[Trend analysis of schistosomiasis endemic situation in Anhui Province from 2004 to 2014].

OBJECTIVE: To analyze the changes of schistosomiasis endemic situation in Anui Province from 2004 to 2014, so as to provide the evidence for formulating "The thirteenth five year" schistosomiasis control plan. METHODS: The information for schistosomiasis control and the data of the endemic surveillance of schistosomiasis were collected and analyzed for the changes of schistosomiasis endemic situation in Anhui Province from 2004 to 2014. RESULTS: The Oncomelania hupensis snail areas presented on a rising trend, and reached to the largest area with about 3.1 billon m2in 2011. However, the snail areas decreased from 2012, and reduced by 10.55% in 2012 compared with the areas in 2011, and reduced to the lowest level in 2014 in recent 10 years. The density of living snails presented a fluctuation situation from 2004 to 2008, and on a decreasing trend from 2008, and the density of living snails was below 1 snail/0.l i2 after 2011. The infection rate of snails remained stagnant state from 2004 to 2011, and decreased rapidly in 2012, and no schistosome infected snails were found in 2013 and 2014. The schistosome infection rate of residents decreased gradually, and the number of acute schistosomiasis was under 50 cases with scattered distribution after 2006, and no acute cases occurred in 2013 and 2014. The infection rate of livestock was above 1% from 2004 to 2011, and reduced to 0.55% in 2012, and it was the first time that the infection rate of livestock was lower than that of residents in the same year in 2014. The progress for achieving the goal of schistosomiasis transmission control accelerated after 2011, and the number of counties that reached the standard of schistosomiasis transmission controlled from 2012 to 2014 was 4, 9 and 14 and the number of townships was 33, 76 and 32, respectively. CONCLUSION: Schistosomiasis control has achieved remarkable effectiveness in Anhui Province, but there still exists hard work to consolidate the achievement and reach schistosomiasis transmission interrupted.

[Investigation on endemic situation of schistosomiasis in infection-controlled regions in Anhui Province].

OBJECTIVE: To understand the epidemic situation of schistosomiasis in 27 counties (cities, districts) that reached the criteria of schistosomiasis infection controlled in Anhui Province. METHODS: According to the requirement of The National Assessment Scheme of Schistosomiasis, 81 administrative villages where the schistosomiasis epidemic situation was relatively heaver in above-mentioned 27 counties (1 village per town, 3 towns per county) were sampled and investigated. RESULTS: From 2012 to 2014, 81 villages were investigated, and 34,293 residents received the serum examinations, and 1,086 were positive with a positive rate of 3.17% (0.65%-9.58%), and the positives received stool examinations and the average stool positive rate was 0.37% (0-4.0%). The calculated prevalence of human infection was 0.01%. A total of 3 057 domestic animals were investigated including 438 cattle, 2,550 sheep, and 69 other animals, and no infections were detected. A total of 11,261 living Oncomelania hupensis snails were collected and detected, but no schistosome infected snails were found. Before this investigation, no infected snails were detected for more than 2 years [average 2.3 (2-6) years], and no acute schistosome infection cases were found for more than 2 years [average 4.9 (2-9) years]. CONCLUSION: The infection rates of schistosomiasis in residents and domestic animals are relatively low, and no schistosome infected snails are found in the regions.

[Application of space-time scan statistics in early warning of distribution of schistosome infected Oncomelania hupensis snails].

OBJECTIVE: To explore the application of space-time scan statistics in the early warning of distribution of schistosome infected Oncomelania hupensis snails. METHODS: The data of distribution of infected snails in Anhui Province from 2006 to 2012 were collected, and a spatial database was established by ArcGIS 9.3. The prospective spatial-temporal cluster analysis was done by SaTscan 9.1.1 at the village level. RESULTS: Four space-time clusters, which were distributed over the Yangtze River and its branch rivers, were detected. CONCLUSION: The space-time scan statistics could detect the distribution of infected snails early, and the space-time clusters found were the key and difficult points of schistosomiasis control in Anhui Province.

[Spatial-temporal analysis on the distribution of infected snail at the village level in Anhui province, 2006-2012].

OBJECTIVE: The characteristics of spatial-temporal distribution on infected snails were analyzed at the village level in Anhui province, 2006-2012. METHODS: Data on the distribution of infected snails from 2006 to 2012 in Anhui province was collected. Spatial database was established by ArcGIS 9.3. Retrospective spatial-temporal cluster analysis was done by SaTScan 9.1.1 at the village level. RESULTS: Eight areas with increased risk and distributed along the upstream to downstream of Yangtze and connecting branch rivers, were found having infected snails, from 2006 through 2012, including one area in 2006, five in 2006-2008, one in 2007-2009 and one in 2009-2011, respectively. Proportion on the number of areas with infected snails decreased from 6.2% in 2006 to 0.5% in 2012. CONCLUSION: The spatial-temporal distribution of infected snail was not random but there appeared significant clusters. The trend seemed to be declining in Anhui province, between 2006 and 2012. Areas being detected as snails positive were important for the schistosomiasis control program to be carried out in Anhui province.

[Burden of disease in Schistosomiasis japonica. IV. Community socioeconomic determinants of chronic schistosomiasis].

OBJECTIVE: To explore the socioeconomic determinants of chronic schistosomiasis japonica at a community (village) level. METHODS: The socioeconomic and epidemiological data (Years lived with disability, YLDs) came from the thematic research carried out in two schistosome-endemic counties, Dangtu and Hanshou, in lake areas between 2004 and 2005. A concentration index was calculated and used to assess the health inequalities between socioeconomic statuses. The community risk factors relating to chronic schistosomiasis were explored by the multiple regression model. RESULTS: The concentration index was -0.12 of Dangtu County and 0.03 of Hanshou County which indicated that there were no health inequalities due to schistosomiasis between communities with different socioeconomic statuses. There was no linear relationship between the economic levels and YLDs of chronic schistosomiasis. The results of multiple regression model showed that the distance from village to schistosome-infested water (P < 0.01) and wet land area per capita (P < 0.05) were significantly related to YLDs of chronic schistosomiasis. CONCLUSION: There is non-linear relationship between socioeconomic levels and YLDs of chronic schistosomiasis, but the distance from village to schistosome-infested water and wet land area per capita are significantly related to the latter.

[Evaluation on the effect of comprehensive control strategy of schistosomiasis with emphasis on infection source control in Anhui province].

OBJECTIVE: To evaluate the effect of comprehensive control strategy of schistosomiasis with emphasis on infection source control in Anhui province. METHODS: Forty endemic villages in Guichi district, Chizhou city, Anhui province were selected as national pilot villages in the years from 2006 to 2008, and another 10 provincial pilot villages were respectively selected from 10 highly endemic villages in 7 cities in 2007. The comprehensive infection source control measures, including "replace cattle with machines", "raise livestock in pens", "improve the sanitary toilets", "supply safe water " and so on were carried out among the above pilot villages. At the end of 2008, 13 national pilot villages and 6 provincial pilot villages were selected to investigate the popularity of schistosomiasis, and the effect of the comprehensive control strategy in those villages were compared. RESULTS: After implementing the comprehensive control strategy, the infectious rate of schistosomiasis in national pilot villages decreased from 4.57% (487/10 659) to 1.76% (147/8370), with the reduction rate at 61.49%, whose difference showed statistical significance (χ(2) = 115.16, P < 0.01); and the density of infected snails decreased from 0.0067/0.1 m(2) to 0.0008/0.1 m(2), the infectious rate of snails decreased from 0.28% to 0.04%, whose reduction rates were 88.06% and 85.71% respectively. While as to the provincial pilot villages, the infectious rate of schistosomiasis decreased from 1.27% (54/4254) to 0.21% (14/6592), with the reduction rate at 83.46%, whose difference showed statistical significance (χ(2) = 94.57, P < 0.01); and the density of infected snails decreased from 0.0025/0.1 m(2) to 0.0003/0.1 m(2), the infection rate of snails decreased from 0.13% to 0.05%, whose reduction rates were 88.00% and 61.54% respectively. CONCLUSION: The comprehensive control strategy with emphasis on infection source control implemented in marshland and lake regions can effectively control the transmission of schistosomiasis.

[Burden of disease in schistosomiasis japonica. I. Calculation and evaluation of years lived with disability of chronic schistosomiasis].

OBJECTIVE: To discuss the evaluation index of the disease burden of chronic schistosomiasis and its calculation methods. METHODS: The epidemiological data came from the thematic research carried out in two schistosome-endemic counties in lake areas between 2004 and 2005. The specific prevalence rates by age group, gender and endemic type were calculated. According to the age-specific disability weight obtained in the thematic research, the years lived with disability (YLDs) and the rates of YLD of stratified samples by age and gender, and the total YLDs of the two counties were calculated. RESULTS: The total YLDs were 1 056.26 and 3 967.43 person-years in Dangtu and Hanshou counties, respectively. The contributing rate of Grade I type village to the total YLDs of two counties was 37.95% (40.08% in Dangtu and 37.39% in Hanshou). For different stratums by age and gender, the older ones and male tended to have larger YLDs. Compared to the non-endemic areas, chronic schistosomiasis brought an average extra of 4.398 and 1.505 years per 1 000 person to population in Dangtu and Hanshou counties, respectively. CONCLUSION: The evaluation to YLDs of chronic schistosomiasis is helpful for prioritizing intervention areas and population, as well as providing a new index for the evaluation of effectiveness of control measures.

[Evaluation of mid-term effectiveness of medium-and-long-term programme for prevention and control of schistosomiasis in Anhui Province].

OBJECTIVE: To evaluate the mid-term effectiveness of the medium-and-long-term programme for prevention and control of schistosomiasis in Anhui Province. METHODS: In the programme, the comprehensive measures were carried out, including the schistosomiasis detection and chemotherapy for residents and livestock, snail control, health education, and infectious source control. The mid-term effectiveness of the programme was observed and evaluated longitudinally. RESULTS: From 2004 to 2009, 750 798 schistosomiasis patients and 547 069 persons with the history of infested water contacting were treated. The number of positive cattle treated was 8 462 cattle-times and the number of cattle with history of infested water contact treated was 117 023 cattle-times. The area with snails control by molluscicides was 30 532.0 hm2, and the area with snails control by environmental modification was 13 979.5 hm2. The number of persons who received health education was 31.73 million person-times. The infectious source control measures were carried out in 40% of endemic villages with human infection rate being more than 1%. Up to 2009, the infection rates of population and cattle, and the incidence rate of acute schistosomiasis reduced to 0.51%, 1.25% and 0.30/100 000, respectively. During the period of 2004-2009, the areas with snails fluctuated from 29 065.4 to 29 740.3 hm2. The densities of living snails and infected snails both showed a declining trend in general. During these years, the whole province reached the criteria of infection control, 4 counties reached the criteria of transmission control, and 4 counties reached the criteria of transmission interruption. CONCLUSION: The effect of the comprehensive strategy of schistosomiasis control is remarkable.

[Spatial analysis of distribution of schistosomiasis in Anhui Province].

OBJECTIVE: To study the distribution of schistosomiasis in Anhui Province based on geographic information system (GIS). METHODS: The survey data of disease and Oncomelania snails in Anhui Province in 2006 were collected, GIS databases were set up, and the inverse distance weighted interpolation method (IDW) based on ArcGIS 9.3 was used to analyze the spatial distribution of schistosomiasis across the province. RESULTS: The simulated maps of distribution of human prevalence and positive rate of serological tests were imitated by using IDW. The region with heavier infection rates of schistosomiasis was distributed over the region of the Yangtze River in Anhui Province, and the endemic areas were joined into a patch in the upper and middle reaches and distributed in pieces in the lower reaches. While the endemic areas were compared with the distribution of infected snails, the IDW map of positive rate of serological tests was more exactly than that of the human prevalence. CONCLUSIONS: The IDW method is helpful to show the distribution of schistosomiasis. The positive rate of serological tests is more sensitive to reflect the current endemic situation of schistosomiasis in Anhui Province.

[Effect of project of afforestation for schistosomiasis prevention on snail control in marshland and lake regions].

OBJECTIVE: To evaluate the effect of the project of afforestation for schistosomiasis prevention on Oncomelania hupensis control. METHODS: The situation of afforestation for schistosomiasis prevention in the field and the snail distribution in marshland regions were surveyed with the systematic sampling method in the spring, 2009. The database of snail distribution was established and the status of afforestation was investigated, and the effect of the project on snail control was evaluated. RESULTS: The rates of frames with living snails in the environment with plantations and the environment without a plantation were 14.9% and 19.7%, respectively, and there was a significant difference (Chi2 = 2 267, P < 0.01). The rate of frames with living snails in agroforestry model was lower than that in other models except for fishery-husbandry-forestry model. The average densities of living snails in the environment with plantations and the environment without a plantation were 0.552 snails/0.1 m2 and 0. 989 snails/0.1 m2, respectively. The average densities of living snails in the cultivating group and un-cultivating group were 0.354 snails/0.1 m2 and 0.653 snails/0.1 m2, respectively. The rate of frames with living snails and the average density of living snails were the lowest in the environment of long-term afforestation. CONCLUSIONS: The project of afforestation for schistosomiasis prevention has a good effect on snail control in Anhui Province. Long-term afforestation could stably maintain the effect on snail control.

[Burden of disease in schistosomiasis japonica. II. Measurement of health inequalities due to chronic schistosomiasis].

OBJECTIVE: To measure and evaluate the health inequalities due to chronic schistosomiasis japonica. METHODS: Based on years lived with disability (YLD) caused by chronic schistosomiasis, a concentration index and Gini index, along with a concentration curve and Lorenz curve, the health inequalities between sexes, age groups or endemicities were identified and quantified. RESULTS: The age concentration index was 0.395 of females and 0.380 of males, with no significant difference between them. More than 60% of YLD was contributed by those aged > or = 45 years old who accounted for about a third of total population in both sexes. Gini index was 0.666 of Dangtu County and 0.451 of Hanshou County, and 60% of YLD was contributed by the highly endemic villages. CONCLUSIONS: The concentration index and Gini index could quantify the magnitude of health inequalities well. The priority of morbidity control should be given to those aged > or = 45 years old and living in highly endemic villages.

[Burden of disease in schistosomiasis japonica III household socioeconomic determinants of chronic schistosomiasis].

OBJECTIVE: To explore the socioeconomic determinants of chronic schistosomiasis japonica at household level. METHODS: The socioeconomic status of case and control families in lake and marsh schistosomiasis endemic areas were investigated by questionnaire, socioeconomic factors were analyzed by the principle components analysis, and the wealth index were calculated to evaluate the economic status at household level. Then the relation between schistosome infection and some influencing factors were analyzed by two-level Logistic regression model. RESULTS: A total of 2 716 households in 91 villages were investigated, among which 1 050 were case families and 1 666 were control families. The values of the first eigenvector of stone/brick house, house with > or = 2 floors, black/white TV, colour TV, washing machine, refrigerator, side occupation were -0.42, 0.46, -0.45, 0.46, 0.32, 0.24 and 0.16, respectively, which suggested that the first eigenvector was the comprehensive index reflecting family wealth. The results of Logistic regression model showed that there were 4 household factors significantly relating to chronic schistosomiasis, namely, the distance from residence to schistosome-infested water, source of washing water, economic status, and wet land area per capita, among which the factor that the distance from residence to schistosome - infested water < 100 m with the highest (OR = 12.590, P = 0). CONCLUSION: In the lake and marsh endemic areas, health education and other intervention to the poor family living along river or lake without safe water supply should be strengthened to control schistosomiasis.

Transmission of Schistosoma japonicum by humans and domestic animals in the Yangtze River valley, Anhui province, China.

The aim of the present work was to assess the relative contribution to transmission of Schistosoma japonicum by humans and domestic animals in two villages in the Yangtze River valley in Anhui province, China. A cross-sectional survey was conducted to determine the prevalence and intensity of S. japonicum in humans, cattle, water buffaloes, horses, pigs, goats, dogs and cats. Additionally, for each host species the number of individuals and the mean faecal excretion per day was determined. Results showed that both prevalence and intensity of infection varied significantly between species and between the two villages and neither of the variables gave an adequate picture of the potential transmission. Total daily egg excretion was significantly higher in Chenqiao village compared with Guanghui village. Whereas humans were the main contributors to transmission of schistosomiasis in Guanghui village (80.4%), water buffaloes accounted for nearly 90% and goats for more than 5% of the transmission in Chenqiao village. Hence, the present study suggests that schistosomiasis transmission might vary significantly within Chinese farm districts and successful control should rely on prior transmission index determinations on major potential contributors rather than routine data of prevalence and intensity of infection. Further studies should determine the value of adding other transmission variables like egg hatchability and faecal deposition habits.