Heckendorn F, N'Goran E K, Felger I, Vounatsou P, Yapi A, Oettli A, Marti H P, Dobler M, Traoré M, Lohourignon K L, Lengeler C
Swiss Tropical Institute, Department of Public Health and Epidemiology, P.O. Box, CH-4002 Basel, Switzerland.
Trans R Soc Trop Med Hyg. 2002 Sep-Oct;96(5):521-8. doi: 10.1016/s0035-9203(02)90426-8.
Entamoeba histolytica has been separated in recent years into 2 morphologically identical species: the apathogenic E. dispar and the pathogenic E. histolytica, only the latter being pathogenic. Although various laboratory techniques allow discrimination between the 2 species there is a lack of field data about the suitability of available diagnostic tests for use in epidemiological studies and few epidemiological studies using species-specific diagnosis have been performed at community level in endemic areas, especially in sub-Saharan Africa. We conducted a repeated cross-sectional study of 967 schoolchildren in central Côte d'Ivoire to compare and evaluate light microscopy, 2 different antigen detection assays, and one polymerase chain reaction (PCR) assay. Microscopy and a non-specific antigen capture Entamoeba enzyme-linked immunosorbent assay (ELISA) were used for the primary screening of all children (time t0). The prevalence of the E. histolytica/E. dispar species complex at t0 was 18.8% by single microscopical examination and 31.4% using the non-specific ELISA. Approximately 2 months after the initial screening, fresh stool specimens were collected on 2 consecutive days (t1 and t2) from (i) all the children who were positive by microscopy at t0 (n = 182) and (ii) 155 randomly selected children who were negative at the primary screening. These samples were tested with a second antigen detection ELISA specific for E. histolytica (n = 238) and with a species-specific PCR assay (n = 193). The second and third examinations (t1 and t2) revealed an additional 43 infections with the species complex E. histolytica/E. dispar, so that the cumulative microscopical prevalence for t1 and t2 was 27.7%. The overall prevalence of E. histolytica by species-specific ELISA antigen detection was low (0.83%), while the prevalence of E. dispar was 15%. When analysing only microscopically positive samples by PCR (n = 129), the ratio E. histolytica: E. dispar was very low (1:46), suggesting that the vast majority of Entamoeba infections in this area were apathogenic. Both species-specific tests performed well but the ELISA was easier to use for large-scale field screening.
近年来，溶组织内阿米巴已被分为两个形态相同的物种：非致病性的迪氏内阿米巴和致病性的溶组织内阿米巴，只有后者具有致病性。尽管各种实验室技术能够区分这两个物种，但缺乏关于现有诊断测试在流行病学研究中适用性的现场数据，并且在流行地区的社区层面，尤其是撒哈拉以南非洲地区，很少有使用物种特异性诊断的流行病学研究。我们对科特迪瓦中部的967名学童进行了一项重复横断面研究，以比较和评估光学显微镜检查、两种不同的抗原检测方法以及一种聚合酶链反应（PCR）检测方法。使用显微镜检查和一种非特异性抗原捕获溶组织内阿米巴酶联免疫吸附测定（ELISA）对所有儿童进行初次筛查（时间t0）。通过单次显微镜检查，t0时溶组织内阿米巴/迪氏内阿米巴物种复合体患病率为18.8%，使用非特异性ELISA时为31.4%。在初次筛查后约2个月，连续两天（t1和t2）从（i）所有在t0时显微镜检查呈阳性的儿童（n = 182）以及（ii）155名在初次筛查时呈阴性的随机选择儿童中收集新鲜粪便样本。这些样本用第二种针对溶组织内阿米巴的抗原检测ELISA（n = 238）和物种特异性PCR检测方法（n = 193）进行检测。第二次和第三次检查（t1和t2）发现另外43例溶组织内阿米巴/迪氏内阿米巴物种复合体感染，因此t1和t2时累计显微镜检查患病率为27.7%。通过物种特异性ELISA抗原检测，溶组织内阿米巴的总体患病率较低（0.83%），而迪氏内阿米巴的患病率为15%。仅通过PCR分析显微镜检查呈阳性的样本（n = 129）时，溶组织内阿米巴与迪氏内阿米巴的比例非常低（1:46），这表明该地区绝大多数溶组织内阿米巴感染是非致病性的。两种物种特异性检测方法表现良好，但ELISA更易于用于大规模现场筛查。
