Hupensis Snails Research Articles

Analysis of schistosomiasis endemic status of national surveillance sites in Yunnan Province, 2016

To master the prevalence status of schistosomiasis in Yunnan Province in 2016, so as to provide the evidence for formulating the control strategy and intervention measures. The schistosomiasis heavy-endemic villages were selected from each of 18 endemic counties as the survey sites. Then, the serological and etiological tests were carried out in the local residents and floating population, and the infection status of the livestock, field feces and Oncomelania hupensis snails were surveyed. The serum positive rate of schistosomiasis of local residents was 8.78% and the serum positive rate was 2.26% of floating population. No schistosome eggs were found in the stool examinations in the population. The area with snails was 80.054 6 hm2 in 2016 with an increasing rate of 45.47% compared to that in 2015. The average density of living snails was 0.031 7/0.1 m2. No schistosome-infected snails were found for the last four years and no new area with snails was found for the last three years. No positive livestock or feces were found. The schistosomiasis epidemic situation is stabilized in Yunnan Province in 2016. However, the area with snails and the number of living snails are increasing, and therefore, the schistosomiasis epidemic risk still exists. So, the comprehensive control measures should be strengthened continuously.

Strategy and effect of Oncomelania hupensis snail control in inside-embankment areas in Junshan District, Hunan Province from 1998 to 2017

To explore the strategy and countermeasures of Oncomelania hupensis snail control and evaluate the effect in inside-embankment areas of lake-type schistosomiasis endemic area, for providing the effective method for controlling and interrupting the schistosomiasis transmission. The data of schistosomiasis epidemic and its control and prevention were collected in Junshan District, Hunan Province, and the effect of snail control countermeasures were evaluated and the trend of indexes of snails was drafted in the inside-embankment areas of Junshan District, Hunan Province from 1998 to 2007. The area with snails in the inside embankment areas of Junshan District decreased by 98.43%, from 1 496.66 hm2 in 1998 to 23.48 hm2 in 2017. The occurrence rate and average density of of living snails decreased from 20.61% and 0.45 snail/0.1 m2 in 2003 to 2.06% and 0.03 snail/0.1 m2 in 2017. The highest area with schistosome infected snails was found in 2001 and the total area was 79.36 hm2, however, no infected snails were found since 2007. The total fiscal investment for schistosomiasis prevention and control was 398.857 million RMB in Junshan District, including molluscicide (81.770 9 million RMB) and environment reform (213.5 million RMB) respectively. The comprehensive measures, mainly including the combination of molluscicide and environment reform have gotten a significant effect in snail control and elimination in the inside-embankment areas, but the snail surveillance still need to be strengthened in the historic areas with snails.

Dynamic change of population structure of Oncomelania hupensis

Objective To understand the successive dynamic change of population structure of Oncomelania hupensis during a one-year period, so as to provide the evidence for snail control. Methods A river beach and a ditch infested with O. hupensis snails were selected and longitudinally investigated in the midmonth during one year. The snail survey indices included the survival status, gender, number of whorls, length and width of shell, and gonad development status (measured by the color depth of gonad and the length ratio of gonad to liver), and the monthly snail eggs in the soil were collected and counted simultaneously. In addition, the temperature and humidity of the soil and the daily data of air temperature and precipitation were measured or collected during the study period (every month). Results Both survival rate of snails and live snail density at the two environments were positively correlated with the temperatures of air and soil. With a slight bimodal distribution, the snail survival rate peaked from May to June, and in September. The living snail densities got the highest level in July and September in the river beach, and from April to May in the ditch. The regression equations of snail length (L) and width (W) were Lbeach = 2.355 + 1.678W (F = 2 989.43, P < 0.01) and Lditch = 0.478 + 2.091W (F = 2.989.43, P < 0.01), respectively. The snails were the ones with 4.07-11.81 mm in the length (8.98 ± 0.92) mm in the river beach, and the snails were the ones with 3.63-9.92 mm in the length (7.03 ± 0.82) mm in the ditch. The main snails were the ones with five to eight whorls of shell in the river beach and four to seven whorls of shell in the ditch. The proportions of snails with less than or equal to five whorls (in the river beach) and four (in the ditch) were the highest in May and September, about 20%. The ratios of male and female snails were 1.66 in the river beach and 1.22 in the ditch, respectively. The gonad development status of male and female snails was basically synchronous and had a bimodal abundance period - from April to May and September to October. The numbers of snail eggs in the soil among months were significantly different, reaching the highest in June in the river beach (100.8/0.1 m2), and May in the ditch (82.5/ 0.1 m2). Conclusion The principal periods of breeding and alternation of generations of snails are April-May and SeptemberOctober every year, which should also be the optimal time for mollusciciding in schistosomiasis susceptible zones.

Effect of comprehensive schistosomiasis control strategy with focus on cattle and sheep removal in Junshan District, Yueyang City

Objective To evaluate the effect of comprehensive schistosomiasis control measures with focus on total removal of cattle and sheep in Junshan District, Yueyang City. Methods The retrospective review and field survey were implemented in the pilot villages in Junshan District. The data of Schistosoma japonicum infection status of human, cattle, sheep and Oncomelania hupensis snails, and density of snails were gathered and modeled in the period of 2006 to 2016. Results The prevalence of schistosome infection in residents in the pilot villages decreased from 3.44% in 2006 to 0.59% in 2012 (F = 14.501, P = 0.013). After removal of all the cattle and sheep in 2013, the prevalence of schistosome infection in the residents decreased to zero in 2016 (F = 14.148, P = 0.033). The density of living snails decreased from 0.883 3/0.1 m2 in 2006 to 0.308 8/0.1 m2 in 2012 (F = 76.250, P = 0.005). Conclusion The comprehensive schistosomiasis control strategy with focus on cattle and sheep removal is remarkably effective.

Analysis of epidemic situation of schistosomiasis in Wuhu County from 2012 to 2016

Objective To analyze the epidemic situation of schistosomiasis in Wuhu County from 2012 to 2016, so as to provide the reference for adjusting the control strategy. Methods The data of schistosomiasis prevention and control in Wuhu County from 2012 to 2016 were collected and longitudinally analyzed. Results Since 2013, the average infection rate of schistosomiasis in the population decreased year by year, and the infection rate decreased to 0 in 2016. Since 2012, the infection rate of livestock was 0. The area with Oncomelania hupensis snails decreased year by year, but it drastically rebounded in 2016. No schistosome-infected snails were found since 2012. Conclusions Schistosomiasis epidemic is effectively controlled in Wuhu County, but there is a possibility of recovery. In the next stage, we should focus on strengthening the control of snails and imported infectious sources in order to consolidate the achievements of prevention and control.

Study of schistosomiasis transmission interruption based on intensive agriculture

Objective To study the effect of schistosomiasis transmission interruption model based on intensive agriculture in hilly endemic areas, so as to provide the reference for the similar endemic areas. Methods Based on the development of intensive agriculture in Guanghan City, a comprehensive demonstration area of schistosomiasis control with measures such as new rural construction, hardening ditches, the adjustment of industrial structure and water remediation measures was constructed. Jinhua, Shiguan and Hongyan villages were chosen as the evaluation sites to comparatively analyze the indexes of intensive agriculture and schistosomiasis control effects. Results Compared with the demonstration area before construction, in 2014, the harden rates of ditches and village roads were increased by 49.57% and 39.33% respectively; and the proportion of agricultural machinery increased by 25%. The positive rate of serological tests of schistosomiasis was decreased by 81.74%. The Oncomelania hupensis snail area was decreased from 2.44 hm2 (2007) to 0 (2014). The awareness rate of schistosomiasis control knowledge and correct behavior rate of the residents were increased from 51.28% and 90.85% to 91.29% and 97.69% respectively. The experience of the demonstration area ensured the entire Guanghan District achieved the schistosomiasis transmission interruption criterion at the end of 2014. Conclusions The schistosomiasis control model of intensive agriculture combined with other comprehensive measures has a good effect on interrupting the endemic of schistosomiasis, and it can realize the sustainable development of the agricultural economy and schistosomiasis control.

Molluscicidal effect of suspension concentrate of niclosamide ethanolamine salt

Objective To evaluate the molluscicidal effect of suspension concentrate of niclosamide ethanolamine salt (SCNE) against Oncomelania hupensis snails in laboratory and field. Methods The experiment of SCNE against the snails by using the immersing and spraying methods was performed in laboratory and field, with control groups of wettable powder of niclosamide ethanolamine salt (WPN). Results In the laboratory, LC50(s) of SCNE for 24, 48 h and 72 h by using the immersion method were 0.092 6, 0.062 9 mg/L and 0.054 9 mg/L, respectively. The mortality rates of snails for 24, 48 h and 72 h by using the immersion method were all 100% with the concentrations of 0.25 mg/L. The mortality rates of snails were all 100% while spraying SCNE for 3 d in the laboratory with the concentrations of 0.25 g/m2. In Jiangling County, except 0.5 g/m3 SCNE immersing the snails for 24 h, the mortality rates of snails by using SCNE with the immersing method were all 100%. While the concentration of SCNE was 0.5 g/m3 or above, the mortality rates were all 100% after the use of it with the immersion method for 2 d in Gong'an County. In Jiangling County, the mortality rates of snails by using SCNE 0.5 g/m3 for 1 d, 3 d, and 7 d with the spraying method were 87.5%, 92.82% and 97.40% respectively. While the concentration of SCNE was 0.5 g/m3, the mortality rates were 85.94%, 86.78% and 94.21% respectively after the use of it with the spraying method for 1 d, 3 d, 7 d in Gong'an County, and the molluscicidal effect of SCNE (1.0 g/m2) was higher than that of WPN. Conclusion SCNE has a high molluscicidal effect in the laboratory and field, and it is a novel and simple formulation of niclosamide.

Application of electronic fence technology based on GIS in Oncomelania hupensis snail monitoring

To study the application of Geographic Information System (GIS) electronic fence technique in Oncomelania hupensis snail monitoring. The electronic fence was set around the history and existing snail environments in the electronic map, the information about snail monitoring and controlling was linked to the electronic fence, and the snail monitoring information system was established on these bases. The monitoring information was input through the computer and smart phone. The electronic fence around the history and existing snail environments was set in the electronic map (Baidu map), and the snail monitoring information system and smart phone APP were established. The monitoring information was input and upload real-time, and the snail monitoring information was demonstrated in real time on Baidu map. By using the electronic fence technology based on GIS, the unique "environment electronic archives" for each snail monitoring environment can be established in the electronic map, and real-time, dynamic monitoring and visual management can be realized.

Study on spatial - temporal characteristics of Schistosoma japonicum infections among human in Hunan Province, 2004-2011

Objective To explore the spatial-temporal characteristics and changing regularities of Schistosoma japonicum infections among human from 2004 to 2011. Methods The township level spatial databases of schistosomiasis in Hunan Province from 2004 to 2011 were established, and the related spatial analysis was performed by SPSS 17.0, ArcGIS 10.1 and SaTScan 7.03. Results The schistosome infection rate among human in Hunan Province sharply decreased from 3.0% in 2004 to 0.8% in 2011. However, the rate among residents in parts of some townships in 2011 was still hovering at a higher level (P90 = 2.12%), and the higher rate was distributed along the Oncomelania hupensis snail ridden areas outside embankment. The autocorrelation analysis showed that the global Moran's I for schistosome infection rate among human was 0.34 to 0.53 from 2004 to 2011, and was higher than the expected value (Z > 8.71, P < 0.05). The local G statistics indicated that the positive hotspot high-high clustering areas were mainly near the coast of Dongting Lake from 2004 to 2011, and the number of townships with schistosomiasis endemic in the clustering areas reached 30 to 70. The spatial scan analysis showed that the number of townships in the clustering areas ran up to 145 to 183 from 2004 to 2011. Conclusions The schistosome infection rate among human decreased significantly in Hunan Province from 2004 to 2011. However, the rate in parts of some townships still remains at a comparatively high level, and there are positive spatial correlation and spatial agglomerations in the schistosome infection rate among human, suggesting that the prevention and control work on schistosomiasis in these areas should be strengthened in the future.

Surveillance of schistosomiasis in People's Republic of China in 2015

To analyze the investigation data of the national schistosomiasis surveillance sites in 2015, so as to provide scientific evidences for schistosomiasis control, elimination and surveillance. According to National Schistosomiasis Surveillance Programme (version 2014), 457 surveillance sites were selected, and the investigation data in residents, floating population, domestic animals and Oncomelania hupensis snails were collected and analyzed from four types of endemic counties. A total of 4 468 seropositive cases were detected from 133 350 residents, among which 4 457 residents with seropositive results received the etiological tests, and 71 of them were identified with positive results. Most of them were fishermen and farmers in the middle and old-aged group. The schistosomiasis infection rate was 0.05% in local population. Totally 977 seropositive cases were examined from 85 047 migrant individuals, and 16 positive cases were found out from 966 individuals who took etiological tests, which showed the schistosomiasis infection rate was 0.02% in floating population. Imported cases were found among floating people in four provinces, namely Zhejiang, Hunan, Hubei and Anhui provinces. No acute schistosomiasis cases were reported. A total of 13 406 head of cattle received examinations and only 5 were determined as stool positives. The cattle infection rate was 0.04%. The snail survey covered an area of 22 295.13 hm2 and snails were found in an area of 7 426.63 hm2, including 3.47 hm2 newly detected area with snails. No schistosome-infected snails were found. Based on the collected data from 457 national schistosomiasis surveillance sites of China, the Schistosoma japonicum infection rate is 0.05% in local population which maintains a stably descending trend. In floating population, there are imported schistosome-in-fected persons. Cattle are still a vulnerable species infected with schistosome. Although no infected snails are found, snails are widely distributed in endemic areas. Some provinces detect areas with snails for the first time or the reproduction of snails. The staff in endemic provinces should carry out the surveillance work according to National Schistosomiasis Surveillance Programme (version 2014) to improve the surveillance system, and enhance the sensibility and effectiveness of surveillance work.

Effect of schistosomiasis control in Yangxin County, Hubei Province, 2004-2015

To evaluate the effect of schistosomiasis control and prevention in Yangxin County from 2004 to 2015, so as to provide the evidence for improving the work of schistosomiasis transmission interrupted and elimination in the future. According to the endemic types and endemic regularity of schistosomiasis in Yangxin County, the comprehensive control strategies were adopted, and the programs related to sanitation, water conservancy, forestry, and agriculture were implemented continuously. The schistosomiasis control effects in this county from 2004 to 2015 were analyzed and compared. After the implementation of the schistosomiasis comprehensive control strategies in Yangxin County, the calculated number of patients reduced from 22 240 in 2004 to 1 471 in 2015, the infection rate of residents reduced from 8.57% in 2004 to 0.16% in 2015, the number of patients with acute schistosome infection reduced from 64 in 2004 to 0, and no cases of acute schistosomiasis found since 2009. The infection rate of cattle decreased from 8.87% in 2004 to 0. The area with Oncomelania hupensis snails and the area of susceptible zone reduced from 3 446.21 hm2 and 1 111.59 hm2 in 2004 to 2 285.75 hm2 and 41.28 hm2 in 2015 respectively, and the schistosome-infection rate of snails reduced from 0.76% in 2004 to 0. Since the comprehensive control strategy implemented from 2004, the endemic situation of schistosomiasis in Yangxin County has decreased significantly. However, the harness force of the Fu River as well as the control of infection source of livestock still should be strengthened to consolidate the control achievement.

Oncomelania hupensis status monitoring in Changzhou City, Jiangsu Province from 2013 to 2016

Objective To analyze the Oncomelania hupensis snail distribution and the changes of snail situation in Changzhou City from 2013 to 2016, so as to provide the evidence for formulating the schistosomiasis prevention and control interventions. Methods The data of snail monitoring in Changzhou City from 2013 to 2016 were collected and statistically analyzed. Results The total area with snails was 40.17 hm2 and the newly discovered area was 30.63 hm2 in Changzhou City from 2013 to 2016. In the four years, 3 454 snails were dissected, and no schistosome infected snails were found. There were totally 51 spots with snails, and the areas with snails of different types of marshland, inland and mountain were 12.13 (30.19%), 25.54 hm2 (63.57%) and 2.51 hm2 (6.24%), respectively. In the newly discovered snail environment, the areas of types of marshland and inland were 8.00 hm2 (26.12%) and 22.63 hm2 (73.88%), respectively. The main causes for snail existence were external input and adjacent diffusion. In the past four years, the total snail control area with molluscicides was 71.74 hm2, the consolidated snail control area with molluscicides was 155.15 hm2, and the total environmental modification areas in the current snail spots and historic snail spots were 15.90 hm2 and 11.30 hm2 respectively. Conclusion The diffusion of snails in inland rivers is the key of the newly discovered snail areas in Changzhou City in recent years, and the snail monitoring and control measures should be strengthened in the future.

Surveillance of schistosomiasis transmission risk in Jingmen City, Hubei Province

To investigate the risk factors of schistosomiasis transmission in Jingmen City. The Oncomelania hupensis snails, the wild animal feces, and infection source were selected as the monitoring objects to carry out the schistosomiasis risk monitoring. I-III levels of risk environments were treated with appropriate measures. A total of 52 environments and three water systems were monitored and 1 542 snails were dissected but no Schistosoma infected snails were found. Nine fecal samples were collected from the areas with snails, and no eggs of Schistosoma were found. Eighty-nine samples of cattle/sheep faces, and mice and dogs were collected, and three samples of cattle feces were found with Schistosoma eggs. Five environments were assessed as Grade II, and 48 environments were assessed as Grade III, and 2 environments were assessed as no risk of schistosomiasis transmission. In Jingmen City, the mollusciciding work from May to June could decrease the density of snails and the risk of schistosomiasis transmission efficiently. The schistosome-infected cattle were the main infection source, and therefore, the cattle and snails should be administrated simultaneously.

A multidisciplinary, integrated approach for the elimination of schistosomiasis: a longitudinal study in a historically hyper-endemic region in the lower reaches of the Yangtze River, China from 2005 to 2014

BackgroundAlthough great success has been achieved, schistosomiasis remains a major public health concern in China, and the remaining core endemic regions are concentrated along the middle and lower reaches of the Yangtze River. In this longitudinal study, we evaluated the effectiveness of a multidisciplinary, integrated approach for schistosomiasis elimination in a historically hyper-endemic region in the lower reaches of the Yangtze River, China over the 10-year period from 2005 through 2014.MethodsA three-step roadmap for schistosomiasis elimination was designed in the study site, and multidisciplinary, integrated interventions were implemented by the health, agriculture, water resources development, land and resources, and forestry sectors from 2005 to 2014, including chemotherapy for infected individuals, health education, management of the source of Schistosoma japonicum infection, and intermediate host snail control. The annual number of schistosomiasis patients, S. japonicum infection in humans, bovines and Oncomelania hupensis snails, and water infectivity were observed to assess the effectiveness of the multidisciplinary, integrated approach for the elimination of schistosomiasis.ResultsThere was a tendency towards a gradual decline in both the number of schistosomiasis cases and the prevalence of S. japonicum human infection across the study period from 2005 through 2014. No S. japonicum human infection was detected since 2012, and no acute infection was seen since 2006. During the study period, no infection was found in bovines, and a 0.03% overall infection rate was observed in O. hupensis snails. Since 2009, no infected snails were identified, and the area of both snail habitats and infected snail habitats appeared a reduction over the study period. Following the 3-year multidisciplinary, integrated control, infection control was achieved, and transmission control was achieved after 6-year implementation, with all infected snails and water infectivity eliminated; in addition, the 10-year implementation resulted in interruption of schistosomiasis transmission in the study site in 2014.ConclusionsThe results of the present 10-year longitudinal study demonstrate that the multidisciplinary, integrated approach is effective for the elimination of schistosomiasis as a public health problem in the lower reaches of the Yangtze River, China.

Retrospective analysis of schistosomiasis elimination history in Jingxi City, Guangxi Zhuang Autonomous Region

To understand the schistosomiasis epidemic and control history in Jingxi City, so as to provide the evidence for improving the future work. The data of schistosomiasis prevention and control work were collected and analyzed comprehensively in Jingxi City from 1956-2015. From 1956, the schistosomiasis prevention and control work carried out, and in 1985, Jingxi City reached the standard of schistosomiasis transmission interrupted and no local schistosome infected residents and livestock were found for 36 years. In May 2016, the city reached the national standard of Schistosomiasis Elimination Assessment Review. The cumulative number of schistosomiasis detection of residents was 348 801 person-times, and 10 434 schistosomiasis patients were found. The cumulative number of schistosomiasis detection of cattle was 20 674 head-times, and 590 schistosome infected cattle were found. The cumulative schistosomiasis treatment number of residents was 18739 person-times, and 512 cattle were treated. The cumulative detection area with Oncomelania hupensis was 65 213.25 hm2, and 353.80 hm2 area with O. hupensis snails was found. Jingxi City has reached the standard of schistosomiasis elimination, but there is still recurrence of O. hupensis snails, and the imported infection source exists. Therefore, we should strengthen the monitoring of floating population.

Study on transcriptome of Oncomelania hupensis before and after Schistosoma japonicum invasion I De novo assembly of data by RNA-Seq

To produce a comprehensive transcript dataset of Oncomelania hupensis before and after Schistosoma japonicum infection, so as to provide experimental data for perfecting genetic structural information and excavating related molecular markers of O. hupensis infected by S. japonicum. O. hupensis snails were divided into the following 3 groups: one week after S. japonicum miracidium infection, 4 weeks after S. japonicum miracidium infection, and normal condition. Million high-quality reads were obtained from the normalized cDNA of the pooled samples, which were assembled into transcripts. A total of 63 686 unigenes were identified and were classified into 4 main categories, including general functional prediction (15.36%), signal transduction mechanism (11.75%), posttranslational modification (8.89%), and functional unknown (12.20%). The transcriptome information of O. hupensis snail after the invasion of S. japonicum shows that several genes are significantly up-regulated or down regulated expression, and that the availability of transcriptome information might provide a strong foundation for further understanding the schistosome-snail interaction at the molecular level.

Dynamic simulation analysis of effects of project of ditching for drain on Oncomelania hupensis snail control and flood prevention security in Dongting Lake region

To evaluate the effects of the project of ditching for drain on Oncomelania hupensis snail control and flood prevention security and explore the optimal engineering design plan in Dongting Lake region. A retrospective study was performed on the previous studies about the project of ditching for drain. The reference values of project indices were determined. The outside levee of Nanhu New Distinct of Yueyang City in Dongting Lake region was selected as the study area, and the cross section of marshland perpendicular to the center line of the levee was extracted to research. According to the situations of various water levels, a dynamic simulation was performed on the effect and security of the project of ditching for drain through the software FLAC3D. The retrospective study showed that the project would be effective when the relatively subsoil water level decreased by 0.35 m, and the soil water content decreased correspondingly. The dynamic simulation by FLAC3D showed that the minimum safe distances between transverse ditch 1, vertical ditch and levee toe should be 25 m and 13 m respectively. The digging depth of transverse ditch and vertical ditch should be 1.2 m and 1.0 m respectively. If the width of marshland in drought period was less than 500 m, one transverse ditch was efficient. Otherwise, more transverse ditches should be set with the intervals of 300 m. The project of ditching for drain is an effective ecological snail elimination method. Optimizing the digging depth of ditches and distances between transverse ditches, vertical ditch and levee toe will ensure the effects and security of the project.

Practice of engineering management and its effect on schistosomiasis control in Hankou marshland, Wuhan City

To investigate the Oncomelania hupensis snail control effect of schistosomiasis control engineering in marshland within Wuhan City. The engineering measures including surface barrier removal, molluscicide, flatting surface, topsoil stripping, topsoil covering and ditch renovation were applied to transform Hankou marshland. Then the corresponding technical parameters of engineering measures were put forward. The situation of snails was analyzed before and after the transform project. The total length and area of the project were 6 015 m and 87.21 hm2, respectively, including 17.44 hm2 of topsoil landfill, 52.08 hm2 of topsoil covering and 23 new ditches. After the transformation, the average length of the new groove, the groove top width, groove depth, height difference, and the average values of slopes and ditch bottom slope were all increased, while the average values of the width and height of the ditch were decreased. At the same time, the marshland beach surface had a new slope that the embankment was higher than the river and no living O. hupensis snails were found then. The snail breeding environment in Hankou marshland has been effectively changed by the project. However, the constant monitoring and engineering management are still needed to consolidate the effect.

Advances in researches of biogenic molluscicides

Biogenic molluscicides refer to the use of plants, animals and micro-organisms or their metabolites, and synthesis biomimetic molluscicides to kill Oncomelania hupensis snails. With the rapid development of science and technology, new biogenic molluscicides are continuously emerging and the category also continues to expand. According to the molluscicidal active ingredient and sources, at present, the biogenic molluscicides with in-depth studies include plant-derived molluscicides, micro-organism molluscicides, microbial metabolite molluscicides and animal molluscicides. This paper reviews the advances in the researches of biogenic molluscicides in recent years.

Effect of comprehensive schistosomiasis control measures in Kaihua County from 1996 to 2015

To evaluate the control effect of comprehensive measures of schistosomiasis after its transmission interruption in Kaihua County, Zhejiang Province, so as to provide the references for further consolidation of schistosomiasis control. The data of Oncomelania hupensis snail survey and control, as well as environmental reform in Kaihua County were collected and analyzed from 1996 to 2015. From 1996 to 2015, totally 2 635 snail habitats and 102.75 hm2 area with snails were found, and 125.4 thousand snails were dissected and no one was schistosome infected. The accumulated snail control area was 4 932.98 hm2, and the area with snails was effectively reduced by the comprehensive control measures. The schistosomiasis control effect could be consolidated by the comprehensive control measures emphasizing environmental reconstruction, and the snail surveillance work still should be strengthened.