[Survey of snail distribution in Four-lake Basin of Hubei Province].

Objective: To investigate the distribution of Oncomelania snails in Four-Lake Basin of Hubei Province, so as to provide scientific evidence for the development of snail control interventions.
Methods: The snail distribution was surveyed by means of the retrospective study and cross-sectional survey in the Four-Lake Basin in Spring of 2016. The data pertaining to the endemic situation of schistosomiasis were collected and analyzed in the Four-Lake Basin from 2008 to 2018, and the associations of snail habitat areas with the prevalence of Schistosoma japonicum in humans and bovines were examined.
Results: There were 16 003 snail habitats in the 9 schistosomiasis-endemic counties (districts) in the Four-Lake Basin in 2016, covering an area of 246 million m ² . The mean density of living snails was 0.622 5 snails/0.1 m ² , which was relatively high in weed-type settings (0.688 0 snails/0.1 m ² ) and ditches (0.706 4 snails/0.1 m ² ). Type I (current snail habitats, 53.03%) and Ⅱ- Ⅳ (historical snail habitats, 46.97%) settings were predominant snail habitats. A big change was seen in snail habitats in dry farmland, marshland and paddy farmland, and environmental modification resulted in satisfactory snail control effectiveness. In addition, the area of snail habitats positively correlated with the changes in the prevalence of S. japonicum infections in humans ( r = 0.842, P < 0.01) and livestock ( r = 0.695, P < 0.01).
Conclusions: The integrate strategy with an emphasis on the control of the source of S. japonicum infections results in remarkable snail control effectiveness in the Four-Lake Basin; however, there is a risk of re-emerging snail habitats.