Spatio-temporal variations of emerging sites infested with schistosome-transmitting Oncomelania hupensis in Hunan Province, China, 1949–2016

Abstract

Background Constant emerging sites infested with Oncomelania hupensis (O. hupensis) impede the goal realization of eliminating schistosomiasis. The study assessed the spatial and temporal distributions of new Oncomelania snail habitats in Hunan Province from 1949 to 2016. Methods We used the data from annual snail surveys throughout Hunan Province for the period from 1949 to 2016. Global Moran’s I, Anselin local Moran’s I statistics (LISA) and a retrospective space-time permutation model were applied to determine the spatial and temporal distributions of emerging snail-infested sites. Results There were newly discovered snail-infested sites almost every year in 1949–2016, except for the years of 1993, 2009 and 2012. The number of emerging sites varied significantly in the five time periods (1949–1954, 1955–1976, 1977–1986, 1986–2003 and 2004–2016) (H = 25.35, p < 0.05). The emerging sites lasted 37.52 years in marshlands, 30.04 years in hills and 24.63 at inner embankments on average, with the values of Global Moran’s I being 0.52, 0.49 and 0.44, respectively. High-value spatial clusters (HH) were mainly concentrated along the Lishui River and in Xiangyin County. There were four marshland clusters, two hill clusters and three inner embankment clusters after 1976. Conclusions Lower reaches of the Lishui River and the Dongting Lake estuary were the high-risk regions for new Oncomelania snail habitats with long durations. Snail surveillance should be strengthened at stubborn snail-infested sites at the inner embankments. Grazing prohibition in snail-infested grasslands should be a focus in marshlands. The management of bovines in Xiangyin County is of great importance.

Cross-watershed distribution pattern challenging the elimination of Oncomelania hupensis, the intermediate host of Schistosoma japonicum, in Sichuan province, China

“…Furthermore, few snail habitats were observed in the riverbed of high-rank watercourses or big rivers in the present study located in the upper stream of the Yangtze River. This was much different from the middle and lower streams where many snail habitats were distributed in the marshlands in lake and river beds [ 43 , 44 ]. This may be explained by the slope and structure (rock) of riverbeds as well as runoff.…”

Unraveling the Variation Pattern of Oncomelania hupensis in the Yangtze River Economic Belt Based on Spatiotemporal Analysis

“…We chose the inverse distance method as the parameter for conceptualizing spatial relationships. The value of the global index Moran’s I ranges between −1 (maximum negative correlation) and 1 (maximum positive correlation), with a value of 0 indicating a random spatial distribution [ 16 , 17 ]. A test statistic Z-score larger than 1.96 or less than −1.96 and a two-side p -value less than 0.05 were considered statistically significant.…”

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

“…According to the WHO, 800 million people were at risk of infection and 241.3 million people required preventive chemotherapy (PC) in 2020 (Xu et al 2022). In China, schistosomiasis is caused by Schistosoma japonicum, with Oncomelania hupensis serving as the unique intermediate host (Li et al 2021), and is prevalent primarily in 12 provinces in the Yangtze River basin (Lu et al 2021). The Three Gorges Dam, a major water conservancy project, was officially commissioned in 2003 (Xiang et al 2021).…”