Occurrence of Strongyloides stercoralis in Yunnan Province, China, and comparison of diagnostic methods

Abstract

Background: Strongyloides stercoralis is a neglected soil-transmitted helminth species, and there is a lack of parasitologic and epidemiologic data pertaining to this parasite in China and elsewhere. We studied the local occurence of S. stercoralis in a village in Yunnan province, China, and comparatively assesed the performance of different diagnostic methods. Methodology/Principal Findings: Multiple stool samples from a random population sample were subjected to the Kato-Katz method, an ether concentration technique, the Koga agar plate method, and the Baermann technique. Among 180 participants who submitted at least 2 stool samples, we found a S. stercoralis prevalence 11.7%. Males had a significantly higher prevalence than females (18.3% versus 6.1%, p = 0.011), and infections were absent in individuals < 15 years of age. Infections were only detected by the Baermann (highest sensitivity) and the Koga agar plate method, but neither with the Kato-Katz nor an ether-concentration technique. The examination of 3 stool samples rather than a single one resulted in the detection of 62% and 100% more infections when employing the Koga agar plate and the Baermann technique, respectively. The use of a mathematical model revealed a 'true' S. stercoralis prevalence in the currenlt setting of up to 16.3%. Conclusions/Significance: We conclude that S. stercoralis is endemic in the southern of Yunnan province and that differential diagnosis and integrated control of intestinal helminth infections needs more pointed emphasis in rural China. © 2007 Steinmann et al.