Changes of serum anti-schistosome antibody levels in schistosomiasis japoni-ca patients after treatment

OBJECTIVE: To investigate the changes of serum anti-schistosome antibody titers in schistosomiasis japonica patients after treatment, in order to provide the evidence for formulating the schistosomiasis surveillance program in marshland and lake regions. METHODS: Upon prospective cohort study, the stool examination positive schistosomiasis patients and blood examination positive suspected patients (the titer was more than 1:80, including 1:80) were selected as the research objects in Jiangling County in 2014, and they received the 2-day praziquantel therapy. Half year, one year and two years after the treatment, their blood samples and fecal samples were collected for IHA anti-schistosome antibody detections and schistosome egg and miracidium detections. RESULTS: In 2014, the stool examination positives were 251, and the majority of them were over 41 years old, accounting for 93.23% (234/251) ; 581 cases of high antibody titers were detected by the IHA method, and the majority of them were over 41 years old, accounting for 89.16% (518/581) . Half year, one year and two years after the treatment, among the stool examination positives, the negative conversion rates of stool positives were 99.60% (250/251), 100% (239/239) and 100% (234/234) respectively and the negative conversion rates of antibody positives were 21.91% (55/251), 64.11% (156/239) and 76.89% (193/234) respectively. In the high antibody titer positives, the negative conversion rates were 38.04% (221/581), 64.11% (359/560), and 77.86% (429/551) respectively, Half year, one year and two years after the treatment. There were statistically significant differences among the antibody negative conversion rates by χ2 test (χ2 = 77.538, 183.412, 25.469 respectively, all P < 0.001) . The geometric mean values of antibody titers of different durations between 2 groups were analyzed by 2-independent-samples T test, and the geometric mean values of antibody titers between the 2 groups were different before the treatment (t = 23.576, P < 0.01), but the geometric mean values of antibody titers between the 2 groups were not different 6 months, 1 year and 2 years after the treatment (t = -0.046, 1.165, -0.132, P = 0.964, 0.245, 0.895 respectively). CONCLUSIONS: The levels of serum anti-schistosome antibody degrade slowly in schistosomiasis japonica patients after the treatment, and the results of IHA tests cannot distinguish the current schistosome infection from previous schistosome infection. Therefore, it is necessary to develop the specific diagnostic technology for schistosome infection in order to meet the need of monitoring.