Three Gorges Dam: Influence of water quality on the density of schistosome-transmitting Oncomelania hupensis in the Dongting Lake Area, China

Abstract Schistosomiasis is a severe infectious disease and snails contribute to its transmission. Many factors, including water quality, affect the distribution of snails. This study collected the data on snails and indicators related to water quality in the Dongting Lake area from the period of 1998–2014. Water quality indexes such as permanganate index (CODMn), five-day biochemical oxygen demand (BOD5), total nitrogen (TN) and total phosphorus (TP) in correction with snail density were first examined using the Mann-Kendall (M-K) test. And then a Bayesian spatial-temporal model was constructed to evaluate the effect of water quality on snail density adjusting for meteorological factors and spatial-temporal variations. The results showed that the density of snails in the Dongting Lake area was influenced by water quality. The growth and reproduction of snails were promoted at a low pollution concentration, while inhibited at a high pollution concentration. These findings might provide valuable insights for relevant authorities to monitor the quality of water environment through investigating snail density.