Wanji Samuel, Kengne-Ouafo Jonas A, Esum Mathias E, Chounna Patrick W N, Adzemye Bridget F, Eyong Joan E E, Jato Isaac, Datchoua-Poutcheu Fabrice R, Abong Raphael A, Enyong Peter, Taylor David W
Parasite and Vectors Research Unit, Department of Microbiology and Parasitology, University of Buea, P.O.Box 63, Buea, Cameroon.
Research Foundation for Tropical Diseases and Environment, P.O.Box 474, Buea, Cameroon.
Parasit Vectors. 2015 Dec 30;8:667. doi: 10.1186/s13071-015-1283-6.
Onchocerciasis control for years has been based on mass drug administration (MDA) with ivermectin (IVM). Adherence to IVM repeated treatment has recently been shown to be a confounding factor for onchocerciasis elimination precisely in rain forest areas where transmission continues and Loa loa co-exists with Onchocerca volvulus. In this study, participants' oral declarations were used as proxy to determine the relationship between adherence to IVM treatment and parasitological indicators of onchocerciasis in the rain forest area of Cameroon with more than a decade of MDA.
Participants were recruited based on their IVM intake profile with the aid of a semi-structured questionnaire. Parasitological examinations (skin sniping and nodule palpation) were done on eligible candidates. Parasitological indicators were calculated and correlated to IVM intake profile.
Of 2,364 people examined, 15.5% had never taken IVM. The majority (40.4%) had taken the drug 1-3 times while only 18% had taken ≥ 7 times. Mf and nodule prevalence rates were still high at 47%, 95% CI [44.9-49.0%] and 36.4%, 95% CI [34.4-38.3%] respectively. There was a treatment-dependent reduction in microfilaria prevalence (rs =-0.986, P = 0.01) and intensity (rs =-0.96, P = 0.01). The highest mf prevalence (59.7%) was found in the zero treatment group and the lowest (33.9%) in the ≥ 7 times treatment group (OR = 2.8; 95% CI [2.09-3.74]; P < 0.001). Adults with ≥ 7 times IVM intake were 2.99 times more likely to have individuals with no microfilaria compared to the zero treatment group (OR = 2.99; 95% CI [2.19-4.08], P < 0.0001). There was no clear correlation between treatment and nodule prevalence and intensity.
Adherence to ivermectin treatment is not adequate in this rain forest area where L. loa co-exists with O. volvulus. The prevalence and intensity of onchocerciasis remained high in individuals with zero IVM intake after more than a decade of MDA. Our findings show that using parasitological indicators, reduction in prevalence is IVM intake-dependent and that participants' oral declaration of treatment adherence could be relied upon for impact studies. The findings are discussed in the context of challenges for the elimination of onchocerciasis in this rain forest area.
多年来，盘尾丝虫病的防治一直基于使用伊维菌素（IVM）进行大规模药物治疗（MDA）。最近发现，在盘尾丝虫病传播仍在继续且罗阿丝虫与盘尾丝虫共存的热带雨林地区，坚持重复使用IVM治疗恰恰是盘尾丝虫病消除工作中的一个混杂因素。在本研究中，在喀麦隆热带雨林地区开展了十多年的MDA之后，通过参与者的口头声明来推断坚持IVM治疗与盘尾丝虫病寄生虫学指标之间的关系。
借助半结构化问卷，根据参与者的IVM摄入情况招募参与者。对符合条件的候选人进行寄生虫学检查（皮肤 snipping 和结节触诊）。计算寄生虫学指标并将其与IVM摄入情况相关联。
在接受检查的2364人中，15.5%的人从未服用过IVM。大多数人（40.4%）服用过1 - 3次该药物，而只有18%的人服用过≥7次。微丝蚴和结节患病率仍然很高，分别为47%，95%CI[44.9 - 49.0%]和36.4%，95%CI[34.4 - 38.3%]。微丝蚴患病率（rs = -0.986，P = 0.01）和强度（rs = -0.96，P = 0.01）呈现出与治疗相关的下降。微丝蚴患病率最高（59.7%）出现在未接受治疗组，最低（33.9%）出现在≥7次治疗组（OR = 2.8；95%CI[2.09 - 3.74]；P < 0.001）。与未接受治疗组相比，IVM摄入≥7次的成年人无微丝蚴个体的可能性高2.99倍（OR = 2.99；95%CI[2.19 - 4.08]，P < 0.0001）。治疗与结节患病率和强度之间没有明显的相关性。
在罗阿丝虫与盘尾丝虫共存的这片热带雨林地区，伊维菌素治疗的依从性不足。在开展了十多年的MDA之后，未服用过IVM的个体中盘尾丝虫病的患病率和强度仍然很高。我们的研究结果表明，利用寄生虫学指标，患病率的降低依赖于IVM的摄入，并且参与者关于治疗依从性的口头声明可用于影响研究。在这片热带雨林地区盘尾丝虫病消除面临的挑战背景下对这些研究结果进行了讨论。
