RESUMO
Objective To establish a surveillance and early warning index system for schistosomiasis transmission risk along the middle and lower reaches of the Yangtze River basin, so as to provide insights into creation of a sensitive and highly efficient surveillance and early warning system for schistosomiasis. Methods National and international publications, documents, laws and regulations pertaining to schistosomiasis control were retrieved with keywords including schistosomiasis, surveillance, early warning and control interventions from 2008 to 2022, and a thematic panel discussion was held to preliminarily construct surveillance and early warning index system for schistosomiasis transmission risk along the middle and lower reaches of the Yangtze River basin. The index system was then comprehensively scored and screened using the Delphi method, and the weight of each index was determined using analytic hierarchy process and the modified proportional allocation method. In addition, the credibility of the Delphi method was evaluated using positive coefficient, authority coefficient, degree of concentration and degree of coordination of experts. Results Following two rounds of expert consultation, a surveillance and early warning index system for schistosomiasis transmission risk in endemic areas along the middle and lower reaches of the Yangtze River basin was preliminarily constructed, including 3 primary indicators, 9 secondary indicators and 41 tertiary indicators. The normalized weights of primary indicators epidemics, natural and social factors and comprehensive control were 0.639 8, 0.145 6 and 0.214 6, respectively, and among all secondary indicators, snail status (0.321 3) and schistosomiasis prevalence (0.318 5) had the highest combined weights, while social factors had the lowest combined weight (0.030 4). Of all tertiary indicators, human egg-positive rate (0.041 9), number of acute schistosomiasis cases (0.041 5), number of stool-positive bovine and sheep (0.041 1), and prevalence of Schistosoma japonicum in free-ranging livestock (0.041 1) had the highest combined weights. During two rounds of consultation, the positive coefficient of experts was both 100%, and the authority coefficient was both 0.9 and greater, while the coordination coefficients were 0.338 to 0.441 and 0.426 to 0.565 (χ2 = 22.875 to 216.524, both P values < 0.05). Conclusions The established surveillance and early warning index system for schistosomiasis transmission risk along the middle and lower reaches of the Yangtze River basin is of great scientific values and authority, which may provide insights into construction of the sensitive and highly efficient surveillance and early warning system for schistosomiasis in the context of low prevalence and low intensity of infection in China.
RESUMO
@#Abstract: Objective To analyze the emergency response and long-term intervention effects after the detection of infectious snails epidemic by loop-mediated isothermal amplification (LAMP) assays in Hannan District, Wuhan City, and to explore the application of LAMP in early surveillance and early-warning of schistosomiasis transmission. Methods Snails picked up by the risk monitoring system in Hannan District were examined by anatomical microscopy and LAMP technology to identify the schistosomiasis infection. Emergency response and intensive intervention were initiated in the environment where positive snails appeared, and the long-term effects were evaluated. Results In May 2018, the infectious snails were detected by LAMP technology in Hannan District, and the positive snails were located in Zhujiacha, Dongzhuang Village, Obstacles and weeds were removed and buried by machine in Zhujiacha. 12 700 m2 of snails were killed by drugs, and the mortality rate of snails was more than 80%; no new seropositive persons were found in the emergency examination within 500 m of the positive snail sites. 506 people were examined in Dong Zhuang Village at the end of the year, and 30 positive IHA cases were detected with a blood positive rate of 5.93%, no positive fecal test was found, and all positive blood test patients took preventive medication. The monitoring results of sentinel rats and wild feces were all negative. Health education was carried out, 7 warning signs were deployed and refreshed, and 500 publicity brochures were distributed. After nearly three years of intensified intervention and monitoring in the villages where the positive environment is located, and the density of snails on the stubborn snail has dropped from 0.094/frame to 0.027/frame, and the positive rate of blood test in Dongzhuang Village has steadily dropped from 5.93% to 3.74%. Conclusions The infected snails missed by microscopy were detected by LAMP in Hannan District, which created conditions for the rapid emergency treatment of environment and elimination of positive snail and improved the sensitivity of the surveillance and early warning system in transmission-interrupted areas.