Epidemiological study on Clonorchis sinensis infection in Shenzhen area of Zhujiang delta in China

Abstract

To study the transmission route and epidemiological features of Clonorchis sinensis infection in Shenzhen area, which is the biggest immigration city in the south of China, we examined 1,473 individuals (710 males and 763 females) to assess the current status of C. sinensis infection among the people in a village of Shenzhen in Zhujiang delta of Guangdong province, China. Freshwater snails, 630, of different species known as the first intermediate host of C. sinensis were collected and examined for cercaria infection, and 430 freshwater fishes of different species as the second intermediate host were examined for metacercaria infection. Among 1,473 people examined, 70 (4.75%) were found infected with C. sinensis. By counting eggs per gram feces (EPG), it was found that the intensity of infection in males was stronger than that of females, and the average EPG was 41.87 in all population. Snails, 1.15%, were infected with cercariae of C. sinensis. The average infection rate of freshwater fishes of 15 species with metacercariae of C. sinensis was 16.97%, and the carps reached the highest infection rate (40.74%). A questionnaire was designed with 12 questions covering socioeconomic conditions and human behavior, contamination of the environment, and fishponds. Of 1,473 interviewees, 54% did not know about fluke disease or its transmission route, 12% of those who knew about the fluke believed that the infection causes no harm or only slight harm to their health. Of the interviewees, 27%, ate raw fish at least one to two times per month. Of families, 5% used the same utensils for both raw fish and cooked food. Of the fishpond owners, 40% fed their fishes with feces of domestic animals and humans. All these factors of unhealthy behaviors, poor knowledge, inappropriate farming/fishery practices, and eating raw fish have made the prevalence of clonorchiasis increase in humans in the Shenzhen area. It is urgent to perform a control program, including health education, environmental modification, reform of traditional farming/fishery practice, mass screening, and chemotherapy for humans, and the management of domestic animals to decrease C. sinensis infection in the human population in Shenzhen.

Epidemiological investigation of Clonorchis sinensis infection in freshwater fishes in the Pearl River Delta

“…These species are closely related to C. sinensis infection of the residents in the Pearl River Delta. For this reason, our investigation put emphasis on the infection status of the two kinds of fishes, and its result showed that the mean infection rates of C. idellus and H. nobilis reached 52.42% and 21.65%, respectively, which were higher than those reported by previous studies (Wang et al 2002;Chen et al 1997;Zhang et al 2007). Additionally, the infection rate of C. idellus was higher than that of H. nobilis (χ 2 = 346.2, P<0.005), indicating that the C. idellus was more prone to C. sinensis infection.…”

Global status of fish-borne zoonotic trematodiasis in humans

“…The Zhang et al 2007). The release of cercariae from snails is high and occurs over a fairly long period thus ensuring propagation (Keiser and Utzinger 2009;Mas-Coma and Bargues 1997).…”

Sensitive and rapid detection of Clonorchis sinensis infection in fish by loop-mediated isothermal amplification (LAMP)

“…C. sinensis metacercariae were collected from fish (Pseudorasbora parva) muscles essentially according to a previously reported method (Zhang et al 2007). Several trematodes infecting humans were included as 'heterologous control samples' for assessing the specificity of the LAMP assay, namely, Opisthorchis viverrini, Fasciola hepatica, Fasciola gigantica, Schistosoma mansoni, and Schistosoma japonicum.…”