Familial aggregation of human helminth infection in the Poyang lake area of China with a focus on genetic susceptibility to schistosomiasis japonica and associated markers of disease

Human helminthiases are common in China, especially in rural areas where sanitation conditions are poor. Soiltransmitted helminths (STHs) are predominantly found in the southern provinces. Schistosoma japonicum is also endemic to southern China. Here we review the prevalence of helminth infections and polyparasitism in China, and discuss the interactions between helminth parasites in the co-infected host. It is clear that STHs are more prevalent in rural China than previously suggested emphasizing the need for systematic control of STHs. Further, the need for improved sanitation and hygiene conditions to prevent parasite transmission is highlighted. We provide supporting evidence for human genetic susceptibility to both single helminth infection and polyparasitism, and suggest that susceptibility to helminths infections may not be independent of one or the other. We demonstrate an association between single nucleotide polymorphism (SNP) variants in IL-5 and symptomatic S. japonicum infection and discuss the potential role of IL-5 in other helminth infections. Fundamental to disease and morbidity control is adequate and effective diagnosis and surveillance of disease. We discuss the role of sICAM-1 and TNFR-I and -II as candidate markers for schistosome-induced hepatomegaly and fibrosis, and their potential for assessing disease stage and progression in schistosomiasis.