Christensen E E, Taylor M, Zulu S G, Lillebo K, Gundersen S G, Holmen S, Kleppa E, Vennervald B J, Ndhlovu P D, Kjetland E F
Norwegian Centre for Imported and Tropical Diseases, Department of Infectious Diseases Ullevaal, Oslo University Hospital; and Faculty of Medicine, University of Oslo, Norway.
S Afr Med J. 2018 Mar 28;108(4):352-355. doi: 10.7196/SAMJ.2017.v108i4.12775.
A predominant feature of Schistosoma haematobium infection is urinary egg excretion, and microscopic egg detection remains the accepted standard field diagnostic tool. Praziquantel is the drug of choice for schistosomiasis, and the World Health Organization recommends that it should be administered to all children >4 years of age living in schistosomiasis-endemic areas. The frequency of mass drug administration depends on the prevalence rate in the community. Urinary schistosome egg output has a day-to-day and hour-to-hour intrasubject variation. Therefore, it is important to assess possible seasonal variations in egg excretion to improve the planning of drug treatment.
To assess the influence of seasonality on urinary schistosome egg excretion in South Africa (SA).
We performed a prospective cohort study, exploring seasonal variations of S. haematobium egg excretion in 184 girls aged 10 - 12 years from randomly selected schools in a rural area of KwaZulu-Natal Province, SA. The area has a subtropical climate characterised by a cool dry season and a hot humid season. For children, water contact is higher in the latter season. At baseline, 108 girls were examined in the hot season, and 76 in the cold season. In the next year's cold season the untreated patients were re-investigated before treatment.
There was a decrease in infection in the group initially tested in the hot season compared with the group tested in the cold season at both time points when adjusted for age and water contact (adjusted odds ratio 3.61 (95% confidence interval 1.14 - 11.44); p=0.03).
This unique study shows that schistosomiasis prevalence determined by microscopy exhibits seasonal variation, with a higher prevalence in the hot rainy season. Precise community prevalence estimations are key in decisions to treat communities. There was significantly lower egg output in the cold season, and sampling in that season may therefore underestimate the prevalence of urinary schistosomiasis. The study indicates that sampling in SA should be done in the hot season.
埃及血吸虫感染的一个主要特征是尿中虫卵排泄，而显微镜下虫卵检测仍是公认的标准现场诊断工具。吡喹酮是治疗血吸虫病的首选药物，世界卫生组织建议对生活在血吸虫病流行地区所有4岁以上儿童使用该药。群体药物管理的频率取决于社区的患病率。尿中血吸虫卵排出量存在个体内每日和每小时的变化。因此，评估虫卵排泄可能存在的季节性变化对于改进药物治疗计划很重要。
评估季节性对南非尿中血吸虫卵排泄的影响。
我们进行了一项前瞻性队列研究，探讨来自南非夸祖鲁-纳塔尔省农村地区随机选择学校的184名10 - 12岁女孩埃及血吸虫卵排泄的季节性变化。该地区属亚热带气候，特点是凉爽干燥季节和炎热潮湿季节。对儿童来说，后一个季节的水接触更多。基线时，108名女孩在炎热季节接受检查，76名在寒冷季节接受检查。在次年寒冷季节，对未治疗的患者在治疗前再次进行调查。
在调整年龄和水接触因素后，与寒冷季节检测的组相比，最初在炎热季节检测的组在两个时间点的感染率均有所下降（调整后的优势比为3.61（95%置信区间1.14 - 11.44）；p = 0.03）。
这项独特的研究表明，通过显微镜检查确定的血吸虫病患病率呈现季节性变化，在炎热多雨季节患病率较高。准确的社区患病率估计是决定社区治疗的关键。寒冷季节的虫卵排出量明显较低，因此在该季节采样可能会低估尿血吸虫病的患病率。该研究表明，在南非应在炎热季节进行采样。
