Search

Anhui Province has been one of typical epidemic areas of schistosomiasis in East China as a wide range of large lake and marshland regions provide an ideal environment for growth and reproduction of the intermediate snail host. With the completion of the Yangtze River-Huaihe River Water Transfer Project (YHWTP), launched by the end of 2016, the epidemic areas are expected to expand and controlling schistosomiasis remains a challenge. Based on annual surveillance data at the county level in Anhui for the period 2006-2015, spatial and temporal cluster analyses were conducted to assess the pattern of risk through spatial (Local Moran's I and flexible scan statistic) and space-time scan statistic (Kulldorff). It was found that schistosomiasis sero-prevalence was dramatically reduced and maintained at a low level. Cluster results showed that spatial extent of schistosomiasis contracted, but snail distribution remained geographically stable across the study area. Clusters, both for schistosomiasis and snail presence, were common along the Yangtze River. Considering the effect of the ongoing YHWTP on the potential spread of schistosomiasis, Zongyang County and Anqing, which will be transected by the new water-transfer route, should be given a priority for strengthened surveillance and control. Attention should also be paid to Guichi since it is close to one of the planned inlets of the YHWTP.

Schistosomiasis japonica, caused by Schistosoma japonicum infection, remains a major public health concern in China, and the geographical distribution of this neglected tropical disease is limited to regions where Oncomelania hupensis, the intermediate host of the causative parasite, is detected. The purpose of this study was to monitor the transmission of S. japonicum in potential risk regions of China during the period from 2008 through 2012. To monitor the transmission, 10 fixed surveillance sites and 30 mobile sentinel sites were selected in 10 counties of four provinces, namely Anhui, Jiangsu, Chongqing and Hubei. There were 8, 9, 6, 2 and 3 cases infected with S. japonicum detected in the 30 mobile sentinel sites during the 5-year study period, while 27 subjects were positive for the antibody-based serum test in the 10 fixed sentinel sites; however, no infection was found. In addition, neither local nor imported livestock were found to be infected. No O. hupensis snails were detected in either the fixed surveillance or the mobile sentinel sites; however, the snail host was found to survive and reproduce at Chaohu Lake, inferring the potential of transmission of the disease. It is suggested that the continuous surveillance of schistosomiasis japonica should be carried out in both the endemic foci and potential risk regions of China, and an active, sensitive system to respond the potential risk of transmission seems justified.

To explore the risk factors of cerebral schistosomiasis japonica.A total of 37 confirmed cases, diagnosed during 1999-2004 in Anhui Province, were involved in the study as case group. Three controls for each case were selected from the general population either without schistosomiasis, with chronic schistosomiasis or with acute schistosomiasis. The relevant risk factors on the disease were analyzed.Four factors with labour intensity, physical, economical and nutritional conditions before illness between case group and normal control group, 7 factors including epilepsy history, hypersensitivity, intensity and times of infection between case group and acute schistosomiasis control group, 10 factors including intensity of infection, times of infection and treatment between case group and chronic schistosomiasis control group, all showed statistical significance (p0.05) . Five factors showed statistical significance (p0.05) between case group and the 3 control groups.The intensity of schistosome infection and treatment history are the main risk factors for cerebral schistosomiasis, and the physical and psychosocial conditions of the patients show some effect on the disease.

Schistosomiasis japonica was endemic in 12 provinces (including municipalities and autonomous regions) in the People's Republic of China (PR China). Despite the tremendous decrease of schistosomiasis incidence after almost 60 years of control, the distribution of snail-breeding sites has not been reduced significantly. In order to verify current transmission risks and identify the potential establishment of new foci of schistosomiasis driven by environmental changes, we conducted surveillance in selected risk areas of three provinces: Jiangsu, Anhui and Shandong from 2008 to 2010 in addition to routine snail surveillance. We investigated populations and possible reservoirs in sentinel sites and report that the total number of new acute cases did not diminish further in spite of ongoing control activities. In Anhui Province the local count compared to the national count was 43% (19/44) in 2008, 33% (25/75) in 2009 and 40% (17/42) in 2010. In all, 31.58 km(2) areas of snail breeding sites were newly detected nationwide through the year 2008-2010, of which the proportion of Anhui was 42% (5.03/11.98) in 2008, 95% (8.39/8.79) in 2009 and 79% (8.52/10.81) in 2010. Sentinel surveillance showed eight, nine and five confirmed cases of acute schistosomiasis in mobile populations (fishermen, migrant workers) in 2008, 2009 and 2010, respectively. All these cases were detected in Chaohu County, which must therefore be deemed an area at risk. We conclude that continuous surveillance with an emphasis on snails must be enhanced in potential risk areas in PR China.

To analyze the impact of large hydraulic projects on schistosomiasis transmission and evaluate the transmission risk in potential endemic areas.During 2008-2010, surveillance on risk factors related to schistosomiasis transmission and risk assessment were carried out in potential endemic sites in counties of Xuyu, Hongze, Jinhu, and Gaoyou in Jiangsu Province, Weishan County in Shangdong, Qianjiang City and Yiling District of Yichang City in Hubei, Juchao District of Chaohu City in Anhui Province, Wanzhou and Kaixian in Chongqing in Three Gorges Dam region or passed by South-to-North Water Diversion Project and Zhangjiagang City in Jiangsu Province located in lower reach of Yangtze River. At least one fixed and three temporary monitoring sites were set in each county (city or district). Local inhabitants aged 6-65 years old were screened by indirect haemagglutination assay (IHA) or ELISA, and the sero-positives were tested by Kato-Katz or miracidium hatching techniques to investigate possible infection in 2008. The endemic status of schistosomiasis in mobile population was surveyed every year during 2008-2010. Infection status in livestocks was surveyed in Juchao, Qianjiang, Gaoyou and Wanzhou Counties in 2008-2010. Oncomelania hupensis distribution was investigated in risky and suspicious areas. Snail spreading investigation was conducted through salvaging floater and snails-inducing by straw curtains in rivers connected with Yangtze River.8 256 local inhabitants were investigated by serological tests with a positive rate of 0.7% (60/8 256). Among the 60 serologically positive subjects, 55 individuals were examined by stool examination but none of them was egg positive. The antibody prevalence rate of migrating population in 2008-2010 was 2.0%, 1.4%, and 1.7%, respectively, with no significant difference (chi2 = 3.57, P0.05). Among the serologically positive subjects, egg-positive cases were found in migrating population in Juchao District each year and one case was found in Jinhu County in 2010. Oncomelania snails were only found in in Jinhu and Gaoyou without infected ones. A lot of aquatic shell-fish and snails were collected in the water floater and straw curtain without Oncomelania snails.Schistosomiasis is not endemic in the original nonendemic areas in Three Gorges Dam region and areas passed by South-to-North Water Diversion Project until now, but potential risk of transmission exists. Long term surveillance scheme on schistosomiasis should be established with varied monitoring factors in different category areas.

To understand the dynamic changes of the potential prevalent factors of schistosomiasis in Chaohu Lake area so as to provide forecast information on the outbreak of schistosomiasis in the area.From 2008 to 2010, fixed and mobile surveillance sites in potential endemic areas of Juchao District in Chaohu City, which was located in the southeast side of Chaohu Lake, were selected, and the schistosomiasis infection situation of local people, mobile population and livestock were investigated by immunological assays and/or stool examinations. The distribution of Oncomelania snails was surveyed in risk areas and suspicious areas, the spreading patterns of Oncomelania snails were observed in rivers that directly connected with the Yangtze River, and the Oncomelania snails were raised in the cages on the beaches of Chaohu Lake and a control area, and their survival and reproduction capacity was observed.In 2008, a total of 301 local people were screened by IHA, and there were no positives. From 2008 to 2010, a total of 321, 362 and 306 mobile population were examined by IHA, respectively, and the positive rate of antibody were 3.74%, 4.97% and 2.94%, respectively. The antibody positives were tested by stool examinations, and the positive rates were 66.67%, 50% and 55.56%, respectively. A total of 91 local livestock and 92 livestock from endemic areas were examined respectively by the miracidium hatching method, and there were no positives. A total of 97.8 hm2 risk areas and 193.62 hm2 suspicious areas in the potential endemic area were surveyed respectively, but no Oncomelania snails were found. The investigation results on snail spreading patterns indicated that snails could spread into Chaohu Lake by adsorbing on floating debris. The field study revealed that Oncomelania snails could survive and reproduce in the Lake.The imported infectious sources of schistosomiasis have been found in Chaohu Lake area, and the higher possibility of imported Oncomelania snails spreading into the Lake and surviving and reproducing in the lake is predicted. Therefore, effective measures should be taken to decrease the risks of schistosomiasis transmission in the potential endemic area.