Abstract:As the only intermediate host of Schistosoma japonicum, Oncomelania hupensis plays an irreplaceable role in the prevalence of schistosomiasis japonica. Several living subspecies of Oncomelania hupensis are found in Asia, especially in China, Japan,the Philippines, and Sulawesi of Indonesia. The existing geographical distribution pattern of O. hupensis has been influenced by geological events. This study used existing mitochondrial gene data for O. hupensis in the GenBank database and the molecular clock method to estimate the divergence time of each subspecies of O. hupensis. For the first time, the timing and causes of the distribution pattern of the different O. hupensis subspecies were studied by combining molecular data with data on geologic events. The results showed that the uplift and isolation of the Qinghai-Tibet Plateau caused Oncomelania hupensis robertsoni to differentiate 4.76 Ma(Million anniversary), while Oncomelania hupensis guangxiensis was affected by the third Himalayan orogenic movement, differentiating 1.10 Ma. Oncomelania hupensis nosophora was influenced by the formation of the Yonaguni Strait and diverged 1.43 Ma. Influenced by ice ages and interglacial periods, Oncomelania hupensis tangi and Oncomelania hupensis formosana diverged 0.57 Ma. The link of the ancient Yangtze River promoted the spread of O. hupensis to the middle and lower reaches of the Yangtze River, and the developed water network facilitated gene exchange among Oncomelania hupensis hupensis in the area. Eventually, 0.62 Ma, O. h. hupensis differentiated.Author summaryPhylogenetic analysis of Pomatiopsidae species showed that Oncomelania was isolated from other genera and clustered independently in phylogenetic trees. Further analysis of the species Oncomelania hupensis and its subspecies was performed. The snail species O. hupensis has multiple subspecies that exhibit certain differences. These subspecies are distributed across Asia, from China’s Yunnan Province in the west to Japan in the east and south to the Philippines and Indonesia. In addition, the subspecies are widespread in the middle and lower reaches of the Yangtze River in China, and the distribution ranges of the different subspecies do not overlap. The formation of this distribution pattern of each subspecies of O. hupensis has a profound impact on the prevalence of Schistosoma japonicum. Therefore, the authors analyzed molecular data and geological historical events to investigate the timing and causes of the distribution pattern of each subspecies of O. hupensis.
Population Genetics of Schistosoma japonicum within the Philippines Suggest High Levels of Transmission between Humans and Dogs