Is PCR the next reference standard for the diagnosis of schistosoma in stool? A comparison with microscopy in Senegal and Kenya

Background the current reference test for the detection of s. mansoni in endemic areas is stool microscopy based on one or more kato-katz stool smears. however,stool microscopy has several shortcomings that greatly affect the efficacy of current schistosomiasis control programs. a highly specific multiplex real-time polymerase chain reaction (pcr) targeting the schistosoma internal transcriber-spacer-2 sequence (its2) was developed by our group a few years ago,but so far this pcr has been applied mostly on urine samples. here,we performed more in-depth evaluation of the its2 pcr as an alternative method to standard microscopy for the detection and quantification of schistosoma spp. in stool samples. methodology/principal findings microscopy and pcr were performed in a senegalese community (n = 197) in an area with high s. mansoni transmission and co-occurrence of s. haematobium,and in kenyan schoolchildren (n = 760) from an area with comparatively low s. mansoni transmission. despite the differences in schistosoma endemicity the pcr performed very similarly in both areas; 13–15% more infections were detected by pcr when comparing to microscopy of a single stool sample. even when 2–3 stool samples were used for microscopy,pcr on one stool sample detected more infections,especially in people with light-intensity infections and in children from low-risk schools. the low prevalence of soil-transmitted helminthiasis in both populations was confirmed by an additional multiplex pcr. conclusions/significance the its2-based pcr was more sensitive than standard microscopy in detecting schistosoma spp. this would be particularly useful for s. mansoni detection in low transmission areas,and post-control settings,and as such improve schistosomiasis control programs,epidemiological research,and quality control of microscopy. moreover,it can be complemented with other (multiplex real-time) pcrs to detect a wider range of helminths and thus enhance effectiveness of current integrated control and elimination strategies for neglected tropical diseases. © 2015,plos neglected tropical diseases. all rights reserved.