Abstract:

Objective To analyze the dynamic change and the factors that effect on the imported schistosomiasis case since the disease transmission blocking criteria have been met in Zhejiang Province in 1995. Methods Data for the imported case of schistosomiasis and snail investigation in Zhejiang Province from 1996 to 2017 were collected and analyzed retrospectively for the case distribution, diagnosis, treatment and for snail ridden area. Results Totally 245 cases of imported schistosomiasis were reported in 30 counties in Zhejiang Province from 1996-2017, including 41 cases of acute Schistosoma japonicum infection. Among them, 241 cases were imported from other provinces in China, mainly from neighboring Jiangxi (37.3%, 90/241） and Anhui (29.9%, 72/241). Four of them were imported from Nigeria in Africa including 3 cases of S. haematobium and 1 case of S. mansoni infections. The number of imported cases was increased in the years before 2005 with up to 40 cases in 2005, and then gardually to decreased. More cases were reported in the second half of each year (80.8%, 198/245). The imported cases were reported in total 30 counties (cities, district) in the province, most of them (230) were reported in 25 counties in the 8 historially endemic cities, and Ningbo had the largest number of imported cases (55.9%, 137/245) followed by Hangzhou (18.4%, 45/245) and Quzhou (6.9%, 17/245). Among the total 245 cases, 180 were males and 65 females. More cases were found in those with low education (29.8% with primary school and 49.4% with junior high school) and with blue collar occupations (farmers 42.0%, workers 23.3%) and in students (14.7%). Of the 241 cases imported from other provinces, 85.1% (205/241) cases were infected from uncontrolled or re-emerging endemic areas. Most cases were infected by the contact with contaminated water during swimming (37.1%) or agricultural practices (36.3%). More cases were identified by active monitor of local disease control authorities (51.4%, 126/245) than in clinics (48.6%, 119/245). 59.6% of the cases seeked for medication at the first time at the local county hospitals and 49.6% of them（59/119）was misdiagnosed. Snail was found in 30 formally endemic counties with a total area of 1 739.0 hm². Conclusion The total 245 cases of imported schistosomiasis have been reported in Zhejiang Province through active monitoring and passive reporting system from 1996 to 2017. The number of cases has decreased since 2005. The main sources of the imported cases are from the uncontrolled or re-emerging areas of schistosomiasis in the country.

Key words: Schistosomiasis, Imported case, Endemic, Epidemiology, Zhejiang Province