[Strengthening the research on novel molluscicides to accelerate the progress towards elimination of schistosomiasis].

Oncomelania hupensis is the only intermediate host of Schistosoma japonicum, and control of Oncomelania snails is an important measure to control and interrupt the transmission of schistosomiasis. Therefore, snail control plays a very critical role in the national schistosomiasis control programmes of China. Pyriclobenzuron, which was recently developed by National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, is the latest great advance in the research on molluscicides and is expected to solve the problem of toxicity to fish, which is worthy of expanding experiments.

[Effect of cutting beach group on Oncomelania hupensis snail control in south of Shaobo Lake, Jiangsu Province].

OBJECTIVE: To evaluate the effect of Oncomelania hupensis snail control of cutting the beach group in the south of Shaobo Lake. METHODS: The general situation of the project of cutting the beach was surveyed, and the snail distribution was surveyed and the results were compared before and after cutting the beach in the beach group. RESULTS: The area of cutting beach was 928.33 hm2, the cubic meter of earthwork was 1 717.00 m3, the area of dumping ground was 425.76 hm2, the beach surface elevation was 3.2 m after cutting the beach, and the beach surface was fallen to 1.0 m under the ordinary water level. The area with snails was 44.69 hm2 before cutting the beach in 2011 but the area with snails was 1.78 hm2 after cutting the beach in 2018. The area with remaining snails was declined by 96.02% in 2018 as compared with that in 2011, and surviving snails were distributed on the uncut beach face. CONCLUSIONS: In Shaobo Lake, the O. hupensis snail breeding environment is eliminated by raising or lowering the beach, so it is an effective measure of snail control in lake regions.

[Ecological characteristics of Oncomelaniahupensisand water conservancy combined with schistosomiasis prevention and control].

The control of water conservancy ecosystem for Oncomelaniahupensissnails and water conservancy combined with schistosomiasis prevention and control are an important part of the comprehensive control of schistosomiasis in China. It has played an important role in the prevention and control of schistosomiasis in a long-term. The technique regulation for water con-servancy combined with schistosomiasis prevention has nearly 30 years'development gradually and formed a series of technical specification. Its theoretical basis is associated with the water ecology and hydraulics of snails. This paper mainly reviews the soil, grass, water, light and others related to ecological elements of the snails, and the water conservancy ecological control technique of snails and the current water conservancy measurements combined with schistosomiasis prevention and control in the field of schistosomiasis prevention and control, and puts forward the proposals for the water conservancy combined with schistosomiasis prevention and control technology development in the future. The water conservancy combined with schistosomiasis prevention and control should have further development in the new situation in order to play a more important role for schistosomiasis elimination in China.

[Evaluation of implementation effect of schistosomiasis control program in Jiangsu Province from 2010 to 2015].

OBJECTIVE: To evaluate the actual effect of the schistosomiasis control program in Jiangsu Province from 2010 to 2015. METHODS: A total of 67 schistosomiasis-endemic counties in 10 cities were selected, and a combination of retrospective investigation and on-site investigation was adopted to collect and record the epidemic data of the counties from 2010 to 2015, and a retrospective survey database of epidemic situation was established. The effects of integrated control strategies with both Oncomelania hupensis snail control and infection source control were evaluated. RESULTS: From 2010 to 2015, 2 465 911 persons who lived in endemic areas were detected for schistosomiasis, with 16 974 positive cases of blood examinations, and 8 positive cases of fecal examinations. Totally 5 145 people with advanced schistosomiasis were treated and 40 460 people with the history of schistosome cercarial-infested water contact received the expanded chemotherapy. A total of 127 636 cattle raised in the endemic areas were detected, and 51 619 cattle (head-times) with the history of cercarial-infested water contact also received the expanded chemotherapy. The area with snails control by molluscicides was 18 604.84 hm2. By the end of 2015, schistosomeinfected snails had not been found and there was no zoological schistosome infection for 5 consecutive years, and in addition, there had been no acute schistosome-infected persons for 6 consecutive years in the whole province. The area with snails dropped to 1 977.18 hm2, with a decreasing rate of 55.24% compared with that in 2010. CONCLUSIONS: After the implementation of the plan for the prevention and control of schistosomiasis in Jiangsu Province (2010-2015), the prevention and control of schistosomiasis has achieved remarkable effects and realized the goal of the plan.

[Field molluscicidal effect of water-free formulations of niclosamide ethanolamine salt against Oncomelania hupensis snails in a marshland].

OBJECTIVE: To evaluate the molluscicidal effects of various water-free formulations of niclosamide ethanolamine salt against Oncomelania hupensis in the field of marshlands along the Yangtze River. METHODS: The river beach with O. hupensis snails were selected as the test field in the marshland along the Yangtze River in Pukou District, Nanjing City. A molluscicidal experiment was carried out by the mechanical dusting method with the dustable powder (DP), powder-granule (PG), granule (GR) of niclosamide ethanolamine salt respectively. The snail mortality, corrected mortality, and the reduced rate of snails' density were parallel compared among DP, PG and GR. RESULTS: On the 3rd day after the dusting, the snail mortality rates were 66.67%, 67.24%, and 66.87% in the DP, PG, and GR groups respectively, on the 7th day after the dusting, the snail mortality rates were 75.36%, 79.73%, and 73.97% in the DP, PG, and GR groups respectively, and there was no significant difference among the groups (χ2 = 0.006, 0.895, both P > 0.05). On the 15th day after the dusting, the snail mortality rates were 86.92%, 72.86%, and 71.43% in the DP, PG, and GR groups respectively, and there was a significant difference among the groups (χ2 = 9.709, P < 0.01). The snail mortality in the DP group was significantly higher than that in the PG, and GR groups. The curves of the snail corrected mortality and reduced rate of snails'density presented steadily rising trends in the DP group, but presented falling trends in the PG and GR groups on the 15th day after the dusting. CONCLUSIONS: The molluscicidal effect of DP is stable and effective in the marshland along the Yangtze River, but the drift of the powder is still not effectively controlled. It is necessary that the different dosage forms are perfected.

[Strategy of transmission interruption of schistosomiasis and its effects in Runzhou District, Zhenjiang City, Jiangsu Province].

OBJECTIVE: To evaluate the effects of the strategy of transmission interruption of schistosomiasis in Runzhou District, Zhenjiang City, Jiangsu Province. METHODS: The comprehensive prevention and control strategy was carried out in RunzhouDistrict, Zhenjiang City, Jiangsu Province. The strategy was relied mainly on the Oncomelania hupensis snail control, extended chemotherapy of schistosomiasis in residents and the health education. The infection rate of schistosomiasis in residents, area with snails, area with snails controlled, and the rates of awareness and correct behavior of schistosomiasis were as evaluation indexes. RESULTS: The area with snails controlled was 7 091.50 hm2 in Runzhou District, Zhenjiang City from 2001 to 2016. The area with snails reduced year by year from 2001 to 2016. There was a negative correlation between the coverage intensity of snail control and the area with snails (r = -0.874, P = 0). There were 1 703 serum positive and 199 fecal positive people of schistosomiasis in the permanent residents from 2001 to 2016. These serum and fecal positive people of schistosomiasis were all treated with praziquantel. The serum positive rate of schistosomiasis in the permanent residents dropped to below 1.0% after 2005. The fecal positive patients were not found in 2004 and later. Totally 189 639 people received the questionnaire survey for the knowledge of schistosomiasis control from 2001 to 2016. The rates of awareness and correct behavior of schistosomiasis were raised in the residents year by year. The goal of the transmission interruption of schistosomiasis came to true in Runzhou District, Zhenjiang City in 2016. CONCLUSIONS: The comprehensive prevention and control strategy including mainly the snail control, extended chemotherapy of schistosomiasis and health education could achieve the goal of transmission interruption of schistosomiasis in the areas of marshland along the Yangtze River.

[Survey of schistosomiasis KAP and influencing factors of behaviors among residents in Jiangsu Province].

OBJECTIVE: To understand the schistosomiasis control knowledge, attitude, and practice (KAP), and influencing factors of behaviors among residents in Jiangsu Province, so as to provide the evidence for making effective health education and health promotion models. METHODS: The probability proportionate to size sampling (PPS) and multi-stage sampling methods were adopted to sample the research objects. A questionnaire survey of schistosomiasis control KAP was conducted in the residents of 16 to 69 years old in schistosomiasis endemic areas of Jiangsu Province, and the results were statistically analyzed. RESULTS: The total awareness rate of the participants was 95.98% for schistosomiasis control knowledge. The correct rates of attitude and practice were 89.06% and 77.43%, respectively. The awareness/correct rates of knowledge, attitude and practice reduced in turns significantly (χ2 =1 282.96, P < 0.01). The knowledge awareness rate of fishermen and boatmen was 90.98%, but their attitude correct rate was only 53.81% ( χ2 =120.52, P < 0.01). The unconditional logistic regression analysis showed that with the education level increasing, their practice correct rate rose, and the participants with the college degree or above had a higher correct rate compared to illeterate ones (OR = 6.411, 95% CI: 4.896-8.395). The practice correct rate of the fisher-men and boatmen was only 5.1% of the rate of the farmers (OR = 0.051, 95% CI: 0.029-0.091). CONCLUSIONS: The total awareness rate of basic knowledge of schistosomiasis prevention and control in the residents of Jiangsu Province has reached the requirements in the "National Schistosomiasis Control Long-term Planning Outline (2004-2015)", but the correct rate of behaviors is low. The education level, occupation and residential areas affect the health behaviors of schistosomiasis prevention and control. Therefore, it is necessary to carry out targeted health promotion activities to promote the formation of healthy lifestyle and behaviors.

[Effect of water conservancy schistosomiasis control projects combined with molluscicide to control Oncomelania hupensis snails in rivers connecting with Yangtze River in Pukou District, Nanjing City].

OBJECTIVE: To evaluate the effect of the water conservancy schistosomiasis control projects combined with molluscicide to control Oncomelania hupensis snails in the rivers connecting with the Yangtze River. METHODS: The water conservancy schistosomiasis control projects of Zhujiashan River, Qili River and Gaowang River were chosen as the study objects in Pukou District, Nanjing City. The data review method and field investigation were used to evaluate the effect of the water conservancy schistosomiasis control projects combined with molluscicide to control O. hupensis snails. RESULTS: After the projects of the water level control and concrete slope protection and mollusciciding were implemented, the snails in the project river sections were completely eliminated. The snail diffusion did not happen in the inland irrigation area too. In the outside of the river beach, though the snails still existed, the snail densities plunged below 1.0 snail per 1.0 m2. CONCLUSIONS: The comprehensive measures of the combination of water level control, concrete slope protection and mollusciciding can effectively control and eliminate the snails, and prevent the snails from spreading.

[Study on Oncomelania hupensis snails infected with Schistosoma japonicum miracidia under different conditions in snail-existent non-endemic areas of schistosomiasis in Nantong City].

OBJECTIVE: To understand the forming cause of the Oncomelania hupensis snail-existent non-endemic areas of schistosomiasis (SENEAS), and to verify the conclusion of previous studies, so as to provide the evidence for schistosomiasis monitoring in such areas in Nantong City, Jiangsu Province. METHODS: The controlled field tests were carried out to observe the O. hupensis snails artificially infected by schistosome miracidia in SENEAS. The influence of the soil from SENEAS and the endemic areas on O. hupensis snails artificially infected by miracidia were observed. RESULTS: All the experimental snails could be infected by schistosome miracidia except the smooth-shell snails from Tangyuan Village in the controlled field test environment of SENEAS or the endemic areas. The infection rates of the smooth-shell snails were lower than those of the ribbed-shell snails, but there were no statistically significant differences. The mortality rates of the smooth-shell snails were higher than those of the ribbed - shell snails, which were statistically significant (χ2Xindian = 135.118, χ2Shuangdian = 122.836, χ2Baipu =154.436, χ2Dingyan = 138.288, χ2Control = 151.923, all P < 0.01). There were no significant differences in the infection rates of snails between each test group of the soil from SENEAS and the endemic areas (χ2Rugao = 0.071, χ2Rudong = 0.216, both P > 0.05). Also there was no significant difference between each test group and the control group without soil (χ2 = 7.148, P > 0.05). CONCLUSIONS: It is likely to form the spread of schistosomiasis in SENEAS in Nantong City with sufficient amount of infection source of schistosomiasis imported. It is still necessary to implement the surveillance of schistosomiasis and O. hupensis snails in Nantong City.

[Molluscicidal effect of niclosamide ethanolamine salt powder - granula against Oncomelania hupensis].

OBJECTIVE: To evaluate the molluscicidal effect of niclosamide ethanolamine salt powder-granula (PG) against Oncomelania hupensis. METHODS: The molluscicidal experiment was carried out by the dusting method with niclosamide ethanolamine salt 4% PG. The experiments were respectively done in the laboratory and the tidal flats wetlands. At the same time, the niclosamide ethanolamine salt 4% dustable powder (DP) was as the control group. The single blind method was used for the quality control. The corrected mortality and the median lethal concentration (LC50) were compared between PG and DP in the molluscicidal experiment of the laboratory. The corrected mortality and the reduced rate of snails'density were compared between PG and DP in the tidal flats wetlands. RESULTS: The mortality rates of the snails were 96.67% and 100% respectively on 1 d after dusting 4.0 g/m2 of 4% PG and 2.0 g/m2 of 4% DP in the laboratory. The results showed that the mortality rates of the snails were higher with 4% DP than 4% PG in each dosage (t1 d = 3.60, P < 0.01). The LC50 (s) of 1d, 3 d, 7 d after dusting the molluscicide also showed that the molluscicidal effects of DP were better than PG. The corrected mortality rates were 91.71%, 92.91%, 90.57%, 85.33% and 71.09%, 90.11%, 90.13%, 85.26% on 3 d, 7 d, 15 d, 30 d after dusting with 4% PG and 4% DP, respectively, in the fields. Statistics showed that the mortality rates of snails were higher on 3 d, 7 d after dusting with PG than DP (χ23 d = 731.57, χ27 d = 25.90, P < 0.01), but there were no significant differences between PG and DP on 15d, 30d after dusting (χ215 d = 0.53, χ230 d = 0.01, P > 0.05). CONCLUSIONS: 4% PG has both the adsorption of powder and the penetrability of the granules. The molluscicidal effects of 4% PG and 4% DP are almost the same. However, the drift of the powder was still not effectively controlled. This problem need to be further studied.