A highly sensitive TaqMan real-time PCR assay for early detection of Schistosoma species.

Schistosomiasis is a major infectious disease and a public health concern in many areas in China and other countries. Sensitive method for detection of the parasite is critical for early diagnosis and for monitoring of effective treatment of the disease. In this study, we developed a highly sensitive TaqMan real-time PCR assay for the detection of Schistosoma japonicum DNA in mouse feces and serum samples. This assay was based on the DNA sequence of the S. japonicum 18S rRNA gene and was able to detect 10 fg of S. japonicum genomic DNA, which is 100 times more sensitive than conventional PCR. We were able to detect the S. japonicum DNA one week post-infection in mouse sera and 4 weeks post-infection in feces, which was one week earlier than egg detection by microscopy in feces. This assay was also highly specific for Asian Schistosomes which are causative species of human Schistosomiasis. In single sex male cercariae infected mice, parasite DNA was only detected in the first 4 weeks post-infection, suggesting that the DNA was derived from decaying worms' corpse in the first 4 weeks whereas the DNA was mainly from decaying parasite eggs afterwards. Therefore we conclude that the established TaqMan real-time PCR assay is a sensitive, specific and convenient method that could be used for the early diagnostic evaluation of S. japonicum infection in humans and for monitoring outbreaks in endemic areas with low prevalence.