Abstract: Objective To evaluate the efficiency of loop mediated isothermal amplification (LAMP) method in detecting DNA of Schistosoma japonicum eggs in fecal samples and its performance in field trial. Methods One gram of fresh fecal sample of an egg negative water buffalo was mixed with five S. japonicum eggs or 50 μl of egg secretion product (ESP) to simulate S. japonicum infection. DNA was extracted with a DNA kit from the fecal samples with addition of eggs, with or without a 2-min homogenization procedure, those with addition of ESP, and the negative fecal sample. LAMP was performed to amplify the 28S ribosomal DNA (rDNA) of S. japonicum to detect the DNA of eggs in fecal sample, and the efficacy was compared to that of PCR. In addition, a total of 221 wild fecal samples were collected from endemic areas in Hunan, Hubei, Jiangxi and Anhui provinces, and the DNA of field samples was extracted with a 2-min homogenization procedure, followed by LAMP and PCR respectively as above. The efficacy of LAMP in field application was compared with that of PCR and miracidia hatching test. Results The LAMP method showed the presence of S. japonicum eggs in the fecal samples added with eggs followed by a homogenization procedure, and the fecal sample with addition of ESP, as indicated by green color. Similar results were obtained by PCR. The positive rates of S. japonicum eggs in the wild fecal samples by LAMP, hatching method and PCR were 5.43% (12/221), 0.90% (2/221) and 4.52% (10/221), respectively. The sensitivity of LAMP was significantly higher than the hatching method (P < 0.05), and was comparable to that of the PCR method (P > 0.05). Conclusion LAMP method may be used as a sensitive testing tool in field detection of wild fecal in schistosomiasis endemic area.

Key words: Schistosoma japonicum, Egg, Nucleotide acid, Loop mediated isothermal amplification, Efficiency evaluation