Density and hydrostatic settling velocity of Biomphalaria straminea / 中国血吸虫病防治杂志

Objective To understand the eco-hydraulics characteristics of Biomphalaria straminea,the intermediate host of Schistosoma mansoni. Methods The drainage method and settlement tube method were applied to measure B. straminea's den-sity and hydrostatic settling velocity respectively. Results The density of B. straminea was 1.04-1.16 g/cm3,and the average value was 1.08 g/cm3. The hydrostatic settling velocity was 2.32-12.92 cm/s. Conclusions The eco-hydraulics characteristics of B. straminea is different from Oncomelania hupensis,and more attention should be paid to the hydraulic measures for the con-trol of B. straminea.

Analysis on influence of meteorological factors on Oncomelania density / 中华流行病学杂志

Objective To understand the influence of meteorological factors on Oncomelania density in natural condition and provide scientific evidence for the control of the spread of schistosomiasis and Oncomelania.Methods Based on the Oncomelania survey data in spring and ground meteorological observation data of Qianjiang from 1990 to 2014, the first-order autoregressive analysis method was used for trend fitting and disassemble, and the correlation between the change rate of Oncomelania density and various meteorological factors in different periods were analyzed.Results The greatest influence of meteorological factors on Oncomelania density was temperature,followed by precipitation.The average minimum temperature in January and from December to February had predominant influence on Oncomelania density and frame occurrence rate of living Oncomelania (FORLO) respectively.The rise (fall) of average minimum temperature in January by 1 ℃ would lead to the increase (decrease) of Oncomelania density by 5.080％-6.710％;The rise (fall) of average minimum temperature from December to February by 1 ℃ would lead to the increase (decrease) of FORLO by 15.521％-15.928％.The period with the biggest influence of precipitation on Oncomelania density was from November to April, as the rainfall declined ＞20％, drought might occur, which would cause the reduction of Oncomelania density.Sunshine from September to November had some correlations with the change of Oncomelania density and FORLO.Statistical regression models for the change of Oncomelania density, FORLO and meteorological factors based on correlation analysis were established respectively.Conclusion Weed removal in Oncomelania areas before December is beneficial to reduce the surface temperature and soil moisture content, which would result in Oncomelania density reduction in some extent.It' s notable that the winter temperature is in rise in Hubei province along with global climate change, causing the Oncomelania density to increase, to which more attention should be paid.

Study of a new technique on the prevention of Oncomelania hupensis snail dispersal in the irrigation schemes in middle reaches of Yangtze River / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore a new technique to prevent the dispersal of Oncomelania hupensis snail through leading flood for irrigation by floodgate in irrigation schemes.</p><p><b>METHODS</b>Hydromechanical and biological were applied and to combine laboratory experiment with the field observation to form a new multidisciplinary regarding snail biological hydraulics and technical line. Findings including characteristics of hydraulics and biomechanics and move regulation etc. Physics parameter of snails were used to design and construct as well as to exam the effect of facilities and rebuilt floodgate which could prevent the snail dispersal.</p><p><b>RESULTS</b>Through five years efforts, the major achievements were found as: 1) the method in testing the special gravity of snail and snail eggs was determined. 2) the special gravity of snail was (1.8 +/- 0.01) g/cm(3) and special gravity snail eggs was (2.29 +/- 0.01) g/cm(3); the classification method and classified criterion of snail size were made based on geometrical characteristics of snail shell. Six special values indicating dropping and start speed of snail in running water were obtained; Five practical formula of snail dropping and start in water were established; threshold value and movement characteristics in water were observed and tested and move mechanism of snail dispersal in water was also clarified. Based on the findings from fundamental research, the facilities of "precipitation pool for snail" and "leading water from middle level of water body" that could prevent snail dispersal were designed and rebuilt in the endemic area. Through examination to these facilities, the rate of precipitating and blocking of snails reached 100%.</p><p><b>CONCLUSION</b>The achievement of the study provided reliable theoretical basis for the rebuilt of floodgate and to development of models that could prevent the dispersal of snail effectively.</p>

EFFECT OF MICROWAVE ELISA FOR IMMUNODIAGNOSIS OF SCHISTOSOMIASIS JAPONICA / 中国血吸虫病防治杂志

0.05). Cross-reactivity was seen in 1 case of clonorchiasis sinensis by both the methods. Conclusion Microwave ELISA has the advantages of high sensitivity, specificity and rapidity.

INVESTIGATION ON IMPORT WAY OF SCHISTOSOMIASIS AND ONCOMELANIA SNAILS IN THREE GORGES RESERVOIR AREAS / 中国血吸虫病防治杂志

Objective To study the import way of schistosomiasis and the vector snail in Three Gorges Reservoir areas (TGR), so as to provide the reference for the surveillance, early warning of schistosomiasis.Methods A total of 256 movement population in Badong County and Zigui County and 1584 immigrants from TGR to the endemic area of Hubei Province were investigated by questionnaire, and screened by means of IHA and COPT. The farm cattle were surveyed in Badong County and Zigui County. Production of paper mills, the source of papermaking raw material, flowers and trees in gardens were investigated for snail survey. At the same time, current situation of immigrants in TGR was investigated. Social data (statistic yearbook, etc) and policy data of development of TGR were collected. Results No farm cattle from endemic area of schistosomiasis was found. In Hubei reach of TGR, the movenment population were mainly from the endemic area of schistosomiasis in Hubei Province. The positive rate of both IHA and COPY was 0 57%(1/175); the positive rate of both IHA in emigrants from TGR was 1 01%(12/1186). No Oncomelania snail was found in the introduced flowers and trees in garden. In paper mills, no reed from the endemic area of schistosomiasis was found. Migrants′ living and sanitary condition were improved after moving,but the production was not well arranged. Orange industry, travel industry, animal husbandry and fishery should be developed preferentially in the future. Conclusion Migrants from TGR to the endemic area of schistosomiasis and the movement population will be the mainly infection source. The problem on cattle as the infection source should be paid attention. It can't be excluded that snail will enter TGR together with the raw material for paper mills or flowers and trees. To develop orange industry will be good for the control of schistosomiasis; but the development of animal husbandry, fishery and travel industry will increase the risk of import of the infection source and snails to TGR.

DYNAMIC OBSERVATIONS ON SNAIL SITUATION AND WILD FAECES POLLUTION IN MARSHLANDS IN PILOT AREAS OF HUBEI PROVINCE / 中国血吸虫病防治杂志

Objective To understand the dynamic changes of snail situation and wild faeces pollution in marshlands in the pilot areas after leveling embankment for flood running and moving people from outside embankment to town for providing the scientific basis of schistosomiasis control in the same type areas. Methods Shishou City,Jiangxia District,Tuanfeng County and Huangzhou District were selected as the pilot areas. Snails were surveyed by the systematic and environmental sampling. Wild faeces were also investigated. The data were processed by Excel. Results Snail areas in Huangzhou Yeluzhou increased by 12.71%,in the others it did not change. For the snail density,there was a decline trend in Jiangxia Sanjiaozhou from 1999 to 2001,but it increased in 2002 obviously;in Huangzhou Yeluzhou it decreased in 2000,but increased again from 2001 to 2002;in Tuanfeng Luohuozhou it was fluctuation;it did not change in Shishou Fuxingzhou. Except Shishou City,the other three sites had infected snails distribution. The densities of wild faeces in the pilot areas were 1.14～15.60/hm~2. The positive rates of wild faeces were 1.35%～37.21%. Conclusion The marshlands in pilot areas were seriously polluted by wild faeces. There seemed to be an increase trend in the snail density. Snail areas did not change significantly in the last few years. However,the high transmission areas will expand. So the snail survey and snail control should be strengthened.

POTENTIAL IMPACT OF SOUTH-NORTH WATER TRANSFER PROJECT ON TRANSMISSION AND DISTRIBUTION OF SCHISTOSOM1ASIS JAPONICA / 中国血吸虫病防治杂志

Objective To understand the potential impact of south-north water transfer project on transmission and distribution of Schistosomiasis japonica, and to put forward the countermea-sures of prevention of the disease transferring into other places. Methods The information on the progress of south-north water transfer project and factors related to the distribution of Schistosoma juponicum were collected, and the suggestions on improving the countermeasures were obtained through the group discussions and field visits. Results The potential impact of the project on the disease transferring is existed, mainly the disease transferring will be through the Lixia River basin in Jiangsu Province, and Chaohu areas of Anhui Province in the east route, and Sihu areas of Hubei Province in the middle route. The snail transferring northward will be affected both by the project and global warming, as a result, the endemic areas of Schistosomiasis will probably transfer into the Hongzehu and Chaohu areas in the future. Conclusion In the east route of the project, if the project is not combined with Schistosomiasis control, the endemic areas of Schistosomiasis will extend into other regions, the loss in the society and economy will be very large.

COST-EFFECTIVENESS AND-BENEFIT ANALYSIS OF WORLD BANK LOAN PROJECT ON SCHISTOSOMIASIS CONTROL IN QIANJIANG CITY / 中国血吸虫病防治杂志

Objective To evaluate the cost-effectiveness and -benefit of the World Bank Loan Project on Schistosomiasis Control in Qianjiang City. Methods According to the national scheme the cost-effectiveness and cost-benefit of the project were analysed. Results After the project was carried out for 9 years, poputation schistosome infections rate decreased by 56.48%; cattle infections rate decreased by 48.08%; snail areas reduced 1224 hm 2(42.76%). Infected snail areas reduced 273 hm 2(17.13%). Snail infections rate decreased by 97.04%. The investment for infections rate decreased by 1% in 100 people was 1384.47 yuan. The investment for infections rate decreased by 1% in 100 head of cattle was 3386.96 yuan. The investment to reduce 1 hm 2 snail ares was 8935.63 yuan. Conclusion For one yuan investment, the benefit was 7.96 yuan and the total of the net benefit was 106784700 yuan in 9 years.

STUDY ON INCREASING MOLLUSCICIDAL EFFECT BY COMPLEX NICOTINANILIDE WITH NICLOSAMIDE / 中国血吸虫病防治杂志

Objective To explore the increment of molluscicidal effect and reduction of the cost as well as increasing snail control area by complex commercial molluscicides. Methods Nicotinanilide and niclosamide were combined with the proportion of 1∶1 (The complex of short term was complex molluscicide), and then the snail control tests by immersion and spraying methods were performed using the complex molluscicide in laboratory and field. Meanwhile, the snails climbing from water as they contacted with molluscicide was observed. Results Under the temperature 23-25℃ in lab and 8-19℃ in the field, 0.4 mg/L of the complex by immersion for 48 h, the mortalities of the snails were 100% and 97% respectively. Using 0.4 g/m 2 of complex by spraying for 48 h in lab and the field, the mortalities of the snails were 100% and 81.1% respectively. The rate of snails climbing from water in the complex group decreased by 72.1% compared with the nicotinanilide group. The difference between the two groups was obviously significant (P

ANALYSIS OF EPIDEMIC CHANGES IN THE EPIDEMIOLOGICAL OBSERVATION POINTS OF SCHISTOSOMIASIS IN HUBEI PROVINCE FROM 1990 TO 1998 / 中国血吸虫病防治杂志

Objective To master the trend of schistosomiasis epidemic by means of established observation points and give the scientific reference for the control decision making henceforth. Methods Three villages of schistosomiasis with highly prevalence in Hubei Province were selected as observation points, and their epidemiological status were observed from 1990-1998. Results The schistosomiasis prevalence was considerably decreasing in the 3 villages, from high epidemic areas into medium or light areas. Conclusion It is a right tactic to use the selective population chemotherapy and control snail in high transmission areas of schistosomiasis in high epidemic areas.