at room temperature for 30 min, following which the cells were washed three times with 0.5%BSA/PBS, centrifuging at 1000 rpm for 3 min per wash. The cells were then re-suspended in 50 µl 0.5%BSA/PBS containing a 1:50 dilution of sheep anti-human γ chain (FITC) fluorescein isothiocyanate-conjugated antibody (The Binding Site) was added to each well. A further incubation at room temperature in darkness, for 30 min was carried out, after which, following a further series of washes, at least 1000 pRBC were counted on an EPIC/XL flow cytometer . The Mean Fluorescence Intensity (MFI) was defined as the difference between the geometric mean of the fluorescence emitted by trophozoite pRBC and the geometric mean of the fluorescence emitted by the non pRBC. Non-specific recognition as measured by European negative controls was subtracted by the MFI of tested individuals.P. falciparum  and several blood stage antigens: full length 3D7 allele of AMA-1 , Wellcome allele of MSP-119 , Dd2 allele of MSP-2 , 3D7 allele of MSP-3 , Camp allele F2 domain of EBA-175 region II , and the Wellcome strain parasite schizont extract . When antigens were conjugated to GST or MBP, the optical density (OD) of GST or MBP for each sample was subtracted from that of the antigen to obtain the final OD. All assays were performed in Dynex Immunolon 4HBX ELISA plates (Dynex Technologies Inc). Wells were coated with 50 ng for all blood stage antigens (1 µg for CSP and PSE) in 100 µl of carbonate buffer , and incubated overnight at 4°C before washing four times in PBS/Tween . The plates were then incubated in 200 µl/well of blocking buffer (1% skimmed milk in PBS/Tween) for 5 hours at room temperature. Antigen-coated wells were washed and incubated overnight at 4°C with test sera (1/500 dilution) at 100 µl/well. Unbound antibody was washed off, and 100 µl of secondary antibody  diluted to 1/5000 in blocking buffer was added into each well and incubated for 3 hours at room temperature before detection with O-phenylenediamine . The reaction was stopped with 25 µl/well of 2M H2SO4. The absorbance was read at OD 492nm using the SPECTRAFluor program, (XFLUOR4 Version: V 4.11) and analysed using Excel (Microsoft). The coefficient of variation (CV) between duplicate wells was calculated in Excel (Microsoft) using the formula below to ensure accuracy: Enzyme linked immunosorbant assays (ELISA) were performed according to well established protocols No differences in the Mean Fluorescence Intensity (MFI) according to the haemoglobin genotype were detected when looking at urban and rural samples all together. Further comparisons were carried out separately with the urban and the rural samples due to the different EIR  and mean age of the two subsets whose characteristics are described in P. falciparum antigens tested by ELISA, with some degree of statistical significance as measured by Kruskal-Wallis test and pairwise T-test  are still under debate. A recently proposed mechanism suggested that the protection conferred by HbC may be attributed to the reduction of cytoadherence and impaired rosetting observed in relation to the altered display of PfEMP1 on HbCC erythrocytes ban area . Interes samples . These d samples , rather We believe that the discrepancy between results from urban and rural settings could be the consequence of saturated immunity in high transmission contexts. These observations emphasize the need, when studying candidates of genetic resistance/susceptibility to malaria and their underlying hypothesized mechanisms, to take into full account the epidemiological context as a potential confounder.Although this study can not conclusively validate any of the different functional mechanisms proposed to explain the protection of haemoglobin variants, a consistently enhanced immune reactivity in both HbC and HbS adaptive genotypes suggests the idea of a convergence in terms of their impact on the acquisition of immunity against malaria. It has been already shown that the model initially proposed for explaining G6PD protection, by enhanced phagocytosis of ring- parasitized altered erythrocytes, fits well also in the case of HbS and β-thalassemia


Attaran argues that five years into the Millenium Development Goals project, problems with measurement mean that often we cannot know if true progress towards these goals is occurring. In September 2000, 147 heads of state met at the United Nations (UN) headquarters—the largest such gathering ever—to resolve action on the most pressing problems of humanity and nature ). Details of the targets subsumed by goal eight and the various indicators for all the goals or targets can be found in .Goal 1: Eradicate extreme poverty and hunger • Reduce by half the proportion of people living on less than a dollar a day• Reduce by half the proportion of people who suffer from hungerGoal 2: Achieve universal primary education • Ensure that all boys and girls complete a full course of primary schoolingGoal 3: Promote gender equality and empower women • Eliminate gender disparity in primary and secondary education preferably by 2005, and at all levels by 2015Goal 4: Reduce child mortality • Reduce by two thirds the mortality rate among children under fiveGoal 5: Improve maternal health • Reduce by three quarters the maternal mortality ratioGoal 6: Combat HIV/AIDS, malaria, and other diseases • Halt and begin to reverse the spread of HIV/AIDS• Halt and begin to reverse the incidence of malaria and other major diseasesGoal 7: Ensure environmental sustainability • Integrate the principles of sustainable development into country policies and programmes; reverse loss of environmental resources• Reduce by half the proportion of people without sustainable access to safe drinking water• Achieve significant improvement in lives of at least 100 million slum dwellers, by 2020Goal 8: Develop a global partnership for development This September, the heads of state will gather again for the Millennium +5 Summit to assess the five-year progress of the MDGs. They will find that the MDGs have become all-important, not just within the UN, but also as the zeitgeist of the global development enterprise. As Professor Jeffrey Sachs, Director of the UN's Millennium Project, has declared, “To the extent that there are any international goals, they are the Millennium Development Goals”.But is it wise to elevate the MDGs to the pedestal where they now sit? Could it be, despite an appearance of firm targets, deadlines, and focused urgency, that the MDGs are actually imprecise and possibly ineffective agents for development progress?In this article, I argue that many of the most important MDGs, including those to reduce malaria, maternal mortality, or tuberculosis (TB), suffer from a worrying lack of scientifically valid data. While progress on each of these goals is portrayed in time-limited and measurable terms, often the subject matter is so immeasurable, or the measurements are so inadequate, that one cannot know the baseline condition before the MDGs, or know if the desired trend of improvement is actually occurring. Although UN scientists know about these troubles, the necessary corrective steps are being held up by political interference, including by the organisation's senior leadership, who have ordered delays to amendments that could repair the MDGs . In shorWhat makes the MDGs attractive is their concreteness. For example, the MDG to eradicate extreme poverty subsumes a “target” to “halve, between 1990 and 2015, the proportion of people whose income is less than $1 a day”, which in turn subsumes “indicators”, one of which is to measure income based on purchasing power.Knowing that, worldwide, 28% of people in 1990 had purchasing power below $1 a day gives rise to a benchmark: that in 2015, fewer than 14% of people should be so destitute . Currently, East Asia is on track; sub-Saharan Africa is not . Such deIt is harder to get sufficient and reliable data for the health MDGs. Even the most basic life indicators, such as births and deaths, are not directly registered in the poorest countries. Within this decade, only one African country (Mauritius) registers such events according to UN standards . WithoutAccordingly, most of the available data on the health MDGs come from methods of estimation, censuses, specialised household surveys, or all of these together.There are many—too many—household surveys. In the public-health field, the best known are the Demographic and Health Survey (DHS) and the Multiple Indicator Cluster Survey (MICS), funded mainly by the United States and United Nations Children's Fund (UNICEF), respectively . In addiDonor's [sic] support is not always appropriately coordinated. There are many examples of duplicated or conflicting data collection activities. This lack of coordination does not only causes [sic] a huge waste of funds, it also put [sic] a high burden on national statistics offices. In the past few years, significant progress has been made to identify synergies among different survey programs or to develop common questionnaire modules, and to conduct joint data collection activities. But there is certainly room for much more cooperation. All of this is true, but even within the UN, different agencies jostle counterproductively for data. For example, in 2002, the WHO launched a new World Health Survey in over 70 countries to compete with the longer-running DHS and MICS [10]. Justified as a “sound basis for evaluating progress towards the millennium development goals”, instead the WHO's new survey tied up the few qualified statistical staff in the poorest countries [11]. Three years later (at the time of going to press), the new project has yet to publish a single dataset. Yet household surveys are serviceable but crude tools. Even with a simple question, such as about a child's birth weight, people's answers only roughly approximate the truth, as would be measured by weighing on a scale [13]. Other survey questions are so technical that no layperson can answer them accurately. MICS, for example, asks parents if their child's anti-malaria bed net was “ever treated with a product to kill mosquitoes”: an accurate answer depends on the type, dose, and date of insecticide treatment, and whether the local mosquito species carry insecticide resistance genes [14]. Because household surveys do not announce these or other sources of error, one can easily have false confidence in them. For example, many MICS survey reports present their findings as single-point estimates, without any of the usual qualifiers of data inaccuracy or quality, such as statistical confidence intervals or significance tests .In short, there are many sources of data on the MDGs. When those sources suffice to reveal statistically significant trends in the MDGs, then all is well, and it is possible to make conclusive statements: that the MDGs are being met, or that the MDGs are being missed. But, as the case studies below illustrate, such certainty is highly elusive.MDG 6, Target 8, pledges to “have halted by 2015 and begun to reverse the incidence of malaria”. The malaria MDG overlaps with a somewhat earlier (1998) WHO-led goal known as Roll Back Malaria (RBM), which aims “to halve malaria-associated mortality by 2010 and again by 2015” [16]. Even though the MDG and the RBM goal are only quasi-consistent with one another, the UN allows them to coexist, and UN communications often mention both [16]. Accordingly, both are discussed here.Yet with double attention on malaria, and the head start afforded by RBM, the UN still is unable to make an official pronouncement on the progress of its malaria goals. The WHO and UNICEF write that it is “too soon to determine whether the global burden of malaria”, meaning both incidence and mortality, “has increased or decreased since 2000” [16].Too soon? RBM is in its seventh year, and past the halfway mark of its 2010 deadline. The only two possible reasons not to know if malaria has increased or decreased are that the UN either (i) did not encourage timely measurements or (ii) chose indicators—malaria incidence and mortality—that are essentially immeasurable.Actually, both are true. What follows is a cautionary history.In 2002, the British government commissioned an independent evaluation of the UN's malaria efforts. It did so because it was the largest financier of RBM, and because of a perception that there was insufficient alignment between the efforts of the UN agencies and malarious countries. On the subject of measuring progress, the evaluators wrote: The main problem affecting…data collection efforts…has been that an overly complex and insufficiently prescriptive approach has been taken. There has been a failure to clearly define goals and priorities of the [measurement] strategy at the global and regional levels....Too many indicators are proposed. Too many sources of data are suggested. Insufficient guidance is given to countries on data collection and methodology….Some countries are measuring one thing, some countries are measuring another….In some cases, data are being collected without any systematic and scientific sampling methodology, and so are essentially meaningless and impossible to interpret. [17]This unsparing criticism points to two problems, which although they pertain to RBM, often apply with equal force to the malaria and other MDGs. The first problem concerns the lack of a baseline: it is impossible to retrospectively measure worldwide  malaria incidence and mortality existing at the inception of the RBM goal or the MDG, when the data from that era are universally acknowledged to be poor [18]. Without knowing the original condition, it is futile to stipulate either “to halve” malaria mortality by 2010 or “to halt” malaria incidence by 2015. Such words have no meaning where the baseline is mysterious.The second problem concerns the unsuitability of the indicators: both malaria incidence and mortality are so crudely measured by household surveys and most countries' health records that, essentially, they are immeasurable. The UN's malaria monitoring group agrees, writing that “malaria-specific mortality should not be monitored routinely, as this can not be measured easily in malaria-endemic Africa” [19]. Yet the UN often ignores such warnings, even when they are timely, explicit, and the opinions of its own scientists. It was only two months after WHO scientists wrote that “it will not, in general, be possible to measure the overall incidence rate of malaria” that the UN chose the incidence rate as the mainstay of the malaria MDG [20].The legacy of unfortunate decisions now leaves malaria risk mapping as the only feasible way to estimate (not measure) malaria incidence and mortality. The principle is to superimpose a map of a population onto a map of malaria intensity, although, in practice, the limitations include malaria maps from the 1960s and too few demographic surveillance sites to accurately measure and calibrate incidence and mortality risks . The WHO has been slow to use risk mapping, probably because it fears public criticism when, inevitably, the current estimates of malaria severity must be revised upward .Accordingly, years after the withering external evaluation, the UN neither has achieved convincing measurement or estimation of malaria incidence and mortality, nor has it abandoned those as the key indicators of progress. Both the RBM goal and the malaria MDG are today immeasurable.MDG 5, Target 6, pledges to “reduce by three quarters, between 1990 and 2015, the maternal mortality ratio” . Both the number of such deaths and the number of births are used to calculate the maternal mortality ratio . However, it is exactly in the poorest countries where the maternal mortality problem is severest that the data about deaths and births are least satisfactory. Vital registration would help, but few developing countries, accounting for 24% of the world's live births, have complete data . DirectlTherefore MMR must be estimated. The current method is crude, and uses regression modelling based on partial vital registration, censuses, household surveys, and other inputs [27]. The outputs are a point estimate for MMR in each geographic region, surrounded by an educated guess  of the lower and upper range in which the point estimate could lie.Accordingly, the most recent (2000) published estimate for MMR worldwide is 400 maternal deaths per 100,000 births, within an unscientific, best-guess range of perhaps 210 (low) to 620 (high) [28]. Estimates for the MDG baseline year (1990) are similarly vague [29].Without a statistically robust estimate for MMR in the baseline year, or in later years, nobody knows whether worldwide MMR has increased or decreased since 1990, other than in a “handful of countries” [26]. The limitations of current estimation techniques are so profound that UNICEF and WHO scientists warn that “it would be inappropriate to compare the 2000 estimates with those for 1990…and draw conclusions about trends” [28].Thus, 11 years after the Cairo Conference first set an explicit target to reduce MMR by 75%, the UN neither has achieved measurement of MMR, nor has it heeded the warnings of its own scientists that MMR is basically immeasurable. The MDG carries that mistaken goal forward to 2015, and the impossibility of measuring and demonstrating success is certainly preordained.MDG 6, Target 8, pledges to “have halted by 2015 and begun to reverse the incidence of…major diseases”, which the UN has interpreted to include TB .Fortunately, the MDG indicators provide for some simpler alternatives: TB disease prevalence and deaths (Indicator 23), and the proportion of TB disease cases detected and cured using a WHO-recommended treatment called “directly observed therapy—short course” . The TB prevalence and case detection indicators are directly measurable, but, ironically, the WHO does not actually measure them. Instead, it uses a unique, arguably outdated estimation method.Nobody can say with scientific confidence what the actual trends for TB are.In the WHO's method, the only true measurement is the number of new, sputum-positive TB cases that are detected and notified to the authorities for treatment with DOTS. To estimate the case detection rate, the WHO divides that number of notified TB cases (the numerator) by an estimate of at-large case incidence (the denominator) [32]. Further, the WHO obtains case incidence from “an independent estimate of the case detection rate” [33]. In effect, the WHO's two estimates are circular and lack definite meaning, for each estimate draws upon the other estimate. Further, the WHO bases this estimation process on inputs that are not always rigorous, and the inputted data are often obtained from collective opinion rather than measurement [33].Accordingly, it is impossible to state the actual trends in TB disease with any degree of statistical confidence. The WHO's best guess is that its estimates “typically range from −20% to [+]40%” in accuracy [32].Others have criticised the circular estimation technique. The WHO's former director for evidence argues that “essentially no empirical basis exists to assess the trend in case detection in regions where tuberculosis is most prevalent, including sub-Saharan Africa” [34]. He calls the WHO's trend estimates “serial guessing” [34]. Certainly, the WHO's leading assumption (known as the “Styblo rule” [35]) has infrequently been tested in Africa, where TB is accelerated by an unparalleled HIV/AIDS epidemic. The WHO's own scientists concede that it may no longer apply there [32].Nevertheless, the WHO maintains that where access to DOTS treatment is extensive—that is, not in Africa—its estimated case detection rates are an adequate guide to true TB trends. This is debatable: in China, which is the WHO's finest DOTS success, actual measurements (not estimations) of TB prevalence corroborated the WHO's case detections less well than expected [36].The best solution now proposed in the scientific literature would redefine the case detection rate, based on measuring true TB prevalence by widespread radiographic or microscopic surveys [31]. Although similar prevalence measurements have been the cornerstone of East Asia's successful attack on TB, the WHO resists changing from estimation to true measurement [37]. As a result, nobody can say with scientific confidence what the actual trends for TB are or whether the TB MDG is on track.The above case studies could leave the dismal impression that all time-limited development goals are immeasurable, lack baseline data, and imply trends having no scientific meaning. Not quite. There is a happy exception: MDG 4, Target 5, which reads to “reduce by two thirds, between 1990 and 2015, the under-five [child] mortality rate” . Conversely, in Zimbabwe during 1988–1999, the U5M rate deteriorated 44% [38]. Unlike other MDGs where such changes are, to put it bluntly, only guessed at, these trends in the U5M rate are properly measured and, importantly, are scientifically meaningful, with confidence intervals that reveal the accuracy and quality of the underlying data. Just by keeping the current DHS technique, and interviewing about 7,000 women per country every five years, it is possible to reliably detect either a 15% gain or loss in the U5M rate with scientific confidence.There is an invaluable and gratifying lesson to draw from the U5M case study: if the UN sets an MDG target that is practical to measure (most are not), and the measurement technique for that MDG target is suitable (most are not), and measurements are taken at the baseline year and in subsequent years (they rarely are), it is then possible to measure the state of the world's health reliably and accurately, and with excellent scientific confidence regarding the trend. In short, it becomes possible to know, not just to guess, if the MDGs are on track or not—even in Africa.I did not write this paper to doubt the moral necessity of investing more money and political capital in global development; that is unarguable, and it would be reprehensible to use these arguments to seed those doubts.Instead, I hope to open an important debate, unable to be fully answered by this paper, on a hitherto almost unexplored question: is the world better off with or without the MDGs and similar UN-sponsored, time-limited, quantitative development goals? The answer to that question must be sought without pro-UN or anti-UN ideology, but with awareness that there are two prongs to consider: (i) whether such goals are interpreted so as to advance the dignity and well-being of the large number of people who live in extreme poverty , and (ii) whether such goals advance the reputation of the UN and the global development establishment. I believe the MDGs risk trouble on both fronts.Viewed objectively, it must be agreed that the MDGs palter. The health goals for 2015 sound quantitative, but for most of them, their quantification is irretrievably flawed. The trends that the health goals allude to are either immeasurable or were not measured properly from the 1990 baseline year onward. This is not an extraordinarily controversial conclusion: recall that in each of the cautionary examples discussed—malaria, maternal mortality, and TB—the UN's own current or former staff have said that the trends are immeasurable or lack baseline data.Short of abandoning the MDGs, the better option is to amend the goals, targets, or indicators—all three levels of the hierarchy—to be feasibly measurable.Unfortunately, the UN leadership has, to date, delayed this option. In a September 2004 memo, one year ahead of the Millennium +5 Summit, the UN's Deputy Secretary General instructed the organisation's experts in charge of the MDG statistics with the following:The [Millennium +5 Summit]…should not be distracted by arguments over the measurement of the MDGs—or worse, over different numbers being used by different agencies for the same indicator…. [P]roposals for modifications of definitions or new indicators will only be considered formally after the [Millennium +5 Summit]… as any changes at this stage would only distract from the result that we would like to achieve. The Deputy Secretary General's order interferes with and shows a profound disrespect for the scientific process—a process that fundamentally is not “distracted by arguments” nor disturbed by “different numbers”. On the contrary, intellectual arguments between scientists are essential for devising new methods of measurements for the MDGs, so that they in turn yield more accurate numbers about the extent and causes of extreme poverty.By suppressing proposals to amend the MDGs ahead of the Millennium +5 Summit, the UN leadership discarded the only timely opportunity to win high-level political support for truly measurable, scientifically meaningful goals. While the Deputy Secretary General plans “a process that will consider recommendations regarding refinements” to the MDGs, the process will commence only after this September's summit . As a reSome may disagree with my emphasis on measurement and timelines. One anonymous peer reviewer of this paper wrote that while measuring the MDGs is “of concern for epidemiologists and others”, my interpretation “misses the point” because the purpose of the MDGs is merely to be exhortatory. “The MDGs are not a measuring exercise”, wrote the reviewer, but instead are a “common vision of what matters most for improving the lives of people in poor countries”.This sort of thinking, although widespread among development professionals, is neglectful towards people living in extreme poverty. Neglect occurs when one touts the MDGs for the “common vision” of, say, reducing maternal mortality, while being indolent about measurements to prove mortality is genuinely decreasing. That formulation values consensus about helping pregnant women, ahead of certainty about helping pregnant women—an outcome that, if they knew about it, the women could easily find ideological and dehumanising.Further, the notion that the MDGs are merely exhortatory discriminates against the world's poorest people. Imagine if European or American leaders, taking aim at poverty in their own countries, set quantitative goals to reduce unemployment or teen pregnancy—only to declare the unemployment and teen pregnancy rates were “not a measuring exercise”. Most people would abhor the dishonesty, for obvious reasons.But if it is shameful, as I believe, to interpret the MDGs as merely exhortatory, imparting no standards of performance, the converse error also exists: to interpret the MDGs as all-encompassing and imparting too many standards of performance.The latest fashion, exemplified by the UN Millennium Project, is to treat the MDGs as catch-alls or tautologies for development itself. In a list entitled “Interventions by MDG Target”, the UN Millennium Project recommends to build “roads” or “transport infrastructure” for all of the following MDG targets: primary education, hunger, gender equality, water and sanitation, child mortality, and, of course, malaria, maternal mortality, and TB [39]. Electricity, slum upgrading, and education are similar panaceas.Definitely roads or electricity matter to holistic development, but justifying those under the cover of goals expressly for child mortality or malaria, makes goal-setting seem pointless. Worse, such justification sounds dishonest—a camouflage job. It is no wonder that with the MDGs subordinated into empty vessels for tenuously related interventions—subordinated into, as Professor Jeffrey Sachs says, just “any international goals”—there is resistance to measure the progress of the specific goals, targets, and indicators with rigor and precision .The MDGs could turn from opportunity to liability.I believe that without thoroughgoing action to change the current scenario see , the MDG• Convene an external (non-UN) scientific peer review to examine the goals, targets, and indicators to ascertain whether the desired trend of improvement in each is, with current data, measurable or estimable at scientifically accepted levels of accuracy and statistical significance.• For those goals, targets, or indicators measurable by household surveys, choose only a single survey instrument; determine the minimum sample size needed to detect favourable or adverse trends with statistical significance; conduct the survey at regular intervals; and make all the micro-level data fully public, so independent scientists can replicate the UN's conclusions. Eliminate the many superfluous household surveys now in use.• For those goals, targets, or indicators not measurable by household surveys, institute sample surveys (“mini censuses”) by creating a large number of new demographic surveillance sites in various countries. The Canadian-funded Tanzania Essential Health Interventions Project is a superb example .• For those goals, targets, or indicators that are not measurable by any practical means, first consider to amend them, and if that is not possible, abandon them .• Within 18 months, hold a high-level UN-sponsored event at which governments ratify final actions for all the above. Have those actions be developed by external scientists and given to the Deputy Secretary General directly.More thoughtful and timely action for the sake of these institutions, and, needless to say, the millions of people who shall live—or die—with the success or failure of the MDGs, is only wise.


There is a low incidence of malaria in Iquitos, Peru, suburbs detected by passive case-detection. This low incidence might be attributable to infections clustered in some households/regions and/or undetected asymptomatic infections.Plasmodium falciparum infections in the previous month. Longitudinal ACD and PCD (ACP+PCD) occurred within at-risk zones, where 137 houses (573 persons) were randomly selected as sentinels, each with one month of weekly active sampling. Entomological captures were conducted in the sentinel houses.Passive case-detection (PCD) during the malaria season (February-July) and an active case-detection (ACD) community-wide survey (March) surveyed 1,907 persons. Each month, April-July, 100-metre at-risk zones were defined by location of P. falciparum and 0.22 Plasmodium vivax infections/person/malaria-season. However, the ACD+PCD prevalence was 0.13 and 0.39, respectively. One explanation for this 4.33 and 1.77-fold increase, respectively, was infection clustering within at-risk zones and contiguous households. Clustering makes PCD, generalized to the entire population, artificially low. Another attributable-factor was that only 41% and 24% of the P. falciparum and P. vivax infections were associated with fever and 80% of the asymptomatic infections had low-density or absent parasitaemias the following week. After accounting for asymptomatic infections, a 2.6-fold increase in ACD+PCD versus PCD was attributable to clustered transmission in at-risk zones.The PCD incidence was 0.03 Even in low transmission, there are frequent highly-clustered asymptomatic infections, making PCD an inadequate measure of incidence. These findings support a strategy of concentrating ACD and insecticide campaigns in houses adjacent to houses were malaria was detected one month prior. Plasmodium species parasites are different from what is found in the widely studied African, Asian or Pacific countries. The incidence of malaria in Peru before 1940 is not well-known, but between 1940 and 1960 there were reports of Plasmodium vivax and Plasmodium malariae infections in northern and central Peru. In the 1960's malaria transmission was very low due to an impressive eradication attempt. However, in the 1980's the eradication campaign was abandoned and house spraying programs were increasingly neglected. Plasmodium falciparum was first reported in Peru's Department of Loreto in 1988 [P. vivax and P. falciparum epidemic between 1995 and 1998  calculated the malaria-attributable death rate in 1997 to be only 0.1% [998 calcuP. falciparum and P. vivax malaria infections [P. falciparum infections and P. vivax infections detected were associated with symptoms and the parasite densities were similar to that expected in non-immune individuals [P. falciparum and 30 with P. vivax by microscopy. Of these, only 8 and 19, respectively, reported a fever. The conclusion was that there were many low density malaria infections that were asymptomatic. However, the question remains whether these were early stage infections that would have subsequently produced symptoms and then have been detected at the health post.The frequency of asymptomatic malaria infection is not known in this or most low transmission regions. There has been a longitudinal study in Brazil which demonstrated asymptomatic fections . In Perufections . Roper eividuals . Howeverividuals . They foP. falciparum and P. vivax infections during weekly active surveillance. The results suggest that, even in low transmission, active case detection provides critical insight into P. falciparum and P. vivax transmission and infection and that active case detection can be spatially and temporally targeted for a feasible malaria intervention strategy.Understanding the continued low malaria transmission and the potential for increased transmission in the Amazon Jungle region of Peru is contingent upon determining the prevalence of a capable malaria vector, clustering of infections within certain households and the presence of asymptomatic malaria. This present study, in a suburban community near Iquitos, determined the level of local malaria transmission, the frequency of individuals presenting with symptoms and the dynamics of P. falciparum and P. vivax malaria transmission. The rural communities in San Juan have P. falciparum and P. vivax infections, mostly detected in the rainy season, which lasts from January to July. Typically, MINSA personnel detects, treats and documents malaria cases by passive-case detection. All persons presenting with a fever at the community-based MINSA health posts or a larger health clinic located in the urban region of San Juan are tested for malaria by microscopy. Individuals go to the MINSA health centers as there is no access to private doctors and anti-malaria treatment is given by MINSA at no cost to the patient. The anti-malaria drug supply is tightly controlled and given as observed therapy  each day to those infected.South of Iquitos, the San Juan District, is a focus of P. falciparum malaria infections, the acceptance by the community and the fact that the community is composed of four villages each separated by approximately two kilometres and yet serviced by the same MINSA health post. Zungarococha (population N = 1907) is composed of 4 villages: Zungarococha town (ZG), Puerto Almendra (PA), Ninarumi (NR) and Llanchama (LL)  Figure . The roaAn. darlingi mosquito is highly prevalent in their community and causes malaria transmission. Public health education is conducted both by local MINSA health promoters and radio announcements. Additionally, throughout the daily interactions with the community and village authorities, the MIGIA investigator team discussed how to decrease the possibility of An. darlingi biting. All of the households included in the survey answered a questionnaire which included questions on bed net and insecticide usage. More than 95% of the households reported using bed nets, although none of the households reported using insecticide treated bed nets or repellants in their homes. Approximately twice per year, the MINSA entomologists conduct fumigation campaigns and apply pyrethoid insecticides to all houses [Members of the community have been informed that l houses .An. darlingi mosquito malaria vector in the Peruvian Amazon [An. darlingi lives near and bites within human households (endophagic behavior). An. darlingi also bites near its breeding sites, which are typically shady edges of quiet rivers (riparian habitats) [An. darlingi have an easily distinguishable one white front leg.Entomology capture studies were conducted to determine the transmission potential within the Zungarococha villages. Mosquitoes were captured by mechanical aspiration from 7–12 pm, the known time of peak biting for the anthropophilic n Amazon . An. darabitats) . Each moP. vivax and P. falciparum incidence. The number of malaria cases per given time were divided by the total population  to determine the incidence by passive case detection. The records were matched by name to the individuals observed in active case detection (see below).This study had a full-time clinical team stationed at the Zungarococha Health Post for passive case detection throughout the year. The MINSA records of malaria detection within the Zungarococha Health Post were reviewed and complied in order to calculate the Active case detection was conducted during the months of March and July, 2003 .The active case detection began with a cross-sectional community-wide survey, wherein all family members were invited for malaria parasite testing and a health survey. Between March 31 and April 5, 2003, there were village-wide surveys of Zungarococha. For simplicity within this manuscript, the community survey is stated to have occurred in March, 2003.P. falciparum infection in the previous month, detected through the community survey results, the health post detection, or the prior month's active case detection. An approximate 100 metre radius circle around the index houses (or a median point between index houses when there were two index houses spaced by less than 50 metres) was defined as an at-risk zone for P. falciparum transmission. If at-risk zones overlapped in a given month, houses were assigned to one of the zones. Each month, all houses within each 100 metre at-risk zone were identified by assigning house numbers (addresses) on a map of each village and entered as list of possible sentinel houses. Of all possible sentinel houses , 10 potential sentinel houses from each at-risk zone were randomly selected. In June and July, this selection was done by a random number generator . The enrolment team for this study would be given this list and then would go to these potential sentinel houses one at a time to recruit all household members for one month of weekly active sampling until at least 30 individuals (living in 5–9 houses) were enrolled within each at-risk zone. The index house were included in this longitudinal active case detection, however, the results from active case detection are not included in this analysis due to these houses not being selected at random.From May until July, 2003, longitudinal active case detection included a monthly selection of houses  located within 100 metres of an "index" house. Houses were called "index" houses if they had at least one person detected with a There were 5–6 at-risk zones during each month of active surveillance, with approximately 150 sentinel individuals enrolled each month, April-July, 2003. Each household member was visited 4 times (once per week for one month), unless there was a positive blood slide that resulted in extra visits. The recruitment and retention was high: 82% of the time all permanent members of each sentinel house consented and enrolled and 86% of consenting individuals completed participation in all 4 weekly visits.For each month of active weekly surveillance, due to the relatively small size of each village (less than 600 square-metres) and the location of index cases, approximately the same zones were defined in successive months of active surveillance. Throughout the study, 70–90% of the houses within PA and NR, and 50–70% of the houses within ZG were included within the zones of our active surveillance.At each visit, whether in the health post, the community visits or the weekly home-visits, a detailed epidemiological questionnaire was administered and a physical examination by a physician was conducted. Axillary temperature was measured by a digital thermometre. 0.25–3 ml of blood, by fingerprick or venipuncture, was collected. Individuals diagnosed with malaria had 3–6 ml of blood collected by venipuncture. Thin and thick blood smears and capillary haematocrit tubes were prepared. The remaining blood was stored in tubes with EDTA, separated by centrifugation, and the sera and packed blood cells were frozen within 18 hours. Haematocrit was measured as packed cell volume (PCV) after centrifugation.There were two microscopists in this study, each having more than 15 years experience. Their ability to for accurate reading of blood slides is well known, and they are the designated quality control monitors for all MINSA malaria microscopy in the Department of Loreto. Blood smears were stained with Giemsa using standard procedure. Using 100× magnification to read the thick smear, all malaria species' trophozoites and gametocytes were counted separately. Microscopy fields were read to count at least 500 white blood cells (WBCs) before diagnosing an individual as negative by microscopy. The parasite density for each species (parasites/μl blood) was determined by number of parasite species (trophozoites and gametocytes counted separately) multiplied by 6,000 and then divided by the total number of WBCs counted. Using 6,000 RBCs per one WBC to determine parasite density was established by the MINSA microscopists after years of counting RBCs and WBCs in malaria infected patients from this region and their continued intermittent checks verify that this remains an appropriate average conversion factor.In passive case detection, where individuals presented at the Zungarococha Health Post, treatment was administered immediately upon diagnosis within the Health Post. In active case detection, household visits occurring in the afternoon, the blood slides were transported to the microscopists' laboratory for reading either on the same day or the following morning. Blood slides from individuals reporting febrile illness within the previous 2 days, having a detected fever ≥ 38.3°C, or having a haematocrit PCV <30% were flagged for immediate reading by microscopists. Blood slides from individuals not reporting the symptoms listed above were read within 6 days after the actual visit and collection of the blood slide. All individuals were revisited on "day i+7." If individuals found positive from the earlier blood slide were now symptomatic at this "day i+7" visit, they were given antimalaria drug treatment. If they remained asymptomatic, the blood smear was flagged for immediate reading. These participants were then re-visited in one day ("day i+8") for a confirmation slide and treatment of all individuals with a positive blood slide on "day i" or "day i+7". Even without symptoms, all cases were treated within 7 days of confirmation of malaria parasites. If a positive slide was detected at the last of the 4 weekly visits, then an extra visit, including an extra blood sample, was made. The physician-nurse team was in the vicinity throughout the study to take a blood smear from anyone presenting with malaria symptoms, even if they were not in the regularly scheduled weekly visits. Again, symptomatic individuals had their blood slides read within one day.P. vivax treatment is chloroquine (10 mg/kg for 3 days) with primaquine (0.5 mg/kg for 7 days). P. falciparum treatment is mefloquine (12.5 mg/kg daily for 2 days) with artesunate (4 mg/kg daily for 3 days) in non-pregnant patients older than 1 year of age. In pregnant women and infants, P. vivax is treated with chloroquine (10 mg/kg daily for 2 days and 5 mg/kg on third day) and P. falciparum is treated with clindomyacin (10 mg/kg 2 times daily for 5 days) and quinine (10 mg/kg 3 times daily for 7 days). The treatments are specific to Plasmodium species, as P. falciparum parasites from this region are highly resistant to chloroquine[Plasmodium species parasites to which they are directed. In all cases the treatments are observed, and a fingerprick blood sample is collected at 7 days and then again at 14 days later to confirm treatment success.Whether in active or passive case detection, all treatments were given through the MINSA authorities, following the MINSA National Drug Policy Guidelines. loroquine. The treP. falciparum versus P. vivax infections. Parasite densities were logarithmically transformed (base 10) in order to normalize the densities and calculate the geometric mean and 95% confidence interval (95%CI). A general linear model logistic regression (GLM logistic) was used to test the correlation between probability of febrile illness and parasite density, while controlling for age.Data was entered using a programme in ACCESS developed specifically for this cohort project. The principle investigator developed a program that displays potential matching records by similarity . The principle investigator and data management specialist determined when records from the health post matched individuals in our active follow-up. After the matching, all names and unnecessary information was removed from the analysis data set. Relational database management and statistical analysis was conducted using the Statistical Analysis Software Version 8 . The Fisher's Exact Test (Fisher's exact) was used to compare the expected versus observed frequency of detecting infections in houses and to compare the frequency of febrile illness associated with All protocols were reviewed and approved by the University of Alabama at Birmingham, Universidad Peruana Cayetano Heredia and the Peruvian Ministerio de Salud (MINSA) Institutional Review Boards for the study of human subjects. Written, informed consent was obtained from all participants. In the case of minors less than seven years old, the parents or guardians gave consent. In the case of minors between seven and eighteen, both assent from the minor and consent from the parents or guardians was obtained prior to enrollment.Anopheles darlingi is an anthropophilic mosquito that bites in human houses as well as in the riparian habitats[An. darlingi , giving 160 entomological captures between the months of April and July, 2003. In April, the month with the highest An. darlingi biting rate, the mean household biting rate was 10–24 An. darlingi bites/person/hour in each village. The biting rate rapidly decreased in the months of May-July, 2003, leading to the dry months of August-December (data not shown). This data supports the previous MINSA reports that there is seasonal P. falciparum and Plasmodium vivax transmission by An. darlingi[ habitats between i Figure . These hP. falciparum and 539 P. vivax infections detected by passive case detection between January, 2003 and March, 2004 (one was a mixed-species infection). Only 11 P. falciparum and 121 P. vivax infections were detected during the low transmission months of January, 2003 and August-December, 2003. Considering infections detected February-July, 2003 and estimating by dividing the total infections detected by the total population size (1907), the passive-case detection incidence was 0.03 P. falciparum and 0.22 P. vivax infections/person/malaria season . Of these infections, 45 P. falciparum and 140 P. vivax infections were detected during the one month of weekly active case surveillance of randomly selected sentinel individuals living in at-risk zones.There were 957 participants in the cross-sectional survey in March. Then, based upon the detection of P. falciparum and P. vivax infection)  Table . From thP. falciparum and 0.39 P. vivax infections/person/malaria season (Table The passive and active (active+passive) case detection prevalence was calculated from all individuals who had passive case detection in the health post, the community survey and active-weekly detection for at least one month. The active+passive prevalence was 0.13 P. falciparum and P. vivax active+passive case detection was 4.33-times and 1.77-times higher, respectively, than the prevalence predicted by passive case detection in the health post . Even more striking was the clustering when considering adjacent houses . The 212 P. vivax infections were detected in 173 individuals . Detecting an individual with more than one infection for a given species was not different from the frequency expected based upon the active+passive prevalence  .Of those surveyed over time, 3 individuals had more than one P. falciparum and less than 1.5 P. vivax infections/person/year. For example, of the 573 individuals in our at-risk zone active surveillance, there were 110 who lived in houses where more than one person within the house had a P. falciparum infection during the 2003 malaria season. The prevalence in this subpopulation within the at-risk zones is only 0.26 P. falciparum infections/person/malaria season. Therefore, even in the population at high P. falciparum infection risk, the transmission would be defined as hypoendemic based upon infection prevalence by standards based upon African transmission[The results show low-level local transmission even within at-risk zones, with the same and adjacent houses being at high risk in the following month Figure . Even ifP. vivax and 4 (14%) P. falciparum infections detected within one month of the time of travel. Therefore, this travel to rural regions with assumed higher malaria transmission (MINSA reports) did have a higher frequency of malaria infection. However, the other 58 P. falciparum and 205 P. vivax infections detected in active case detection were in 544 individuals not reporting travel to more rural regions. Therefore, the majority of infections detected in Zungarococha  could not be explained by travel away from their villages.Participants were asked if they traveled away from their village for their occupations or other reasons during the hours of 6 pm-12 pm. Twenty-nine participants reported travel to a rural location or travel to any location by river within one month of active case detection. Of these 29 travelers, there were 7 (24%) P. falciparum and 212 P. vivax infections were detected. The geometric mean parasite density, considering the first positive blood smear obtained in active surveillance, was 1282 P. falciparum parasites/μl blood (95%CI: 1201–1369) and 321 P. vivax parasites/μl blood (95%CI: 312–331). Of particular interest regarding the transmission potential, 53% of the P. falciparum and 22% of the P. vivax infections had gametocytes detected. The geometric mean gametocyte density was 151 P. falciparum gametocytes/μl blood (95%CI: 134–171) and 120 P. vivax gametocytes/μl blood. The higher gametocytemia frequency of P. falciparum relative to P. vivax is attributable to the difficulty in distinguishing P. vivax gametocytes from trophozoites by microscopy.In the active case detection (community survey and weekly surveillance), 62 P. falciparum cases and 14% for P. vivax cases, respectively (Fisher's exact: p = 0.2329). The symptoms reported in individuals with P. falciparum or P. vivax infections at any time within one month were considered. Of the 62 individuals with P. falciparum infections detected in active case detection, 41%, 3%, 6%, 6%, 5% and 6% reported fever, chills, headache, diarrhea, nausea/vomiting or body aches, respectively. Of the 212 individuals with discrete P. vivax infections detected in active case detection, 24%, 1%, 4%, 9%, 5% and 10% reported fever, chills, headache, diarrhea, nausea/vomiting or body aches, respectively. The proportion of individuals with a detected or reported fever (febrile illness) was significantly higher in P. falciparum versus P. vivax infections (Fisher's exact: p = 0.0096). There were no signs of severe malaria infections  during active surveillance. One P. vivax infection was associated with jaundice.A classic indicator of clinical malaria is the presence of a fever at the time parasites are detected. The frequency of a measured fever in individuals with parasites in blood smears was 21% for P. falciparum infections in the group with febrile illness was 4011/μl (95%CI: 811–9746). In individuals with no reported or detected fever at anytime within one month of the detected P. falciparum parasitaemia, the geometric mean parasite density was 973/μl (95%CI: 142–2078). The parasite density of P. vivax infections in the group with febrile illness was 636/μl (95%CI: 81–2477) versus 391/μl (95%CI: 173–1211) in the group without febrile illness. For P. falciparum, there was a positive correlation between probability of febrile illness and P. falciparum parasite density and (GLM logistic: p = 0.0203), independent of the negative correlation between probability of febrile illness and age (GLM logistic: p = 0.0471). P. vivax parasite density was not significantly correlated with probability of febrile illness and (GLM logistic: p = 0.0833).The geometric mean parasite density of P. falciparum infections, 30 individuals were asymptomatic with no indication of parasites at the time of sampling. However, upon reading their blood smears by microscopy, parasites were detected. The initial day of parasitaemia detection was termed "day i." The follow-up visit of these "day i" positive but asymptomatic individuals was termed "day i+7." At this regularly scheduled visit of these 30 individuals, the regular blood smear was collected and read by microscopy on the same day. However, sixteen individuals did not have parasitaemia upon the "day i+7" visit and remained asymptomatic. Six of the sixteen individuals were treated, even though they were negative by microscopy at the time of treatment, "day i+7". Ten of the sixteen individuals with earlier transient parasitaemias were not given treatment, opting for continued surveillance on the following day ("day i+8"). All ten of these asymptomatic individuals with transient parasitaemias on "day i", but negative on "day i+7" remained asymptomatic and were again negative "day i+8", and despite continued surveillance throughout the study remained without parasitaemia.For asymptomatic individuals, enrolled in weekly surveillance, blood smear microscopy results were not available and reported to the participant until the next scheduled visit, seven days later. This protocol was necessary to prioritize microscopy reading on symptomatic participants and to maintain a logical schedule of participant follow-up visits. Of the 45 individuals in the weekly follow-up visits who had In the 14 cases where asymptomatic parasitaemias were not self-limited to being undetectable by microscopy, the parasite densities were often decreased in the "day i+7" blood sample taken just before treatment. From the 30 asymptomatic individuals, the geometric mean parasite density in the "day i" visits was 1047 parasites/μl blood (95%CI: 951–1153). Considering the 14 individuals with parasitaemia on "day i+7" the geometric mean parasite density was 905 parasites/μl blood (95%CI: 758–1082). The parasite density was higher in the "day i+7" versus the "day i" blood smear in only 9 of the 30 (20%) of the asymptomatic individuals. Therefore, it appeared that the majority of asymptomatic individuals were self-limiting their infections and would not have been detected with malaria if it were not for active case detection.Plasmodium falciparum and Plasmodium vivax malaria have been continuing in low transmission, as detected by passive case detection, since the 1995–1998 epidemic. This study determined the presence of a competent malaria vector, the local spatial and temporal clustering of infections and the prevalence of both symptomatic and asymptomatic parasitaemia in a suburban community.Anopheles darlingi was observed in each village of Zungarococha. Local transmission was demonstrated by finding that over 90% of the infections were in individuals not reporting travel outside of the village. The An. darlingi biting rate, especially in April, 2003, was high . Anopheles darlingi is the most competent malaria vector in South America. However, An. darlingi appears to be a less competent vector for malaria transmission than the Anopheles species prevalent in Africa[P. falciparum prevalence is higher, generally report that 1–20% of the important vector species are infected with P. falciparum sporozoites[An. darlingi biting rate and the high proportion of human infections with gametocytes  suggests ample potential for malaria transmission within each village.The potential for local transmission by in Africa. MalariaP. falciparum transmission, based upon the detection of a P. falciparum infection within the preceding 30 days. The Health Post passive detection showed a population incidence of 0.03 P. falciparum and 0.22 P. vivax infections/person/malaria season. In individuals living in at-risk zones, participating in the cross-sectional survey and participating in weekly visits for one month as randomly selected as sentinels, the active+passive case detection prevalence was 0.13 P. falciparum and 0.39 P. vivax infections/person/malaria season. Therefore, the P. falciparum prevalence detected by active+passive case detection in at-risk zones was 4.77-fold higher than the passive case detection.The infection incidence by passive case detection in the Zungarococha Health Post was compared to the infection prevalence by active and passive case detection (active+passive) in 100-metre zones defined as at-risk to local P. falciparum infections within at-risk zones versus the overall population prevalence is the clustering of infections within at-risk zones in Zungrococha. Passive case detection summarizes the infection incidence by considering the number of infections per the population size of the community. However, because infections were clustered in certain regions of the community, using the whole population as the denominator underestimated the prevalence. A household clustering of malaria infections was detected in a study by Brooker et al[P. falciparum infections[An. darlingi has the potential to fly one kilometre or more to find a blood meal, An. darlingi and other Anopheles species frequently remain in highly restricted localities where hosts are readily available[An. darlingi return for multiple feedings in the same or adjacent houses. Future genetic typing of the malaria parasites both in the human host and mosquito vector will compare the genetic relatedness of the spatially (adjacent houses) and temporally (within one month) clustered infections versus the infections detected in other regions within the villages.One attributable-factor for the 4.77-fold increase in detecting ker et al. Brookernfections. In our available,26. The P. falciparum or P. vivax infections were relatively mild. There was a correlation between febrile illness and P. falciparum parasite density, which was independent of the correlation between febrile illness and age, as has been detected in other studies[P. falciparum or P. vivax infection, respectively. This frequency of febrile illness is lower than that reported by a cross-sectional study in this region conducted by Roshanravan et al, in 1999, only one year after the epidemic's onset[P. falciparum infections, 53% (16/30) had no detectable parasitaemia when they were re-visited or on successive checks for parasitaemia during the following 7 days. Moreover, 10 of the 16 individuals had continued surveillance by at least one additional blood sample 14 days later and continued surveillance by passive case detection throughout the malaria season. Thus, all available evidence suggested that these infections were self-limited.Another attributable-factor for the increased rate of detecting malaria infections within at-risk zones, as compared to the detection in the overall population, is the detection of asymptomatic infections. This study used a broad definition of symptoms: including any fever (reported or observed) or anemia (haematocrit <20% PCV) during the entire month of active follow-up. The symptoms reported from individuals detected with r studies. HoweverP. falciparum infections in Papua New Guinea, Senegal and Tanzania showed that P. falciparum parasites remained detectable by microscopy in almost all blood samples [Having infection follow-up more frequently than 3 times in one week (as in this study) has occurred in a few studies of individuals who had many prior malaria infections. Daily sampling for over two weeks on semi-immune individuals with asymptomatic  samples -15. As i samples -15, the P. falciparum protective immunity requires years of frequent P. falciparum infections to develop [Considering the frequency of asymptomatic infections, with symptoms observed for one month, the results of this study suggest that approximately 40% of infections detected by active case detection would not have been detected by passive case detection in the Health Post. Asymptomatic malaria infections have also been detected in a longitudinal study in Brazil, where transmission was higher than this Peruvian cohort but still considered low transmission . Of part develop -17, the a priori-defined monthly control group in non-at-risk zones is that the incidence of asymptomatic malaria infections within these non-at-risk zones could not be calculated. Now that the possibility of asymptomatic infections in this community is known, a future study will include such control groups for conducting cost-benefit analysis.This study compared the malaria incidence by passive case detection for the total community with the prevalence rates in the 100-metre at risk zones for malaria. The limitation of not having an P. falciparum infections would have gone undetected in the health post, then there is an approximately a 2.6-fold increase (4.33*0.60 = 2.6) in the P. falciparum active+passive prevalence versus the passive population incidence attributable to clustering of infections within at-risk zones. Second, the spatial and temporal clustering of infections was apparent within at-risk zones, with adjacent houses being at highest risk within at-risk zones. By focusing resources for active case detection in the at-risk zones, more than three times the malaria infections were detected and treated versus passive case detection. Future studies will determine the range of focused active case detection and fumigation campaigns to obtain the most cost-effective method for immediate public health and long-term decreases in malaria transmission.The results of this present study, however, are not significantly limited by lacking precise knowledge of asymptomatic infections in non-at-risk zones. First, the attributable-fraction of the increased prevalence in at-risk zones can be estimated by assuming that the frequency of asymptomatic infections in at-risk zones was similar to that in non-at-risk zones. Supposing that, without active case detection, 40% of the The occurrence of clustered infections in at-risk zones and asymptomatic infections contributed to the higher prevalence by active case detection within at-risk zones versus passive case detection generalized to the community population. Currently, passive case detection and treatment is the primary approach to malaria control in Peru. This control method is consistent with PAHO's program guidelines, which do not advocate active case detection. However, according to this longitudinal study in a low transmission community, this control strategy only targets approximately one-third of the malaria infections. Therefore, in regions where active case detection cannot be sustained throughout a community, feasible alternatives to detect and limit malaria transmission are greatly needed.Carter et al. discussed the importance of concentrating often limited and expensive resources and manpower where they would be most effective . Studyinafter detecting a malaria infection in a house in a given month by passive case detection, in the following month actively survey for malaria infections in this and adjacent houses and focus insecticide spraying in these at-risk houses.It is evident that passive case detection, even in low transmission, does not identify the regions most at risk for infection and has the potential of leaving many asymptomatic malaria cases undetected. However, community-wide active case detection in regions of low transmission is highly cost prohibitive for local governments. Additionally, by focusing in regions more at risk to transmission, community participation in active case detection is more easily sustained. The results of the present study suggest a specific public health strategy where resources for active case detection are limited: species and conducted the entomology analysis. EG coordinated the collaboration between UAB, the Peruvian University, UPCH-IMTavH, and MINSA. All authors have read and approved of the content of this manuscript.OHB designed the project, supervised the field team and directed the research team. OHB performed the data management, analysis and writing of the manuscript. WMC coordinated collaboration with MINSA and provided critical background statistics on malaria in Iquitos, such as Figure


Epidemiological studies of malaria in adults who live in malaria endemic areas are scarce. More attention to the natural history of malaria affecting adults is needed to understand the dynamics of malaria infection and its interaction with the immune system. The present study was undertaken to investigate the clinical, parasitological and haematological status of adults exposed to malaria, and to characterize parasites in these individuals who progressively acquire protective immunity.Plasmodium falciparum merozoite surface protein 2 (msp2).A cross-sectional survey of 249 adults was conducted in a malaria endemic area of Mozambique. Clinical, parasitological and haematological status of the study population was recorded. Sub-microscopic infections and multiplicity of infections were investigated using polymerase chain reaction (PCR) and restriction fragment length polymorphism of P. falciparum infection by microscopy (14%) and PCR (42%) decreased progressively during adulthood, in parallel with an increase in the prevalence of sub-microscopic infections. Anaemia was only related to parasitaemia as detected by PCR. Multiplicity of infection decreased with age and was higher in subjects with high P. falciparum densities, highlighting density-dependent constraints upon the PCR technique.Prevalence of P. falciparum malaria. The method of parasite detection has a significant effect on the observed natural history of malaria infections. A more sensitive definition of malaria in adults should be formulated, considering symptoms such as diarrhoea, shivering and headache, combined with the presence of parasitaemia.Adults of Manhiça progressively develop non-sterile, protective immunity against  The epidemiology of malaria in adults who live in malaria endemic areas is a neglected area of research. Malaria control strategies have focussed on children under the age of 5 years and pregnant women, as the majority of malaria-related sickness and death is seen in these two groups . HoweverThe risk of malaria attacks in residents of malaria endemic areas falls as they become older , suggestPlasmodium falciparum infections and substantially reduces parasite loads, but does not prevent infection [The immune mechanisms that deal with a malarial infection probably change with age, as suggested by the age-dependency of malariometric indices , the pyrnfection . The conStudies of malaria in semi-immune adults of Africa are scarce ,15-19. MAnopheles funestus is the main vector and most infections are caused by P. falciparum.The study took place at the Manhiça Health Research Center, in Manhiça (Maputo Province), a rural area in Southern Mozambique. The area, described in detail elsewhere , is coveth July to the 4th August 1999. Pregnant women and individuals who had taken anti-malarial treatment in the week preceding sampling were excluded. After written and witnessed informed consent had been obtained, capillary blood samples were collected by finger prick for preparation of thick and thin blood films, haematocrit and filter paper blot samples . Axillary temperature and details of symptoms potentially due to malaria  were recorded. Results of blood film examination and the haematocrit were sent to participants within two days of sampling, and medical advice and treatment were given when necessary.A sample of 500 adults aged ≥ 15 years was selected randomly from the 1999 demographic census. Potential participants were invited to attend selected sites on a given date during the period 26msp2 and restriction-fragment length polymorphism (RFLP). A piece corresponding to approximately 1/8th of the blot on the filter paper was used for a nested PCR amplification of msp2 and genotyping by restriction with enzymes as described elsewhere [P. falciparum clone 3D7 DNA (50 ng) had been added were included in each set of amplification reactions.Blood slides were processed and read according to quality-controlled procedures as described elsewhere . Haematolsewhere . A negatP. falciparum parasites. Anaemia was defined as a haematocrit <33%. The summary measures consisted of percentage for categorical variables and means for continuous variables. Parasite densities are reported as the geometric mean of parasite-positive samples. The prevalence of sub-microscopic infections was calculated as the number of the PCR-positive samples which had been negative by microscopic examination divided by the total number of PCR-positive samples. Multiplicity of infection (MOI) was defined as the number of distinct msp2-genotypes detected in infected samples. Student's t-test and linear regression were used to assess differences between quantitative variables. The age trends of the different categorical variables were assessed using the Chi-square test for linear trend. The association between parasite density and MOI was calculated separately for each age group by multiple regression analysis. Categorical variables such as sex, positivity by PCR and microscopy, anaemia and presence or absence of symptoms were analysed using Chi-square and logistic regression. A p-value of 0.05 was considered statistically significant. Sensitivity and specificity of the malaria case definition was evaluated using the attributable fraction of fever due to malaria as described elsewhere [Data were double entered using Visual Fox Pro 5.0 and statistical analyses were performed using Stata5. Fever was defined as an observed axillary temperature ≥37.5°C and/or patient-reported fever within the previous 24 h. Clinical malaria was defined as fever with a positive blood slide for asexual This study fell within the national clearance granted in 1996 to the malaria epidemiology studies of the Manhiça Health Research Center by the Ministry of Health/National Institute of Health of Mozambique.Among the 500 names selected from the census, 137 were not traceable. Eleven of the remainder had taken antimalarials, 12 were pregnant and 91 were absent on the day of the survey. Thus, the study included 249 adults whose mean age was 37 years (range 15 to 83 years). In concordance with the overall sex distribution of the adult population in the area, two thirds of the subjects were female.P. falciparum. Only one subject had gametocytes. Prevalence of parasitaemia by microscopy decreased significantly with increasing age (p < 0.001) . All infections were due to P. falciparum infection determined by PCR was 42%, and significantly decreased with age (p < 0.001)   consisted of a single /81 consiThe mean axillary temperature was 36.1°C (range 35.1°C to 37.3°C). None of the adults had fever at the moment of the examination. No significant associations were found between mean temperatures and the prevalence of any symptom, but a significant inverse relationship was found between age and temperature. Doubling age decreased temperature by 0.05°C (p = 0.004). Prevalences of symptoms are shown in Table Anaemia (haematocrit < 33%) was found in 9.8% (24/245) of the subjects (in 4 the haematocrit could not be measured). Twenty-two of the 24 anaemic subjects were females. Haematocrit values were not related to age (p = 0.5). After adjusting for sex, PCR positive subjects had a haematocrit 2.0% lower than the PCR negative subjects (p = 0.002).Clinical malaria, as defined above, was found in 2.4% of the subjects (6/249). The estimated attributable fraction of fever due to malaria was 6.7%. The specificity of our definition was estimated as 91% (95% CI 81% to 98%). Among parasitaemic adults, there was a significant association between high parasite densities and the presence of diarrhoea (p = 0.004) or headache (p = 0.014), and an inverse association between shivers and parasite density (p = 0.029). No relationship was found between MOI and any symptom.P. falciparum prevalence as determined by microscopy (14%) and PCR (42%). Estimates of infection determined by microscopy are probably unreliable in adults because of the high prevalence of P. falciparum infections with densities below the detection threshold of blood film examination. Even prevalence of PCR detected parasites and MOI may be underestimated when parasites reach such low levels that densities fluctuate around the threshold limit of the PCR [P. falciparum clones are differentiated more efficiently in high-density infections.This study, one of the few focussing on malaria in adults from a malaria hyperendemic area ,12,15-19 the PCR . This inThe abundance of sub-microscopic infections in adults from Manhiça and the low specificity of signs and symptoms hamper the definition of a malaria episode. Fever was not detected at the time of examination in any of the adults in this study. Other symptoms such as diarrhoea, shivering and headache, combined with the presence of parasitaemia, could be used to formulate a more sensitive definition of malaria in adults. Special emphasis should be paid to anaemia. In our study area, the significantly higher frequency of anaemia cases among PCR positive individuals might have been due to a reduction in haematocrit because of recent high density infections that have been controlled at the moment of the examination by an efficient immunity or prior treatment. Alternatively, it may have been the result of persistent asymptomatic infections that significantly increase the risk of becoming anaemic.P. falciparum, as detected by PCR. Parasite rate might be even higher during the wet season. Studies in other settings have found similar high prevalences [During the dry season, almost half of the adults from Manhiça were infected by valences , showingvalences . This prTwo forms of antimalarial immunity are believed to occur, an anti-disease and an anti-parasite immunity . The firP. falciparum parasites to low densities with a sub-clinical course, but is not sterilizing. A more sensitive definition of malaria in adults should be formulated, considering other symptoms such as diarrhoea, shivering and headache, combined with the presence of parasitaemia.This study has evidenced the abundance of sub-microscopic infections in adults from Manhiça. Estimates of infection determined by microscopy are probably unreliable, suggesting that the method of parasite detection may have a significant effect on the observed natural history of malaria infections in adults. The increment with age in the prevalence of sub-microscopic infections, together with the trend towards a reduction of parasite densities, suggests that immunity in adults develops during the whole life. This immunity is able to restrict AM carried out the molecular genotyping study, the analysis and interpretation of data and prepared the manuscript. JA carried the statistical analysis and helped to draft the manuscript. CF carried out the sample collection and contributed to the analysis and interpretation of data. FS, BG and MD contributed to the interpretation of the data and drafting of the paper. CM and PA conceived and coordinated the study, participated in the analysis and interpretation of the data, and contributed to the preparation of the manuscript. All authors read and approved the final manuscript.


Obtaining a correct working length is critical to the success of endodontic therapy. Different methods have been used to identify this crucial measurement. The Aim of this clinical study was to compare the effect of working length determination using apex locator alone or in combination with working length radiograph on the apical extent of root canal filling.A total number of 66 patients, 151 canals were randomized into two groups, In group (I) working length was determined by apex locator alone, while in group (II) working length was determined by apex locator confirmed by working length radiograph, length of obturation was assessed, and the total number of radiographs was recorded. The data were analyzed using SAS system and T. tests were carried out. Statistical significance was considered to be P ≤ 0.05.Sixty seven canals in group I were treated with a mean distance from the tip of root canal filling to radiographic apex -0.5 mm ± 0.5 and a mean of a total number of radiographs of 2.0, while in group II eighty four canals were treated with a mean distance from the tip of root canal filling to radiographic apex -0.4 mm ± 0.5 and a mean of a total number of radiographs of 3.2. There was no statistically significant difference in the mean distance from the tip of root filling to radiographic apex between group I and group II (P > 0.05).The practice of using electronic apex locator in the determination of working length is useful and reliable with no statistical difference of the radiographic extent of root canal filling when using apex locator alone or in combination with working length radiograph. Under the clinical conditions of this study, it is suggested that the correct use of an apex locator alone could prevent the need for further diagnostic radiographs for determination of working length. This method can be useful in patients who need not to be exposed to repeated radiation because of mental, medical or oral conditions. One of the main concerns in root canal treatment is to determine how far working instruments should be advanced within the root canal, and at what point the preparation and obturation should be located ,2.The significance of the apical constriction in the root canal treatment is well recognized. It is generally accepted that the preparation and obturation should be at or short of the apical constriction .Although radiography is the most commonly used diagnostic aid in endodontics, It can, at best, give an estimate of this histological structure and although clinically desirable, averages used to define the apical constriction from radiographic apex could lead to over or under filling .In theory apex locator that locates the apical constriction may more accurately determines the physiological end-point of root canal therapy. The main shortcoming of early apex locators (erroneous reading with electrolytes)  was overIt is believed that apex locators should not be considered as a replacement of radiographs  but can Although, accurate measurements were achieved using modern apex locators ,16-21, tThe purpose of this clinical study was to compare the effect of working length determination using apex locator alone or in combination with working length radiograph on the apical extent of root canal filling.A total number of 66 patients with 151 canals were treated at endodontic department, Jordan University Hospital. Informed written consent was obtained from each patient following ethical committee approval from the deanship of academic research at the University of Jordan.The patients were 30 males and 36 females between 12–65 years old with a mean of (35.3 ± 15.5). Patients that used heart pacemakers were excluded. All patients were referred for endodontic treatment and were treated by the author. A data sheets were used for recording the patient's profile, chief complaint, history of present illness, medical history, dental history, investigations, diagnosis and treatment planning, vitality of the tooth on access as determined by bleeding, working length measurements, procedures done, total number of radiographs, number of radiographic retakes, total number of visits, the incidence of flare-ups (that require unscheduled endodontic intervention), with all of the corresponding radiographs .® Daron Pakhsh, Iran) pulp cavity was accessed using a straight fissure diamond bur in a high speed contrangle hand piece under abundant water spray followed by small round bur in a slow speed hand piece, after initial access the tooth was isolated using rubber dam. The walls of the access cavity were adjusted using endo Z bur , the entrances of the root canals were irrigated with 2.5 % sodium hypochlorite solution and dried by aspiration, no attempt was made to clean debris or pulp tissue remnants prior to introducing a size 10 k-file  into the canals. The Tri Auto ZX® was used on EMR Mode- Electronic measurement of a root canal based on manufacturer's recommendations (group I). The lip-clip (contrary electrode) was placed in the corner of the patient's mouth and the file holder was attached onto the shaft of the hand file. The size 10 K-file was advanced apically into the canal until the beeping sound and the light emitting diode (LED) marked APEX on the panel began to glow, indicating that the tip of the file had reached the anatomical end of the canal in the periodontium. The file was withdrawn with a slow counterclockwise turn until the red LED APEX light went out, suggesting that the tip of the file was at the predetermined length of the apical constriction. At that time, the 0.5 mm green LED light illuminated and a rapid tone was heard. The distance from the file tip to the silicone stop was then measured to an accuracy of 0.5 mm  and registered as working length. In group (II) with a size 10 or 15 K-files set on a pre-estimated electronic length inside root canals a working length radiograph  placed in a film holder (Hawe Endo-bite (anterior/posterior), Kerr Hawe SA, Switzerland) was taken . The radiographic length was then recorded. If any discrepancy between the electronic length and the radiographic length was found then a decision was made on the appropriate adjustment based on both the radiographic picture aided by the electronic measurements. Radiographs were repeated if root apices were not clear.A preoperative periapical radiograph  placed in a film holder  was taken . After administration of local anesthesia  in a step back technique, followed by nickel titanium protaper rotary files  in Tri Auto ZX hand piece pre set on the manual mode, accompanied by copious irrigation of sodium hypochlorite 2.5%, before obturation the canal was thoroughly dried, AH26 was the sealer used with hot lateral condensation of conventional gutta percha  using hand spreader  heated in a bead sterilizer. A postoperative periapical radiograph  placed in a film holder  was taken . Root canal treatment was finished in one to three visits according to pathological status, time available, the difficulty of the case and patient cooperation.Periapical post-obturation radiographs were examined on x-ray illuminator and by the aid of magnifying loupes 3.5 × . Distances from the end of root canal filling to the radiographic apex were measured in millimeter to an accuracy of 0.5 mm twice at two separate occasions and the means were calculated and recorded.The data were analyzed using SAS system and T. tests were carried out. Statistical significance was considered to be P ≤ 0.05.A total of 67 canals in group I, in which an apex locator was used without a radiograph, showed a mean distance from the tip of root canal filling to radiographic apex of -0.5 mm and a mean of a total number of radiographs of only 2.0 was needed. While in group II, in which an apex locator was used in conjunction to a radiograph, a total of 84 canals showed a mean distance from the tip of root canal filling to radiographic apex -0.4 mm and a mean of a total number of radiographs of only 3.2, including a preoperative and a postoperative radiographs, was needed table . There wWhen root canals were divided into subgroups according to tooth position and pulpal status, similar results were obtained showing no statistical difference in the mean distance from the end of the root filling to radiographic apex between the two groups in all subgroups treated table .The total number of radiographs which was needed during treatment was counted in the different subgroups and a mean of two radiographs and approximately three radiographs 3.1–3.4) was scored in group I and group II, respectively  ,30 partiThe performance of the apex locator showed similar reliability obtained in previousStudies ,17-21 inAccording to Fouad and Reid 2000  a clinicIn agreement with previous studies ,25 the pThe results of the present study also showed that electronic predetermination of working length prior to working length radiograph resulted in a total number of a mean of approximately three radiographs including pre-operative and post-operative radiographs which means that approximately a zero retake was needed. This agrees with previous study which concluded that adjunctive use of an apex locator reduces the number of diagnostic radiographs required for working length determination . AnotherIt must be emphasized that the use of apex locator alone without a preoperative and postoperative radiograph is not a recommended practice due to the large variation in tooth morphology and medico-legal record keeping requirements . A recenThe practice of using electronic apex locator in the determination of working length is useful and reliable with no statistical difference of the radiographic extent of root canal filling when using apex locator alone or in combination with working length radiograph. Under the clinical conditions of this study, it is suggested that the correct use of an apex locator alone could prevent the need for further diagnostic radiographs for determination of working length. This method can be useful in patients who need not to be exposed to repeated radiation because of mental, medical or oral conditions.The author(s) declare that they have no competing interests.The pre-publication history for this paper can be accessed here: