Spatial distribution and habitat suitability of Biomphalaria straminea, intermediate host of Schistosoma mansoni, in Guangdong, China

Abstract

BackgroundBiomphalaria straminea is an invasive vector in China, posing a significant threat to public health. Understanding the factors affecting the establishment of this snail is crucial to improve our ability to manage its dispersal and potential risk of schistosomiasis transmission. This study sought to determine the spatial distribution of B. straminea in mainland China and whether environmental factors were divergent between places with and without B. straminea.MethodsA malacological survey of B. straminea was conducted in Guangdong Province, China. Snails were identified using anatomical keys. Water and sediment samples were taken, and their physicochemical properties were analyzed using national standard methods. Landscape and climatic variables were also collected for each site. We compared the environmental characteristics between sites with and without B. straminea using Mann-Whitney U test. We further used generalized linear mixed models to account for seasonal effects.ResultsB. straminea was found at six sites, including one in Dongguan and five in Shenzhen. Probability map found a hot spot of B. straminea distribution at Shenzhen and Hong Kong. Sites occupied by B. straminea were characterized by higher median altitude, mean annual precipitation and moderate temperature. Water with snails had higher median concentrations of total nitrogen, nitrate and nitrites, ammoniacal nitrogen, calcium, zinc and manganese but lower dissolved oxygen and magnesium. Sediments with snails had higher median copper, zinc and manganese. B. straminea was associated with maximum temperature of the warmest month (pMCMC < 0.001) and sediment zinc (pMCMC < 0.001).ConclusionsB. straminea is distributed in Shenzhen and its surrounding areas in Guangdong, China. Sites with and without B. straminea differed in the maximum temperature of the warmest month and sediment zinc. Surveillance should be continued to monitor the dispersal of this snail in China.Electronic supplementary materialThe online version of this article (10.1186/s40249-018-0492-6) contains supplementary material, which is available to authorized users.

Imported Schistosomiasis: A New Public Health Challenge for China

“…The snail Biomphalaria straminea, the intermediate host of S. mansoni, has been identified in Hongkong since 1974 and in Shenzhen since 1981 (58,59). The existence of B. straminea was even observed in Dongguan and Huizhou regions in Guangdong Province (6,60). The existence of intermediate host B. straminea and the imported cases of S. mansoni infection could cause the spread of infection and make such endemic in the area.…”

“…Based on the database of the National Notifiable Disease Report System (NNDRS), there had been 355 cases of imported schistosomiasis cases reported in 15 provinces (autonomous region, municipalities) in China from 1979 to 2019, including 78 cases infected with S. mansoni, 262 cases with S. haematobia, and 15 cases with unidentified Schistosoma species (5). Due to the existence of the snail Biomphalaria straminea, an intermediate host of S. mansoni, being already found in Guangdong province in south China, the imported S. mansoni increases the risk of its transmission in China (6). To better understand imported schistosomiasis for better diagnosis and treatment and to get prepared for their possible transmission in China, we reviewed and analyzed the clinical features and the characterization of imported schistosomiasis since 1979, including 78 cases of imported schistosomiasis mansoni and 262 cases of schistosomiasis haematobia.…”

Surveillance on schistosomiasis in five provinces of the People’s Republic of China in the post-elimination era

“…The development of new snail habitats and snails reappeared in former snail habitats in four provinces except Guangdong Province, providing evidence that eliminating oncomelanid snails completely was quite di cult. Although Guangdong Province kept the achievement with no oncomelanid snails detected, a new challenge for Guangdong Province is the invasion and spread of Biomphalaria Strami [33].…”

Currently Available Monitoring and Surveillance Systems for Taenia spp., Echinococcus spp., Schistosoma spp., and Soil-Transmitted Helminths at the Control/Elimination Stage: A Systematic Review

“…Furthermore, water and sediment samples in addition to landscape and climatic data from the study sites were collected and analyzed in order to estimate the relationship between the presence of B. straminea and environmental and physicochemical variables. This survey revealed the wide distribution of this snail and a correlation with water temperature and physicochemical properties of sediments (i.e., sediment zinc and water temperature were higher in places with B. straminea), meaning that the monitoring of the dispersal and infection rate of this snail must be continued [13]. Further detailed descriptions of malacological surveys, incorporated in an integrated surveillance system, are discussed below (Section 3.1.6).…”