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Objective: To understand the Oncomelania hupensis distribution and infection status in the schistosomiasis surveillance sites of Yunnan Province, so as to provide the evidence for making the control and prevention measures., Methods: Eighteen administrative villages were selected as the surveillance sites where the schistosomiasis endemic was serious in 18 epidemic counties, one village for one county. The snail status was investigated with the systematic sampling and environmental sampling methods, and the infection status of the snails was detected by a microscope and loop-mediated isothermal amplification (LAMP). The surveillance database was established and descriptively analyzed., Results: In 2015, the total surveillance area was 1826.55 hm², and the area with snails was 55.03 hm², that was reduced by 57.70% as compared to that in 2013, and by 40.63% as compared to that in 2014. No new snail area was discovered, and also no schistosome infected snails were discovered. Totally 718,532 frames were surveyed, and the occurrence rate of frames with snails was 0.45% and the density of living snails was 0.013 9 snail/0.1 m². In the endemic controlled areas, the snail area and density of living snails were both the highest. The snails concentrated on the environments of paddy field, ditch, bottomland, small reservoir, and dry land, and the vegetations of rice, dry crop, weed and wood. The snail area, occurrence rate of frames with snails, total number of snails and number of living snails all showed a downward trend. No infected snails were found for three years., Conclusions: The Oncomelania hupensis snails have been effectively controlled in the national schistosomiasis surveillance sites of Yunnan Province. However, the comprehensive snail control measures still should be continually strengthened in order to consolidate the achivements.

Objective: To evaluate the current prevalence situation of schistosomiasis in Yunnan Province, so as to provide the evidence for making further control strategy., Methods: The data of schistosomiasis were collected and analyzed statistically in Yunnan Province in 2014., Results: There were 7 transmission controlled counties and 11 interrupted counties in Yunnan Province in 2014, and Oncomelania hupensis snails were not found in 5 of the 11 interrupted counties for at least 5 years. In the transmission controlled areas, the schistosomiasis endemic villages, population, farm cattle, and snail areas accounted for 80.94%, 83.72%, 79.32% and 82.00% of whole schistosomiasis endemic areas in Yunnan Province, respectively. The infection source was not completely eliminated., Conclusion: In the transmission controlled areas, the elimination of infection source should still be strengthened; in the transmission interrupted areas, the import infection sources should be prevented.

Objective: To master the dynamic endemic status and influencing factors of schistosomiasis in Yunnan Province, so as to provide the evidence for making the control and prevention measures., Methods: Four villages of four schistosomiasis heavy endemic counties were selected as survey sites. Then, the serological screening and etiological tests were carried out in the residents, and the basic situations of the survey sites were investigated. The infection status of the livestock and relevant information of Oncomelania hupensis snails were surveyed. All the results were analyzed statistically., Results: Totally 4310 residents were surveyed by the indirect hemagglutination assay with the examination rate of 79.68% and serum positive rate of 8.40%. The positive rate reached upwards 12.53% in Qiandian Village of Eryuan County. The serum positive rate of the female was higher than that of the male, and the positive rates of the 30 years and older age groups were higher than those of the other age groups. The serum positive rates of the peasants, migrant labourers and residents with the junior high school education level were higher. No positive feces were found. A total of 24 advanced cases were reported. No positive livestock and snails were found, and the average density of living snails was 0.023 3-0.056 6/0.1 m2., Conclusion: Right now, the schistosomiasis is at a low prevalence status in Yunnan Province, and the endemic situation has been effectively controlled.

Objective: To understand the condition of the construction and management of sanitary latrines, and assess the effect of disposal of the excrement in rural schistosomiasis endemic areas in Yunnan Province., Methods: Three villages with schistosomiasis endemic were selected from Eryuan County and 30 households per village were sampled randomly for the field survey. The stool samples were sampled and tested according to the national standard., Results: Totally 90 latrines were surveyed. The popularity rates of sanitary latrines in Yongle, Qiandian and Xinzhuang villages were 83.19%, 83.12% and 81.63% respectively. In the 90 household latrines, only 32.22% located inside the courtyard, and 91.67% of sanitary latrines and 70.00% of non-sanitary latrines had integrated buildings. Maggots or pupae or adult flies were found in 33.33% of sanitary latrines and all of non-sanitary latrines with the average amounts of 1.05 and 3.40 per latrine respectively. The removal rate of fecal coliform, the sedimentation rate of parasitic eggs and the mortality rate of Ascaris eggs were 90.00%, 80.61% and 95.20% on average respectively. The qualified rate of the fecal coliform of the outlet of the sanitary latrines was 41.67%, and the qualified rate of the mortality rate of Ascaris eggs was 78.13%. No living schistosome eggs were found at the outlets of latrines. For the effect of non-hazardous treatment, there was a statistically significant difference between the sanitary latrines and non-sanitary latrines., Conclusions: The latrine improvement has a good effect on non-hazardous treatment of the excrement in Yunnan Province, but the construction, application and management of sanitary latrines still need to be strengthened.

Objectives: To evaluate the effect of comprehensive schistosomiasis control project in Yunnan Province after its implementation for ten years, so as to provide the evidence for formulating the future prevention and control strategy., Methods: The data of the schistosomiasis comprehensive control project and the endemic situation were collected and analyzed to evaluate the control effect of the project in Yunnan Province from 2004 to 2013., Results: After the comprehensive control project implementation for ten years, the Oncomelania hupensis snail area in Yunnan Province decreased from 4,364.79 hm2 in 2004 to 1,528.50 hm2 in 2013, with a reduction rate of 64.98%, and the occurrence rate of frames with snails and the density of living snails decreased from 4.71% and 0.26 snails/0.1 m2 in 2004 to 1.35% and 0.04 snails/0.1 m2 in 2013, with the reduction rates of 71.34% and 84.62%, respectively. The schistosome infected snails were found only in 2011 and 2013 since 2008. In 2013, the infection rates of human (0.0021%) and cattle (0.0209%) decreased by 99.84% and 99.44%, respectively, compared to those in 2004, and no acute schistosome infection cases were found since 2008. The 212 villages with relatively serious endemic situation (Type One, Type Two and Type Three) all declined to the slight endemic villages (Type Four and Type Five), therefore, they reached the criteria of schistosomiasis transmission controlled or interrupted. The awareness rates of schistosomiasis control among villagers and students in endemic areas were above 90% and 98%, respectively., Conclusion: The effect of the comprehensive schistosomiasis control project is significant in Yunnan Province, but the task to consolidate and enlarge the control results still remains a challenge.

Objective: To evaluate the molluscicidal effect of 5% powder of niclosamide ethanolamine salt granules (NEG) in the field of mountainous areas in Yunnan Province., Methods: The grasslands with Oncomelania hupensis snail habitats were chosen in Beideng Village, Heqing County, Yunnan Province, and were divided into 7 groups (groups of NEG 30 g/m2, NEG 40 g/m2, NEG 50 g/m2, NEG 40 g/m2 plus obstacle clearing, 50% niclosamide ethanolamine salt wettable powder (WPN) 6 g/m2, WPN 6 g/m2 plus obstacle clearing, and fresh water). The snail death rates and the densities of living snails were investigated and the results were compared in the different groups 7 d, 15 d, and 30 d after the implementation., Results: Seven d, 15 d, and 30 d after the implementation, the snail death rates of the groups of NEG 30 g/m2, 40 g/m2, and 50 g/m2 were from 72.75 % to 95.83%, and the average descent rates of living snail densities were from 72.26% to 95.54%. Seven d, 15 d, and 30 d after the implementation, in the NEG 40 g/m2 group, the snail death rates were from 81.69% to 87.19%, and the average descent rates of living snail densities were from 81.42% to 87.91% ; in the NEG 40 g/m2 plus obstacle clearing group, the snail death rates were from 84.89% to 88.24% and the average descent rates of living snail densities were from 85.63% ~ 88.22%; in the WPN 6 g/m2 group, the snail death rates were from 85.23% to 86.17% and the average descent rates of living snail densities were from 85.76% to 86.05%; in the WPN 6 g/m2 plus obstacle clearing group, the snail death rates were from 88.89% to 92.10% and the average descent rates of living snail densities were from 86.71% to 92.20%. The obstacle clearing improved the molluscicidal effect., Conclusion: NEG has a good molluscicidal effect in the field of mountainous areas in Yunnan Province.

Objective: To establish and perfect the surveillance and forecast system of schistosomiasis, and timely discover the suspicious high risk environments for preventing the human and livestock from schistosomiasis., Methods: Eight villages of three counties were selected as survey points. Then, the surveillance and forecast of sentinel mice were carried out in the key water regions. The recovered sentinel mice were dissected in laboratory. The sentinel mouse serum antibodies against schistosome were detected by ELISA, the suspicious water contacts of residents and livestock were investigated and the results were analyzed, and the epidemic risk was assessed., Results: Totally 300 sentinel mice were placed, the recovery rate was 94.67%, and the mortality rate was 8.80%. There were no mice with positive serum antibodies against schistosome, and the results of the dissection of all the sentinel mice were negative. The humans who contacted with the suspicious water were mainly villagers, students, children and fishermen by washing hands and feet, washing vegetables, harvesting, fishing and swimming. The Oncomelania hupensis snail areas, human infection rates, and cattle infection rates were obviously declined in recent 3 years. However, the epidemic risks still existed., Conclusion: Although schistosomiasis transmission was effectively controlled in the three counties, the comprehensive control measures still should be strengthened.

Objectives: To understand the status of wild feces distribution and pollution in schistosomiasis endemic areas in Yunnan Province., Methods: According to the distribution of Oncomelania hupensis snails and characteristics of human and animal activities in recent five years, 6 schistosomiasis endemic villages in Weishan, Nanjian and Midu counties (2 villages each county) were selected as the investigated areas and. more than 4 hm2 area with snails around each village were investigated for the types and densities of wild feces. The schistosome infested feces was detected with the hatching method., Results: Totally 63 hm2 were investigated and 420 wild feces were found in all kinds of environments. The densities of wild feces were 0.066 7 piles/100 nm2, and the densities of wild feces of the road and the hillside were the highest (0.098 7 piles/100 m2 and 0.088 0 piles/100 m2 respectively). Totally 260 fresh wild feces were collected, including the feces of human being, cattle, horse, dog, sheep and pig, and the feces of cattle and dog was the most (37.38% and 30.71%, respectively). No schistosome positive feces was found., Conclusions: There are a lot of wild feces in snail areas in Yunnan Province, and the risk of schistosomiasis transmission is still high. Therefore, we should strengthen the banning grazing measures and the investigation of dogs.

Objective: To evaluate the effect of schistosomiasis control in Yunnan Province since achieving the transmission control standards, so as to provide the evidence for formulating the next prevention and control strategy., Methods: The schistosomiasis epidemic monitoring reports, annual reports, relevant information about Oncomrnelania hupensis snails, and schistosomiasis patient conditions were collected and analyzed for epidemic condition and characteristics of schistosomiasis in Yunnan Province from 2009 to 2012., Results: The various epidemic monitoring indicators all decreased. In 2012, compared with 2009, the prevalence reduced by 33.33% after correction; the number of villages with schistosomiasis patients reduced by 55.56%; the adjusted positive rate of livestock stool tests reduced by 45.45%; the number of villages with infected cow reduced by 42.25%; the actual area with snails reduced by 13.58%; the density of living snails reduced by 25.66%, and no schistosome infected snails were found in 2012., Conclusion: There still exist schistosome infections in human and animals in some local areas of Yunnan Province, and it is difficult to achieve the standard of schistosomiasis transmission interrupted in a short period.

Objective: To evaluate the effect of a novel plant molluscicide, 4%"Luo-wei" (Tea-seed distilled saponins, TDS) against Oncomelania hupensis snails in plateau mountain areas in Yunnan Province., Methods: The immersing and spraying experiments were carried out in the ditches and grassland of Xiaolian Administrative Village in Heqing County, Yunnan Province, to assess the molluscicidal effect of 4% TDS comparing with 50% wettable powder of niclosamide ethanolamine salt (WPN) in different environments and time., Results: After immersion for 24, 48 h and 72 h, the snail death rates were 70.67%, 87.33% and 98.67% in the TDS group, whereas being 77.33%, 96.67% and 100.00% in the WPN group, respectively. The differences of the death rates between the two groups 24 h and 72 h after immersing were not statistically significant ( chi2(24h) =1.73, chi2(72h) = 2.01, both P values > 0.05). Seven days after the immersing experiments, the occurrence rate of frames with living snails and the death rate of snails were 20.00% and 93.03% in the TDS group, while those were 13.33% and 95.76% in the WPN group, and there were no significant differences of the 2 indexes between the 2 groups ( chi(2)(Occurrence rate) = 2.27, chi(2)(Death rate) = 0.94, all P values > 0.05). After spraying for 1, 3, 7 d and 15 d, in both groups, the occurrence rates of frames with living snails and the average densities of living snails gradually declined, while the death rates of snails gradually increased with the extension of time. There were no statistically significant differences of the above 3 indexes between the 2 groups (all P values > 0.05). Fifteen days after the spraying experiment, the occurrence rate of frames with living snails and the adjusted death rate of snails were 15.00% and 87.39% in the TDS group and those were 16.67% and 89.32% in the WPN group, respectively., Conclusion: The molluscicidal effect of TDS is satisfying in plateau mountain areas, and the molluscicide is worthy of further extension and application.

Objective: To understand the types of schisotsome infection sources and their roles in schistosomiasis transmission in mountainous endemic regions in Yunnan Province, so as to provide the evidence for implementing the comprehensive control measures based on infection source control., Methods: Two villages of typical mountainous regions in Nanjian County were chosen for field investigation. The Oncomelania hupensis snail status was surveyed by the methods of systematic and environmental sampling. The infections of schistosomiasis were surveyed in residents with the indirect haemagglutination and the hatching method, in livestock with the hatching method and in wild animals with the anatomical method and the hatching method. The distribution and pollution status of wild faeces were investigated in the snail environments nearby villages or with livestock frequent activities. The positives of schistosomiasis in wild faeces were tested with the hatching method. The pollution index of wild feces was calculated., Results: A total of 533.56 hm2 were investigated in two villages, and the area with snails was 16.52 hm2. The rate of frame with snails was 1.03%, the average density of snails was 0.07 snails/0.1 m2, and no positive snails were found. The positive rate of blood examinations of population was 1.61%, but no persons were positive with the hatching method. The infection rates were 0.90%, and 0.62% in cattle and equus, respectively, and there were no positives in other livestock. Totally 472 piles of wild feces of 6 species (human, cattle, equus, goat, pig and dog) distributed in the investigation areas, and among them, the densities of wild feces of cattle, equus, and dog were 7.2, 4.3 piles/hm2, and 2.1 piles/hm2 respectively, being relatively higher than others. The hatching positive rates of wild faeces of cattle, equus, and dog were 2.27% (3/132), 2.63% (2/76), and 3.70% (1/27), respectively. The relative pollution indexes of wild faeces of cattle, equus, and dog were 80.68%, 15.89%, and 3.43%, respectively., Conclusions: After schistosomiasis transmission is controlled, the potential epidemic factors still remain in the mountainous endemic regions of schistosomiasis in Yunnan Province. The cattle are still the most infection source of schistosomiasis, but equus and dog as infection sources should be not neglected. We should extend the investigation and monitor scope of the infection sources, and carry out scientific and feasible control technique and management measures.

Objective: To observe the molluscicidal effect of a novel molluscicide, salt of quinoid-2', 5-dichloro-4'-nitrosalicylanilide (LDS) on Oncomelania hupensis in laboratory and field of mountainous areas of Yunnan Province., Methods: With the immersion method, 10% LDS with concentrations of 0.1, 0.2, 0.4, 0.6, 0.8 mg/L was tested, and 50% niclosamide (WPN) with the concentration of 2 mg/L as well as fresh water were tested as the controls. The molluscicidal effects of 24, 48, 72 h were observed in lab and the field. With the insufflation method and powdering method, 10% LDS with doses of 0.2, 0.4, 0.6, 0.8, 1.0 g/m2 was tested and 50% WPN with the dose of 2 g/m2 as well as fresh water were tested as the controls. The molluscicidal effects of 1, 3, 7 d were observed in lab and the field., Results: At the room temperature of 25-26 degrees C and water temperature of 21-22 degrees C, when exposed for 72 h by the immersion method, the snail death rates of above-mentioned five concentrations of LDS and WPN as well as fresh water were 93.33%, 100%, 100%, 100%, 100%, 100% and 6.67%, respectively in lab. At the field temperature of 18-28 degrees C and water temperature of 18-23 degrees C, when exposed for 72 h by the immersion method, the snail death rates of above-mentioned five concentrations of LDS and WPN as well as fresh water were 91.11%,100%,100%, 100%, 100%, 100% and 3.33%, respectively in the field. When exposed for 7 d by the insufflation method, the snail death rates of five above-mentioned dosages of LDS and WPN as well as fresh water were 90.00%, 94.00%, 96.00% 99.00%, 99.00%, 94.00% and 6.00%, respectively in lab and 80.00%, 82.14%, 88.35%, 90.83%, 96.55%, 92.56% and 4.55%, respectively in the field. When exposed for 7 d by the powdering method, the snail death rates were 74.77%, 88.89%, 94.50%, 90.38%, 92.17%, 90.38% and 4.55%, respectively in the field., Conclusion: LDS has a good molluscicidal effect on Oncomelania hupensis in mountainous areas.

Objective: To analyze the changes of schistosomiasis endemic situation before and after reaching the criteria of schistosomiasis transmission control or transmission interruption in endemic rebounded areas, so as to offer the information for modifying the criteria of schistosomiasis control and elimination, and consolidating achievements of schistosomiasis control in People's Republic of China., Methods: Twelve counties with endemic rebound were selected from seven endemic provinces and investigated with the retrospective research method. The data including the epidemic information and relative materials 10 years before the counties reached the criteria of transmission control and several years later (until 2008 or 2009) were collected. The changes of epidemic situation of these counties before and after the transmission was under control or interrupted, and the factors causing the endemic rebound were analyzed., Results: Counties consolidated the endemic situations with an average time of 5 +/- 3 years after the transmission control, with endemic rebound normally caused by single factor. The ratio of Oncomelania snail areas to historically accumulative snail areas increased over 10% in hilly endemic regions and lake endemic regions in 7 and 12 years separately, while it was stabilized in a low level in water-network endemic areas. The rebound peak time of infected snail densities was consistent with or later than that of densities of living snails. The prevalence of schistosome infection in humans in lake endemic regions rebounded 2 years after transmission under control. The transmission interruption counties consolidated the endemic situations with an average time of 7 +/- 4 years. The human prevalence of schistosome infection decreased to a very low level after the counties reaching the criteria of transmission interruption. The snail areas increased to over 2% of historically accumulative snail areas 3-6 years after transmission interruption in lake, water-network endemic areas successively, while densities of living snails and infected snails were increased at the same year or 2-3 years later., Conclusions: The endemic rebound in regions after the transmission under control or interrupted is caused by biological, natural and social factors and mainly presents as the rebound of snail status. The modification of criteria for schistosomiasis control and elimination should consider the influence of variation of snails, snail areas and density of infected snails on endemic situations in different endemic areas comprehensively. Sensitive and valid surveillance and forewarning system should be established to strengthen the monitoring and consolidating endemic situation in endemic areas after the transmission under control or interrupted.

Objective: To summarize and analyze the process of the changes of schistosomiasis infection and Oncomelania snails in schistosomiasis transmission-controlled areas to explore the rules of the impact of changes of snail indexes on human infection before and after the stage of transmission control, so as to provide the evidence for editing snail indexes in the schistosomiasis controlled criterion and a more scientific, standardized control assessment and evaluation., Methods: Twenty-one schistosomiasis transmission-controlled or transmission-interrupted counties in lake endemic areas and hilly endemic areas in 8 provinces were selected and investigated retrospectively to collect schistosomiasis epidemiological information 10 years before these counties reached the criterion of transmission control and the subsequent years until 2008 or 2009. A " Standard county schistosomiasis epidemic survey data review software" was developed to establish a national epidemic retrospectively database; the trends of changes of snail status, infected snail status and human infection status were analyzed in different years. The trends and rules of the changes of snail areas, emerging snail areas, living snail densities, infected snail densities, snail infection rates and human infection rates were analyzed and compared before and after the counties reached the schistosomiasis transmission-controlled criterion in different types of endemic areas., Results: Before the transmission control, the human infection rate presented a declining trend in endemic areas. In lake endemic areas, the human infection rate declined to below 5% 4 years before the transmission control; in hilly endemic areas, the human infection rate declined to below 3% 8 years before the transmission control, and the human infection rates of the lake and hilly endemic areas declined to 2.10% and 1.45%, respectively, at the year of transmission control. However, 3 to 4 years after transmission control, the disease began to rebound, especially in lake endemic areas. The snail areas and snail densities declined year by year 10 years before the transmission control in the lake and hilly endemic areas, and the proportion of snail areas occupying the historic snail areas declined the lowest, being 2.75% and 0.55%, respectively, at the year of transmission control. The average densities of living snails kept a low level from 3-4 years before the transmission control to 9-10 years after the transmission control, and then rebounded. The new snail areas appeared 6-7 years after the transmission control and the snail areas and densities of living snails rebounded 9-12 years after the transmission control., Conclusions: The snail status can maintain a relatively low level during about 10 years after the transmission control in the lake and hilly schistosomiasis endemic areas, but the schistosomiasis status rebounded 5 years after the transmission control. While the comprehensive measures mainly including infectious source controlled are implemented, the snail surveillance and control should be still strengthened, and it is recommended that "the proportion of snail areas decreased" and "the control of infected snails" would be the indicators of the criterion of schistosomiasis transmission control.

Objective: To analyze the changing rules of schistosomiasis endemic situation in the area of transmission that has been interrupted before and after they reach the criteria of transmission interruption, so as to offer the basis of amending to the criteria of schistosomiasis transmission interruption and a more scientific, standardized assessment and evaluation of the effects of schistosomiasis control in the future., Methods: Nineteen counties of transmission that has been interrupted in 9 provinces nationwide were selected and investigated with the retrospective research method to collect and record the endemic detailed data 10 years before they reach the criteria of transmission interruption and several years later (ended in 2008 or 2009) and then a database was established. The changing rules of various disease indices in different endemic areas before and after reaching the criteria of transmission interruption were analyzed and compared., Results: The average time from the transmission control to the transmission interruption was 17 years in the 17 counties. After reaching the criteria of transmission interruption, the infection rates of people turned down to a minimum level in various endemic areas, the infection rates in a few numbers of lake endemic areas and hilly endemic areas increased slightly after the transmission interruption 4-9 years later, but all of them were below 1%. The densities of living Oncomelania snails in lake endemic areas and water-network endemic areas were high and the changes were great each year, and the densities of living snails were much lower in hilly endemic areas than in the above two types of areas and they came to the lowest 4 years before and after the transmission interruption. The infected snails appeared occasionally in lake endemic areas, and they recurred 6 years and 10 years after the transmission interruption in water-network endemic areas and hilly endemic areas, respectively. The continued time without infected snails found before reaching transmission interruption was 2.71 +/- 1.10 years averagely in transmission-interrupted counties with endemic stable, and was 3. 80 +/- 1.43 years in lake endemic areas., Conclusions: It is possible to maintain a low level of population schistosome infection, and the endemic rebound is shown as snail rebound after the endemic areas reach the criteria of transmission interruption, The infected snails could be the comprehensive index reflecting the control achievement and the risk of schistosomiasis transmission. So the persistent control of infected snails is the fundament of schistosomiasis transmission interruption. It is suggested that in our current social and economic development and science and technology capacity conditions, the status of no infected snails found continuously for 5 years would be one of the criteria of schistosomiasis transmission interruption.