Objective To understand the Oncomelania hupensis distribution and infection status in the schistosomiasis sur?veillance 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 epi?demic 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 amplifica?tion(LAMP). The surveillance database was established and descriptively analyzed. Results In 2015,the total surveillance ar?ea was 1 826.55 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 liv?ing 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 com?prehensive snail control measures still should be continually strengthened in order to consolidate the achivements.

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 schistoso-miasis epidemic monitoring reports,annual reports,relevant information about Oncomelania 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 preva-lence 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 Prov-ince,and it is difficult to achieve the standard of schistosomiasis transmission interrupted in a short period.

Objective To carry out the surveillance with sentinel mice in the key water areas of schistosomiasis endemic re-gions in Yunnan Province,so as to establish and perfect the surveillance and forecast system of schistosomiasis. Methods Six villages of three counties with schistosomiasis heavy endemic status were selected as the survey points. Then ,the surveillance and forecast with the sentinel mice were carried out in the key water areas in the survey points. The recovered sentinel mice were dissected in laboratory,and their serum antibodies against schistosome were detected. Meanwhile,the suspicious infested water contacts of the residents and livestock in the surveillance sites were investigated,and the endemic data of schistosomiasis in the survey points in recent 3 years were collected and analyzed. Results Totally 282 sentinel mice were placed in the water area, 252 were recovered,with a recovery rate of 90.78%,and 8 mice were dead,with a mortality rate of 3.13%. The number of mice with schistosome egg granuloma and adult worm detected were both 0,and the worm burden and the positive rate of serum anti-bodies against schistosome were both 0,too. The persons who contacted with the suspicious infested water were mainly villagers and students by harvesting and playing. The Oncomelania hupensis snail areas,the infection rates of residents and livestock were obviously declined in recent 3 years. Conclusions There are no positive sentinel mice found in the key water areas of the surveillance sites in Yunnan Province,which suggests that the schistosome infection risk of residents and livestock is low. How-ever,the comprehensive control measures,surveillance and forecast with sentinel mice in the key water areas of schistosomiasis endemic regions still should be strengthened.

Objective To evaluate and compare the short-term effects of two kinds of plastic mulch on Oncomelania hupensis snail control in irrigation and drainage ditches with snails in Yunnan Province. Methods The irrigation and drainage ditches with high density of Oncomelania hupensis snails were chosen as the investigation sites,and then 4 groups were set,namely a colorless plastic mulch group,black plastic mulch group,colorless plastic mulch with molluscicide group and black plastic mulch with molluscicide group. The snail situation of the 4 groups was surveyed before the experiment and 7,14,21,30 days after covering plastic mulch,and the snail death rates were compared among the 4 groups. Meanwhile,the hourly temperatures of soil surface,soil surface under plastic mulch and soil layer 5,15 cm under the surface as well as the weather situation during the study period were measured and recorded. Results The average snail mortality rate of the colorless plastic mulch group was only 15.29% that was higher than that of the black plastic mulch group(6.56%)(P < 0.01). The average snail mortality rates of the colorless and black plastic mulch with molluscicide groups were 40.80% and 50.15%,respectively,and there was no statis-tic difference between them(P > 0.05). Both kinds of plastic mulches could raise the temperature of the soil surface under plas-tic mulch and the soil layer below it,and the temperature of soil under the mulches increased over the cover time,and the aver-age temperature of the soil surface under the black mulch in 30 days was higher than that under the colorless mulch. Conclu-sion It is not suitable to use plastic mulch only in irrigation and drainage ditches with snails widely in Yunnan Province be-cause of its low effect,and if necessary,the molluscicide should be added.

Schistosomiasis was once hyper-endemic in Yunnan Province. Following concerted efforts for over 70 years, remarkable achievements have been made for schistosomiasis control in the province. In 2004, the Mid- and Long-term Plan for Schistosomiasis Prevention and Control in Yunnan Province was initiated in Yunnan Province, and the target for transmission control of schistosomiasis was achieved in the province in 2009. Following the subsequent implementation of the Outline for Key Projects in Integrated Schistosomiasis Control Program (2009—2015) and the 13th Five - year Plan for Schistosomiasis Control in Yunnan Province, no acute schistosomiasis had been identified in Yunnan Province for successive 12 years, and no local Schistosoma japonicum infections had been detected in humans, animals or Oncomelania hupensis snails for successive 6 years in the province by the end of 2020. The transmission of schistosomiasis was interrupted in Yunnan Province in 2020. This review summarizes the history of schistosomiasis, changes in schistosomiasis prevalence and progress of schistosomiasis control in Yunnan Province, and proposes the future priorities for schistosomiasis control in the province.