Lymphatic filariasis (LF) and soil-transmitted helminths (STH) have been targeted since 2000 in Haiti, with a strong mass drug administration (MDA) program led by the Ministry of Public Health and Population and its collaborating international partners. By 2012, Haiti’s neglected tropical disease (NTD) program had reached full national scale, and with such consistently good epidemiological coverage that it is now able to stop treatment for LF throughout almost all of the country. Essential to this success have been in the detail of how MDAs were implemented. These key programmatic elements included ensuring strong community awareness through an evidence-based, multi-channel communication and education campaign facilitated by voluntary drug distributors; strengthening community trust of the drug distributors by ensuring that respected community members were recruited and received appropriate training, supervision, identification, and motivation; enforcing a “directly observed treatment” strategy; providing easy access to treatment though numerous distribution posts and a strong drug supply chain; and ensuring quality data collection that was used to guide and inform MDA strategies. The evidence that these strategies were effective lies in both the high treatment coverage obtained– 100% geographical coverage reached in 2012, with almost all districts consistently achieving well above the epidemiological coverage targets of 65% for LF and 75% for STH—and the significant reduction in burden of infection– 45 communes having reached the target threshold for stopping treatment for LF. By taking advantage of sustained international financial and technical support, especially during the past eight years, Haiti’s very successful MDA campaign resulted in steady progress toward LF elimination and development of a strong foundation for ongoing STH control. These efforts, as described, have not only helped establish the global portfolio of “best practices” for NTD control but also are poised to help solve two of the most important future NTD challenges—how to maintain control of STH infections after the community-based LF “treatment platform” ceases and how to ensure appropriate morbidity management for patients currently suffering from lymphatic filarial disease.
Neglected tropical diseases (NTDs) are a group of 17 parasitic, bacterial, and viral infections affecting more than 1 billion people globally [1]. Seven of these are known as the preventative chemotherapy NTDs because they can be eliminated or controlled by administering medicines to entire eligible populations or large segments of these populations in an effort to reduce transmission of infection and prevent disease. Four preventative chemotherapy NTDs are endemic in Haiti—lymphatic filariasis (LF) and the three soil-transmitted helminth (STH) infections caused by Ascaris, Trichuris, and hookworm. LF is one of the world’s most debilitating parasitic diseases, causing lymphedema, elephantiasis, hydrocele (enlarged scrotum by fluid accumulation), and hidden internal damage to the lymphatic and renal systems of affected individuals [2]. Furthermore, as a disease associated with stigma, despair, hopelessness, embarrassment, ridicule, frustration, and economic burden [3], LF can also cause significant mental health complications that reach far beyond even its physical morbidity [4]. STH causes a wide range of intestinal symptoms and has also been associated with poor cognitive development and learning capacities in children [2]. Furthermore, STH can cause anemia in women of child-bearing age, which is both detrimental to the mother’s health during pregnancy and can lead to low birth weight [5]. Haiti is one of only four countries in the Americas where LF transmission still occurs, and it is home to the largest at-risk population in the region [6,7]. In Haiti, LF is caused by Wuchereria bancrofti filarial parasites, primarily transmitted by Culex quinquefasciatus mosquitoes [7,8]. In 2000, a nationwide mapping exercise reported an infection prevalence (assessed by filarial antigen) as high as 45% in children 6 to 11 years old, with infected children identified in 117 of the country’s present 140 communes (133 communes at that time) [9]. Nationwide “mapping” for STH infections was carried out in 2002, with all of Haiti’s ten departments (previously reported as nine due to redistricting) reporting >20% prevalence and two of these with >50% prevalence [10]. Addressing such NTD challenges is complex. Although health experts and international organizations have presented general recommended approaches for integrated programs targeting NTD control or elimination [11], the global portfolio of “best practices” can only grow through the addition of detailed records of individual national experiences. Indeed, the success of national NTD programs (or at a minimum, their avoidance of failure) depends on understanding the methods used to implement and assess programs in those countries where NTD programs are already mature or complete. In this regard, Haiti could make important contributions to the accumulating experiences of implementing integrated NTD programs [12,13]. This current report, while recognizing the importance of the contributions of all of Haiti’s principal NTD stakeholders[14], focuses on the efforts implemented by the Haitian government and a large project (ENVISION) supported by the U. S. Agency for International Development (USAID). ENVISION is led by RTI International and is being implemented in 19 countries globally [http: //www. ntdenvision. org]; in Haiti, IMA World Health leads the ENVISION activities.
Treatment coverage is a measure of whether programs are on track to achieve program goals and control/elimination targets. Good coverage was reported (Table 1) – 100% geographical coverage was achieved in 2012 and national coverage targets were reached for both STH (≥75%) and LF (≥65%) across most communes. In communes supported by ENVISION, the average epidemiological coverage for LF MDA rounds ranged from 86% to 94% (Table 1). The number of communes with coverage below the 65% target ranged from one to five in any given year, with no systematically low-performing communes identified. Post-treatment coverage surveys were used to validate the coverage routinely reported by CDDs. Results of the coverage surveys generally confirmed that coverage rates were at least 65%, and often substantially higher (Table 2). KAP questions were added to the coverage surveys in both 2012 and 2013 (Table 3). Results showed that it was easy for people to reach treatment posts (96% of respondents in 2012 and 82% in 2013 reported that the treatment post was “easily accessible” or “not too far”) and that awareness levels on the program were high (95% of respondents in 2012 and 89% in 2013 reported knowing the MDA was going to occur). While knowledge of signs and symptoms of LF was good (85% of respondents in 2012 and 59% in 2013 correctly reported at least one sign or symptom of LF), knowledge on prevention methods was low (27% of respondents in 2012 and 47% in 2013 correctly reported at least one method to prevent infection). A similar study in Léogâne following a single MDA, conducted by MSPP with support from CDC, had found no significant association between knowledge of disease and treatment [25]. The factor most strongly associated with taking the treatment was access, with adjusted odds ratios of 30 and 56. 2 for 2012 and 2013 respectively, p <0. 001 (t-test). Caution should be exercised when interpreting the odds ratios not to overemphasize the significance of such high odds ratios. If an outcome is rare, odds ratios and relative risk would be roughly equivalent. Here, since the majority of the surveyed took the drug, the odds ratio and relative risk are different. The unadjusted relative risk is 2. Awareness of the program was also significantly associated with taking the drugs (odds ratios of 5. 8 and 12. 1 for 2012 and 2013 respectively, p <0. 001 [t-test]). The association between knowledge of disease and taking treatment was inconclusive—knowledge was not associated with taking the treatment in 2012 but was significantly associated in 2013 –odds ratio of 1. 8 (p = 0. 002) for persons who could reports signs and symptoms and odds ratio of 2. 7 (p <0. 001) for ability to report prevention strategies. Program impact is first measured at sentinel and spot-check sites—these are conducted at midterm after two to three MDA rounds and again before proceeding to conduct the more extensive TAS, following a minimum of five MDA rounds. Once a commune has completed a minimum of five rounds of MDA, with epidemiological coverage >65% and where sentinel site W. bancrofti antigen levels are below 2%, TAS should be implemented to determine whether MDA can be stopped [24]. For these TAS, communes may be grouped into larger evaluation units (EUs) based on similar epidemiologic characteristics. Results are reported for areas supported by ENVISION only, where the program was implemented as described in the methods section. In 2014–2015, sentinel and spot-check surveys were conducted in 23 communes as part of either midterm or pre-TAS surveys (Table 4). In all communes, there was a marked decrease in infection prevalence as compared with initial mapping results. Results were below the threshold of 2% antigenemia in 19 of the 23 sites (Fig 4); 7 of those sites (conducting midterm assessments) had completed only three or four rounds of MDA, and all 7 had already reached the 2% threshold. MDA was continued in these areas based on current global guidelines to conduct a minimum of five rounds. On the other hand, four sites had large reductions but failed to drop below the critical threshold, even after six or seven rounds (Table 4). The principal difference between these two groups is that the 19 sites where infection rates were reported as below the 2% threshold typically had lower prevalence rates at baseline; despite not meeting the criteria to stop MDA, the substantial decrease in prevalence (i. e. , ranging from 28% to 39% at baseline to between 2. 3% and 6. 5% pre-TAS) among those four sites is viewed as a programmatic success (Table 4). By mid-2015, TAS had been implemented in a total of 13 EUs, 10 of which achieved the prevalence threshold required to stop MDA. These 10 EUs are made up of a total of 44 communes in which, according to WHO guidelines, MDA can now be stopped, while post-MDA surveillance will continue for an additional four to six years. In the other three EUs (made up of three communes), MDA will continue for a minimum of two more years. For STH, a national survey was conducted in 2013 to determine the STH infection prevalence in school children (aged from 6 to 16 years old), at least five years after the program of annual MDA with ALB+DEC had begun. This survey showed that STH prevalence had decreased in 9 of 10 departments, with STH prevalence at or below 10% in 3 departments and at or below 20% in another 6 departments. In the tenth department (Grand’Anse), which had an initial prevalence of 72% when surveyed in 2001, the decline was not as pronounced as in the other nine, and the prevalence of infection remained at 55%[26]. Although these results are encouraging and show significant progress in addressing the problems caused by STH in Haiti, they also highlight the question of how progress will continue after support for annual MDA targeting LF ceases. Program costs. Detailed program cost assessments have been carried out for those communes where MSPP activities have been supported by ENVISION. Although relative costs for some of the program activities did vary slightly from year to year, drug delivery costs always predominated, especially when including social mobilization costs (Fig 5). Because ALB is provided by GlaxoSmithKline at no cost to the program, and since the DEC is quite inexpensive, the cost of medicines (i. e. , the sine qua non of MDA strategies) to the national program remains relatively low. Between 2010 and 2013, the per person treated cost of the program—characterized predominantly by MDA—has remained steady (US$0. 35–0. 37). However, in 2014 an increase in total budget was observed as the requirement for more comprehensive M&E efforts, including TAS surveys, became necessary.
The likelihood of taking the offered treatment has been positively associated in a number of studies with the community’s knowledge and understanding of the disease, its transmission, MDA strategy, and possible side effects; the community’s perceived risk of getting the disease; and history of side effects experienced [28–33]. In Haiti, however, knowledge of disease signs and symptoms was generally low and not strongly associated with taking part in MDA. The most important factors in determining whether people took the treatment offered them were (1) knowing that the MDA was to take place and (2) the ease of access to treatment posts. It is also of note that treatment in Haiti’s NTD program is directly observed, a factor associated in other settings with increased likelihood of community participation [29,34–38]. Reluctance to take treatment due to fear of minor side effects was low, reflecting the importance placed on informing the community about expected side effects—achieved through emphasis during CDD training and through dissemination of IEC messages. The program also benefitted from the fact that there were no reported serious adverse events. This program has been able to extensively leverage pre-existing relationships among ENVISION, the field MSPP personnel, and the community leaders—all of whom emphasize the involvement of the community, thereby building on the foundation of existing strong social capital. Other studies also support the idea that drug distributors who are known and respected by the community will have better success in treating the population [34]. The factor most strongly associated with taking the drugs in this program was ready access to treatment (odds ratios of 30 and 56. 2 for 2012 and 2013 respectively, p <0. 001). The program’s attention to logistics—in terms of number and location of posts, as well as assurance that the posts are attended by well-trained and supported CDDs—accompanied by a strong supply chain that ensured the availability of treatments, were critical to the successful achievement of persistent high treatment coverage. In light of the strong evidence presented on good coverage in MDA rounds obtained by the Haitian program, the excellent results of the assessment of impact on infection at sentinel, spot-check, and evaluation sites should not be surprising. LYMFASIM, a mathematical model predicting elimination of LF using an MDA approach, was developed based on a similar scenario in India, where C. quinquefasciatus is the vector and W. bancrofti the parasite, but where ivermectin was used instead of DEC. This model predicted that the number of rounds necessary to achieve elimination depends to a large extent on both coverage and the pre-program endemicity level [39]. This prediction was well corroborated in Haiti’s experience– 19 of the 23 sentinel sites tested in 2014–2015 reached below the critical 2% antigen prevalence threshold. The four sites that did not reach this threshold, despite at least six rounds of MDA with high epidemiological drug coverage (≥83%), had very high baseline antigen prevalence (28%–39%; Fig 4). Earlier studies in Léogâne, Haiti also reported slower declines—from 50% to only 14% following seven rounds of MDA [40]. As noted earlier, seven sentinel sites with initially much lower baseline prevalence had already reached below the <2% antigenemia threshold after only three to four rounds of MDA. These communes continued to implement another one to two rounds of MDA following current WHO guidelines. Researchers in Haiti’s La Tortue Island earlier reported a successful TAS survey and the stopping of MDA after just two rounds of treatment [16]. In the neighboring Dominican Republic, similar results—reduction of antigenemia to below threshold after three rounds of MDA—were found in the urban center of the country, again with low baseline prevalence and high program coverage [41]. There is potential for programmatic efficiencies if programs targeting LF elimination could be successful with fewer rounds of MDA than are now recommended; whether this would be sufficient to interrupt transmission will need to be determined by operational research. In addition to completing efforts to eliminate LF, Haiti’s NTD program needs to sustain achievements of reduced STH burden. During recent years, the STH program has relied on the fact that ALB is administered to the whole population as part of the LF MDA. As the LF program progressively meets the criteria for stopping MDA, another platform will be needed for delivery of STH treatments. Haiti’s plan is to focus on school-based, STH-only MDA and to add water, sanitation, and hygiene activities. In 2015, the InterAmerican Development Bank provided the MSPP with funds for a national deworming campaign. The InterAmerican Development Bank drew upon IMA’s expertise for support in training of drug distributors and working with department-level STH leads to formulate best-practice MDA strategies—illustrating the continued integration and collaboration between the two disease programs and the potential resources that have been developed in country and can be leveraged to ensure the sustainability of STH control activities. As MDA activities are now reaching the stopping point, Haiti has started to turn its attention to morbidity control efforts for LF, building on hydrocele surgery efforts and lymphedema patient support groups that have been implemented in Léogâne [42]. The MSPP updated its national morbidity management and disability prevention (MMDP) strategic plan in early 2016, which includes rolling out the use of WHO’s new MMDP situation analysis tools to estimate the number of patients with hydrocele or lymphedema, identify platforms to support MMDP activities, identify strategies to mobilize patients, and identify the human resources and funding needs. Finally, plans are also in place to work Hispaniola-wide on a malaria elimination plan, harnessing the momentum already gained for LF elimination and further increasing the probability of LF elimination though vector control [43]. In summary, in this mostly rural Haitian setting, a very successful MDA campaign was launched in 2001 with sustained high coverage rates, resulting in steady progress toward LF elimination (with more MDA rounds being needed in areas with high baseline prevalence and fewer where prevalence was initially low). A strong foundation for ongoing STH control has also been established. The strategies utilized with proven success by the program are summarized in Box 1. This list is an important contribution to the development of the global evidence base on MDA best practices.
We present evidence of Haiti’s successful neglected tropical disease (NTD) program targeting lymphatic filariasis and soil-transmitted helminths and the methods used to achieve this success. By 2012, Haiti’s NTD program had reached full national scale, with such consistently good treatment coverage that the program is now able to stop treatment for lymphatic filariasis in much of the country. These findings are in line with the predictions and expectations of the global community for countries where high coverage is achieved for program implementation. In addition to the evidence of successful program outcomes, we present a detailed description of how the program was implemented—from facilitating the effectiveness of the drug distributors to improving drug logistics and supporting a well-informed population. These methods described can be used to inform the design of other mass drug administration programs and enhance the development of global “best practices” guidance.
medicine and health sciences
education
sociology
geographical locations
tropical diseases
social sciences
parasitic diseases
north america
pharmaceutics
neglected tropical diseases
pharmacology
caribbean
schools
adverse reactions
drug distribution
haiti
pharmacokinetics
people and places
helminth infections
drug therapy
soil-transmitted helminthiases
drug information
Controlling Neglected Tropical Diseases (NTDs) in Haiti: Implementation Strategies and Evidence of Their Success