The fight against onchocerciasis in Africa has boomed thanks to the Community Directed Treatment with Ivermectin (CDTI) program. However, in Cameroon, after more than 15 years of mass treatment, onchocerciasis prevalence is still above the non-transmission threshold. This study aimed to explore a possible association between people’s beliefs/perceptions of onchocerciasis and of CDTI program, and their adherence to ivermectin in three regions of Cameroon. A cross sectional survey was carried out in three health districts with persistent high onchocerciasis prevalence. Participants were randomly selected in 30 clusters per district. Adherence to ivermectin was comparable between Bafang and Bafia (55. 0% and 48. 8%, respectively, p>0. 05) and lower in Yabassi (40. 7%). Among all factors related to program perceptions and disease representations that were studied, perceptions of the program are the ones that were most determinant in adherence to ivermectin. People who had a “not positive” opinion of ivermectin distribution campaigns were less compliant than those who had a positive opinion about the campaigns (40% vs 55% in Bafang, and 48% vs 62% in Bafia, p<0. 01), as well as those who had a negative appreciation of community drug distributors’ commitment (22% vs 53% in Bafang, 33% vs 59% in Bafia, 27% vs 47% in Yabassi; p<0. 01). The most common misconception about onchocerciasis transmission was the lack of hygiene, especially in Bafia and Yabassi. In Bafang, high proportions of people believed that onchocerciasis was due to high consumption of sugar (31% vs less than 5% in Bafia and Yabassi, p<0. 001). There are still frequent misconceptions about onchocerciasis transmission in Cameroon. Perceptions of ivermectin distribution campaigns are more strongly associated to adherence. In addition to education/sensitisation on onchocerciasis during the implementation of the CDTI program, local health authorities should strive to better involve communities and more encourage community distributors’ work.
Onchocerciasis, also known as river blindness is a vector-borne parasitic disease caused by a very thin worm, Onchocerca volvulus, and transmitted by the bites of black flies belonging to the Simulium species. The burden of the disease is observed more in Africa, especially among the poorest population of the continent [1]. In fact, onchocerciasis is responsible for debilitating eyes and skin lesions, having negative psychosocial and economic impact at local (communities) and even national levels in the countries affected [2,3]. Since 1995, onchocerciasis control activities focus on the Community Directed Treatment with Ivermectin (CDTI), a strategy adopted in African countries by the African Program for Onchocerciasis Control (APOC) consisting of yearly mass administration of ivermectin. Multiple studies show evidence of remarkable improvement in the ivermectin treatment coverage with the CDTI strategy, thus contributing to successful reductions in onchocerciasis transmission and prevalence [3–6]. However, ivermectin is only effective on Onchocerca microfilariae and has no known lethal effect on adult worms, which reproductive lifespan is estimated to about 14 years [7]. This is one of the main reason why, to achieve the onchocerciasis elimination goal, ivermectin treatment must be repeated annually for at least 15 years without reinfection [3]. Considering this, onchocerciasis corresponds to the “long period of supervision, observation and care” criterion to be classified as a chronic disease, with regards to the definition adopted by WHO in 2003 [8]. As with many chronic diseases, the major issue of onchocerciasis control and elimination is adherence to mass drug administrations (MDA). The WHO adherence project in 2003 defined adherence to be, the “extent to which a person’s behaviour–taking medication, following a diet, and/or executing lifestyle changes, corresponds with agreed recommendations” [8]. One of the critical factors taken in account during the elaboration of the conceptual framework of onchocerciasis elimination process was the treatment coverage [3], which is the percentage of population taking the drug in a given area during a given MDA. However, treatment coverage gives a picture at community level, whereas adherence considers each individual inside the community. In other words good coverage does not necessarily guarantee good adherence (the same individuals take the drug each year), as shown by Brieger et al. , in communities with optimal coverage they found ‘a fairly large pool of people who had taken in less than three times in the 8 years since the programme began’ [9]. Evidence from several studies shows that the individuals who don’t take ivermectin each year may provide sources of reinfection for their communities [9–12]. The challenge of adherence in the specific context of onchocerciasis is enhanced by the fact that in the frame of MDA, all inhabitants in a selected zone, even if those who are apparently in good health, have to take the drug. For instance in a zone of 50% of onchocerciasis prevalence, there are 50% of “healthy” people (but with high risk of developing the disease) who have to comply in a yearly treatment which is accompanied by constraints such as stop alcohol intake the day of treatment, and potential side effects including tiredness with resultant impact in their daily activities, knowing that alcohol consumption and fear of side effects are documented reasons for ivermectin avoidance [13,14]. More generally, the main factors associated with compliance to ivermectin found in the literature include non-modifiable characteristics like age and gender, and also modifiable factors such as perceived susceptibility to onchocerciasis, perception of program organization, social influence and support, and perceived benefits and risks of ivermectin [10,12,15–17]. In addition to those studies, it is really valuable to have further documentation about the importance and the balance of the main factors related to compliance, especially in the frame of the new resolutions for onchocerciasis elimination within the 2016–2025 period which include intensification of MDA and extension of pre-existing CDTI zones [18]. Moreover, it is also important to have further documentation on adherence in the context of a country like Cameroon, where despite 15 years of treatment onchocerciasis prevalence is persistently high in many CDTI zones, remaining above the expected prevalence as predicted in the elimination process [19,20]. The aim of this study was therefore to explore possible associations between people’s perceptions of CDTI program, their beliefs on onchocerciasis, with their adherence to ivermectin in three Cameroonian Health Districts (HDs), located in three different regions of the country where onchocerciasis prevalence is still above the transmission threshold.
We conducted a cross sectional cluster study, with 30 clusters in each health district corresponding to 30 different communities. These communities were randomly selected using a proportional-to-population size method based on sizes from the 2014 CDD census in the targeted HDs. Data collection was done using a pre tested questionnaire administered to participants by trained research assistants. The study was done between April and June 2015 in three HDs implementing the CDTI program in Cameroon: Bafang, Bafia and Yabassi. Located in 3 border regions in the Centre-West area of Cameroon, those HDs have different prevalence of onchocerciasis. They have in common agriculture as main productive activity, and French as predominant official language of communication. Sample size computation in each HD was based on the hypothesis that at least 50% (non-informative prior prevalence) of respondents will have a positive perception on onchocerciasis and CDTI program, using a 10% margin error, a design effect of 4 for correcting for a high intra clusters correlation, and assuming a non-respondent loss rate of 10%. Under such assumptions, the minimal size for each HD was 421 subjects. To obtain those 421 individuals in each HD, we selected 30 clusters, corresponding to 30 different communities. These communities were randomly selected using a proportional-to-population size method based on sizes from the 2014 CDD census in the targeted HDs. Since it is quite difficult to get an accurate list of households, especially in the rural areas of Cameroon, the households in each community were randomly selected by the research assistant who took the direction indicated by the bottle neck after turning a bottle on the ground, from a central point within the community (the health centre of the village or the chief’s house) and taking all households located in his right side until reaching the required number of households (421 households to have 421 respondents). In the event that he found an endpoint, he returned to the main point of the village and repeated the bottle operation. In each household, the respondent was selected among the present eligible members by tossing a coin, after the approval of the head of household. In case the head of household rejected the toss, he/she was given the opportunity to select the respondent of his choice. All individuals found in the households were eligible for the interview except: visitors, people aged less than 15 years and those who couldn’t understand nor answer in French. Data were collected by 10 trained research assistants (RAs), each of them were responsible for the administration of 43 face-to-face interviews per district. The collection instrument consisted of a French-structured questionnaire set up to provide socio-demographic information: age, sex, level of instruction, occupation, marital status, religion, ethnicity, length of stay in the village. The other information of the questionnaire concerned people’s beliefs on onchocerciasis, their perceptions of CDTI program, and information on adherence to ivermectin. Some of these questions included experience/opinion on onchocerciasis transmission, severity and curability; opinion on ivermectin efficacy; appreciation of ivermectin MDA campaigns organization and usefulness; and opinion on CDDs work. Prior to data collection, a pre-test of the questionnaire was done in each HD, in the villages/communities far from those selected for the study. During the pre-test, it was realized that most of the respondents were neither familiar with the name/acronym “onchocerciasis” nor with “CDTI Program”. These name/acronyms were thus replaced respectively by “filaria” and “Mectizan Campaign”. Respondents’ beliefs on onchocerciasis (filaria) were assessed by seeking their opinions on transmission, filaria severity and possible treatment, using multiple choices semi-closed questions. Their perceptions of CDTI Program was obtained by asking semi-closed questions on opinions about ivermectin MDA Campaigns, CDDs commitment and ivermectin efficacy. Adherence to ivermectin was defined by systematic (regular) intake during each campaigns, assessed by asking to the participants if they take ivermectin every year since they started taking it. This question was asked after two previous “put in track” questions concerning ivermectin intake at least once in their life, and ivermectin intake during the last campaign. Data were analysed with the statistical software Stata version 13. Proportions were compared using Chi2 tests in univariate analyses. Variables associated with adherence to treatment in univariate analyses were then submitted to a multiple logistic regression analysis and associations were expressed as adjusted odds ratios (AOR) with 95%confidence interval. A p-value lower than 0. 05 was considered as significant. Before beginning the survey, ethical approvals were obtained from both the National Ethics Committee for Human Health Research (N°2015/01/543/CE/CNRESH/SP) in Cameroon, and the Institutional Review Board of the Université catholique de Louvain, Brussels campus in Belgium. Additionally, a Research Administrative Authorization was granted by the Cameroon Ministry of Public Health (N°631–1315). We also received approvals (verbal or written) from the Permanent Secretary of the National Onchocerciasis Control Program, the Regional Delegates of Public Health for the West, Centre and Littoral Regions, and the District Medical Officers of Bafang, Bafia and Yabassi. The chiefs of villages/communities were also met at the arrival of RA. Prior to each interview in the household, the RA obtained written consent of the household head or his representative as well as from the final respondent in the household. The chief of household was given the opportunity to choose the respondent, and the respondent was informed about his right to end the interview at any time.
Across the 3 HDs 1,378 households were identified, amongst which 89 (6. 5%) were excluded because of participation refusal. The main reasons of refusal were: busy schedule (going to farm, cooking), tiredness (coming from farm/work), or lack of interest on the study. Only 17 households (1. 2%) were excluded because of local language barriers. Among the 1,378 households 1,272 (92. 3%) were visited. One member per household was interviewed, making a final sample size of 1,272 individuals: 430 in Bafang, 421 in Bafia, and 421 in Yabassi. The median age (IQR) was 35 (24–50) years in Bafang, 40 (27–52) years in Bafia, and 37 (27–52) in Yabassi. Women were predominant in Bafang (57. 4%) but not in Bafia nor in Yabassi (46. 8% and 48. 7%, respectively); the other socio economical characteristics such as education, employment and length of stay in the villages are described in Table 1. The term “onchocerciasis” was not well known among the respondents in the 3 HDs: “onchocerciasis” was familiar to 47. 0% of them in Bafang, 63. 0% in Bafia and 66. 3% in Yabassi (p<0. 001). Moreover, more than one third of the respondents who knew the word “onchocerciasis” was unable to give/remember its definition (48. 5% in Bafang, 32. 5% in Bafia and 36. 2% in Yabassi). Three principal ways of defining onchocerciasis arose from respondents spontaneous answers. Firstly, people defined onchocerciasis by referring to its cause: for instance, disease caused by insects/mosquitoes/black fly bites or by dirt/dirty water. Secondly, onchocerciasis was defined by referring to its consequences: disease which causes skin/eye problems for instance, and thirdly, onchocerciasis was defined by its synonym: onchocerciasis is river blindness for example. “Filaria” or “filariasis” was cited by some respondents, either as a synonym or as a consequence of onchocerciasis.
After more than 15 years of fight against onchocerciasis with the CDTI strategy, there are still frequent misconceptions about onchocerciasis transmission and ivermectin efficacy. An unexpected misconception was observed predominantly in one health district, which is the belief of a causal link between onchocerciasis and high sugar intake. The strong association between this belief and ivermectin adherence raises the need of further studies to better understand its importance and features. Perceptions of CDTI program (CDD commitment, ivermectin MDA organization and perception of ivermectin effectiveness) appeared to have a stronger association with adherence. Therefore, in addition to education/sensitisation on onchocerciasis and ivermectin use, local health authorities should also emphasise on the implementation of the CDTI in the communities, with better population ownership and ensuring of good CDD work.
Onchocerciasis control in Africa has boomed with the ‘Community Directed Treatment with Ivermectin’ program. Successes of this program over many African countries prompted the international community to set it as main strategy for elimination of onchocerciasis and lymphatic filariasis. In Cameroon, onchocerciasis prevalence in some areas is still higher than what was predicted, despite more than 15 years of mass treatment. Therefore, in the frame of enlargement of the treatment zones, there is a need for enriching local literature on changeable factors that influence adherence to ivermectin. In this study, we assessed possible association between systematic ivermectin intake and people’s beliefs/perceptions of the disease and the program in three neighbouring regions of the country. Beliefs on onchocerciasis and their associations with adherence may differ from one community to another within the same area of the country. Furthermore, among all the factors related to disease and program representations that were studied, perceptions of ivermectin campaign’s organization and of community drug distributor’s commitment are the ones that were most determinant in adherence to ivermectin. Efforts should be done by health authorities in the program implementation inside the communities, with better population ownership and ensuring of good community drug distributors’ work.
medicine and health sciences
tropical diseases
geographical locations
census
parasitic diseases
health care
research design
filariasis
neglected tropical diseases
pharmacology
onchocerciasis
lymphatic filariasis
africa
research and analysis methods
public and occupational health
drug adherence
cameroon
computer and information sciences
health systems strengthening
hygiene
people and places
helminth infections
survey research
computer software
health care policy
Adherence to ivermectin is more associated with perceptions of community directed treatment with ivermectin organization than with onchocerciasis beliefs