Alemayehu Bereket, Tomass Zewdneh, Wadilo Fiseha, Leja Dawit, Liang Song, Erko Berhanu
Biomedical Sciences Division, Department of Biology, College of Natural and Computational Sciences, Wolaita Sodo University, Wolaita Sodo, Ethiopia.
Microbiology Unit, College of Health Sciences and Medicine, Wolaita Sodo University, Wolaita Sodo, Ethiopia.
BMC Public Health. 2017 Jun 20;17(1):587. doi: 10.1186/s12889-017-4499-x.
Intestinal helminth infections are major parasitic diseases causing public health problems in Ethiopia. Although the epidemiology of these infections are well documented in Ethiopia, new transmission foci for schistosomiasis are being reported in different parts of the country. The objective of this study was to assess the prevalence of Schistosoma mansoni and other intestinal helminth infections among school children and determine the endemicity of schistosomiasis in Wolaita Zone, southern Ethiopia.
Cross-sectional parasitological and malacological surveys were conducted by collecting stool samples for microscopic examination and snails for intermediate host identification. Stool samples were collected from 503 children and processed for microscopic examination using Kato-Katz and formalin-ether concentration methods. Snails collected from aquatic environments in the study area were identified to species level and Biomphalaria pfeifferi snails, the intermediate host of S. mansoni,, were individually exposed to artificial light in order to induce cercariae shedding. Cercariae shed from snails were used to infect laboratory-bred Swiss albino mice in order to identify the schistosome to species level.
The overall prevalence of intestinal helminth infections was 72.2% among school children. S. mansoni infection prevalence was 58.6%. The prevalence and intensity of S. mansoni infections varied among schools and sex of children. Swimming was the only factor reported to be significantly associated with S. mansoni infection (AOR = 2.954, 95% CI:1.962-4.449). Other intestinal helminth species identified were hookworms (27.6%), Ascaris lumbricoides (8.7%), E. vermicularis (2.8%), Taenia species (2.6%), T. trichiura (1.2%) and H. nana (0.6%). Only B. pfeifferi snails collected from streams shed schistosome cercariae and 792 adult S. mansoni worms were harvested from mice exposed to cercariae shed from B. pfeifferi on the 6th week post-exposure.
The present study found high level of intestinal helminth infections in the study area. The study also confirmed autochthonous transmission and endemicity of S. mansoni as evidenced by both parasitological and malacological findings as well as by further establishing infections in lab-bred mice. Therefore, there is a need to include the area in the control programs with anti-helminth drugs and also consider other complementary measures including sanitation, provision of clean water supply, and snail control.
肠道蠕虫感染是埃塞俄比亚导致公共卫生问题的主要寄生虫病。尽管这些感染的流行病学情况在埃塞俄比亚已有充分记录，但该国不同地区仍不断有血吸虫病新传播病灶的报告。本研究的目的是评估埃塞俄比亚南部沃莱塔地区学童中曼氏血吸虫及其他肠道蠕虫感染的患病率，并确定血吸虫病的流行情况。
通过采集粪便样本进行显微镜检查以及采集蜗牛以鉴定中间宿主，开展横断面寄生虫学和软体动物学调查。从503名儿童中采集粪便样本，并采用加藤厚涂片法和福尔马林 - 乙醚浓缩法进行显微镜检查。对从研究区域水生环境中采集的蜗牛进行种属鉴定，并将曼氏血吸虫的中间宿主菲氏双脐螺个体暴露于人工光照下以诱导尾蚴逸出。从蜗牛中逸出的尾蚴用于感染实验室饲养的瑞士白化小鼠，以鉴定血吸虫的种属。
学童中肠道蠕虫感染的总体患病率为72.2%。曼氏血吸虫感染患病率为58.6%。曼氏血吸虫感染的患病率和感染强度在不同学校及儿童性别之间存在差异。据报告，游泳是唯一与曼氏血吸虫感染显著相关的因素（比值比=2.954，95%置信区间：1.962 - 4.449）。鉴定出的其他肠道蠕虫种类有钩虫（27.6%）、蛔虫（8.7%）、蛲虫（2.8%）、带绦虫属（2.6%）、鞭虫（1.2%）和微小膜壳绦虫（0.6%）。仅从溪流中采集的菲氏双脐螺能逸出血吸虫尾蚴，在暴露后第6周，从暴露于菲氏双脐螺逸出尾蚴的小鼠体内收获了792条曼氏血吸虫成虫。
本研究发现研究区域肠道蠕虫感染水平较高。该研究还通过寄生虫学和软体动物学研究结果以及在实验室饲养小鼠中进一步证实感染，确认了曼氏血吸虫的本地传播和流行情况。因此，有必要将该地区纳入使用抗蠕虫药物的控制项目，并考虑其他补充措施，包括环境卫生、提供清洁水源和控制蜗牛。
