ObjectiveTo analyze the monitoring data of schistosomiasis from 2004 to 2021 in Suzhou New District， Jiangsu Province， and to provide evidence for improving schistosomiasis elimination strategies. MethodsFollowing the Opinions on Prevention and Control of Schistosomiasis， Parasitic Diseases and Endemic Diseases in Suzhou and the Technical Plan for Prevention and Control of Schistosomiasis， Parasitic Diseases and Endemic Diseases in Suzhou， the monitoring of schistosomiasis in the population and snail habitats from 2004 to 2021 was conducted. The Mann-Kendall method and Joinpoint regression method were employed to analyze the trend of epidemic indicators （such as seropositive rate， prevalence of snail frames， etc.）. Time series analysis （exponential smoothing model） was conducted to predict snail occurrence. ResultsFrom 2004 to 2021， a total of 73 680 people were serologically tested for schistosomiasis， with a positive rate of 0.084%. The seropositivity rate showed statistically significant differences between different years （χ²=70.73， P<0.05）， but there was no significant trend over time. In addition， 3 053 fecal tests were conducted and no positive result was found. The snail habitats covered an area of 70.11 hm² and showed a decreasing trend （Z=-1.97， P<0.05）. A total of 30 093 frames were surveyed， of which 19.038% contained snails. The difference in the prevalence of snail frames between different years was statistically significant （χ²=7 203.09， P<0.05）， with a decreasing trend in the prevalence of snail frames （Z=-2.05， P<0.05）. A total of 26 296 live snails were seized and density of live snails was 0.874 snails per frame， showing a decreasing trend in the density of live snails （Z=-2.35， P<0.05）. A total of 12 391 snails were dissected and no infected snail was found. The areas treated with molluscicides remained stable at 264.60 hm². An area of 27.77 hm² achieved the goal of snail eradication through environmental modification， with a decreasing trend （Z=-2.44， P<0.05）. It is estimated that the prevalence of snail frames and snail density will remain relatively stable from 2022 to 2026， but the snail habitat area will fluctuate significantly， showing an increasing trend. ConclusionNo indigenous cases of schistosomiasis and no infected snails are reported， indicating the successful consolidation of schistosomiasis prevention and control measures. However， the snail habitat area fluctuates greatly with an increasing trend， suggesting the need for long-term Oncomelania snail monitoring in local areas.

ObjectiveTo genotype Oncomelania hupensis， based on microsatellites， in different snail-bearing environments in Jiaxing City， Zhejiang Province， for population genetics analysis in order to explore the reasons and influencing factors for the existence or proliferation of snails and to provide scientific basis for effective monitoring and control of snails. MethodsA total of 90 snail samples from three populations were collected in Yaobang Village （YB） and Sanxing Village （SX） in Pinghu City， and Yunhe Farm （YH） in Xiuzhou District， all were selected for snail checking in key snail habitats of Jiaxing City in 2022. DNA of the snails was genotyped and analyzed for population genetics using nine microsatellite loci. ResultsA total of 84 alleles were observed， and the mean number of alleles （Na） was 7.889， 5.667， and 3.778 for YB， SX， and YH respectively； the number of effective alleles （NeA） was 4.807， 3.329， and 2.294， respectively； and the coefficients of inbreeding （F_IS） were 0.400， 0.377， and 0.493， respectively. Under the Infinite Allele Model （IAM）， the SX and YH might have a recent bottleneck. The NEstimator and LDNe software calculated effective population sizes （Ne） were above 31.9. AMOVA analysis showed that the variation of snails in the three populations mainly existed among individuals， accounting for 41.4% of the total variation. The value of the index of genetic differentiation between populations （F_ST） was 0.286， indicating a high degree of genetic differentiation. The results of the principal component analysis and phylogenetic tree were consistent， and the three populations were divided into two lineages， YB and SX were one lineage， and YH belonged to another independent lineage. Population history and dynamics analysis showed that the gene flow of the three populations was insufficient， population divergence history indicated that YH might have diverged from SX first， and YB was produced by the contact fusion of SX and YH. ConclusionThe genetic diversity of snail populations in Jiaxing City is generally low， and the snail populations are unstable， with a great degree of genetic differentiation and insufficient gene flow among populations. This study can provide a basis for evaluating the effectiveness of the control of the snail as well as monitoring the trend of the spread of the snail.