Abstract
BackgroundDespite their wide occurrence, cryptosporidiosis and giardiasis are considered neglected diseases by the World Health Organization. The epidemiology of these diseases and microsporidiosis in humans in developing countries is poorly understood. The high concentration of pathogens in raw sewage makes the characterization of the transmission of these pathogens simple through the genotype and subtype analysis of a small number of samples.Methodology/Principal FindingsThe distribution of genotypes and subtypes of Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi in 386 samples of combined sewer systems from Shanghai, Nanjing and Wuhan and the sewer system in Qingdao in China was determined using PCR-sequencing tools. Eimeria spp. were also genotyped to assess the contribution of domestic animals to Cryptosporidium spp., G. duodenalis, and E. bieneusi in wastewater. The high occurrence of Cryptosporidium spp. (56.2%), G. duodenalis (82.6%), E. bieneusi (87.6%), and Eimeria/Cyclospora (80.3%) made the source attribution possible. As expected, several human-pathogenic species/genotypes, including Cryptosporidium hominis, Cryptosporidium meleagridis, G. duodenalis sub-assemblage A-II, and E. bieneusi genotype D, were the dominant parasites in wastewater. In addition to humans, the common presence of Cryptosporidium spp. and Eimeria spp. from rodents indicated that rodents might have contributed to the occurrence of E. bieneusi genotype D in samples. Likewise, the finding of Eimeria spp. and Cryptosporidium baileyi from birds indicated that C. meleagridis might be of both human and bird origins.Conclusions/SignificanceThe distribution of Cryptosporidium species, G. duodenalis genotypes and subtypes, and E. bieneusi genotypes in urban wastewater indicates that anthroponotic transmission appeared to be important in epidemiology of cryptosporidiosis, giardiasis, and microsporidiosis in the study areas. The finding of different distributions of subtypes between Shanghai and Wuhan was indicative of possible differences in the source of C. hominis among different areas in China.
Highlights
Cryptosporidium, Giardia, and microsporidia infections are significant causes of diarrhea in humans worldwide [1,2]
The epidemiology of cryptosporidiosis, giardiasis, and microsporidiosis is poorly understood in developing countries despite their wide occurrence
We have examined the distribution of the pathogens for these neglected diseases in domestic wastewater samples from four major cities (Shanghai, Nanjing, Qingdao, and Wuhan) at genotype and subtype levels to infer the extent of their transmission in urban areas in China and likely infection sources in humans
Summary
Cryptosporidium, Giardia, and microsporidia infections are significant causes of diarrhea in humans worldwide [1,2] Despite their wide occurrence, cryptosporidiosis and giardiasis are considered neglected diseases by the World Health Organization, largely due to a lack of studies in developing countries [3]. The host-adaptive nature of different species/genotypes of these parasites helps us understand the potential infection sources and transmission routes of the disease. Giardiasis in humans and most other mammals is caused by Giardia duodenalis Despite their wide occurrence, cryptosporidiosis and giardiasis are considered neglected diseases by the World Health Organization. Cryptosporidiosis and giardiasis are considered neglected diseases by the World Health Organization The epidemiology of these diseases and microsporidiosis in humans in developing countries is poorly understood. The high concentration of pathogens in raw sewage makes the characterization of the transmission of these pathogens simple through the genotype and subtype analysis of a small number of samples
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