BACKGROUND: The prevalence and intensity of schistosomiasis infection in China has decreased markedly in recent years. Therefore, more accurate methods are critically needed to ensure further control of low-intensity schistosomiasis infection. For chronic schistosomiasis patients, the detection of schistosome eggs in colorectal mucosa tissues is commonly used. This work aimed to explore differences in sensitivity of the Schistosoma japonicum (S. japonicum) retrotransposon (SjR2) gene in colon tissue from S. japonicum infected hosts and to develop an ideal method for genetic diagnosis of low-intensity schistosomiasis.

MATERIAL AND METHODS: Serum and colon samples were collected from mice at different time points, either post-infection (PI) or post-treatment (PT). Colorectal biopsy specimens from outpatients with schistosomiasis were collected. All samples from mice and patients, including serum as well as colon tissue containing eggs and tissue containing no eggs, were examined using the polymerase chain reaction technique.

RESULTS: The results showed that the SjR2 gene could be detected in all colon tissue containing at least one egg, except for when the egg was completely degraded. The positive rate of gene detection in serum was low. The results from egg-free colon tissue from around the eggs were more consistent with the actual parasitism in vivo.

CONCLUSIONS: The results indicate that detection of the gene in colon tissue located within a 0.5 cm distance from the eggs would be a practical and ideal method for genetic diagnosis of schistosomiasis. After the colorectal biopsy, this method can be a sensitive assisted examination to the clinical diagnosis of low-intensity schistosomiasis infection.

Keywords: Diagnosis, Schistosomiasis, Schistosomiasis japonica, Biopsy, Colon, Feces, Intestinal Mucosa, Polymerase Chain Reaction, Schistosoma japonicum