Objective: To explore the approach and tool for surveillance and forecast of schistosomiasis, so as to provide scientific evidence for improving the sensitivity of the surveillance and forecast system of schistosomiasis.
Methods: Two field detections were carried out in June and September by using the determination of sentinel mice in key high-risk water regions of 7 provinces of Hunan, Hubei, Jiangxi, Anhui, Jiangsu, Yunnan and Sichuan, and the sentinel mice were raised in laboratory and dissected for observation of schistosome infections. The database regarding schisosome infections in key water regions of China was established, and the tempo-spatial distribution and environmental features of the national surveillance and forecast sites with positive sentinel mice were analyzed.
Results: A total of 72 surveillance and forecast sites were detected in 34 counties (cities, districts) of 7 provinces. Of the 2 667 sentinel mice placed, 2 613 were recovered, with a recovery rate of 97.98%. Among the 72 sites detected, 17 were detected with positive sentinel mice, and the occurrence rate of positive sites was 23.61%. The occurrence rate was 17.24% (10/58) in June and 14.71% (10/68) in September, and no significant difference was observed between two batches (chi2 = 0.151, P = 0.698). Of the 2 436 sentinel mice dissected, 90 were positive, and 459 schistosome worms were collected, with a total infection rate of 3.69%, and the mean worm burdens of positive mice were 5.10 worms per mouse. The infection rate of sentinel mice was 2.82% (31/1 099) in June and 4.41% (58/1 337) in September, the infection rate of sentinel mice was significantly higher in September than that in Juen (chi2 = 14.681, P < 0.01), and the mean worm burdens of infected sentinel mice were 2.45 worms per mouse in June and 6.49 worms per mouse in September. The occurrence rates of the positive sites with infected snails detected in the study year, last year and without infected snails detected in recent 3 years were 29.63%, 41.67% and 12.12%, respectively, and no significant differences were detected (chi2 = 5.227, P = 0.071). The infection rates of sentinel mice in the aforementioned 3 settings were 9.38%, 3.98% and 0.59%, respectively, and there was significant difference observed (chi2 = 20.489, P < 0.01).
Conclusions: The monitoring results of sentinel mice infections in key water regions can almost reflect the endemic situation of schistosomiasis in local areas. Notably, many infections are detected in settings without infected snails detected in recent years. The monitoring of sentinel mice infections could significantly improve the sensitivity of the surveillance and forecast system of schistosomiasis.