ABSTRACT
Objective To study the impact of precipitation and water level on acute schistosomiasis for providing reference to control acute schistosomiasis in advance. Methods The historical data on precipitation and water level as well as acute schistosomiasis from 2003 to 2007 in Eastern, Southern and Western Dongting Lake regions were collected and analysed for the correlation between acute schistosomiasis and precipitation and water level in local areas. Results Acute schistosomiasis gradually decreased year by year from 2003 to 2007. Compared with 2003, the number of acute schistosomiasis in 2007 reduced by 95.37%. There was no outbreak of acute schistosomiasis from 2005 to 2007.In the period of peak acute schistosomiasis, the average monthly rainfall reduced from year to year for the successive 5 years. There was a significantly correlation between acute schistosomiasis and monthly average water level. Conclusions The acute schistosomiasis is directly affected by nature factors and has a close correlation with the rainfall and water level in Dongting Lake regions.
ABSTRACT
Objective To evaluate the fun ct ioning status and the effects of snail control in the different kinds of sluices in Dongting Lake regions. Methods Field invest igation was conducted for 85 modified sluices which aimed to preventing snails f rom spreading from 2000 to 2001 in Dongting Lake regions. The survey was used fo r the collection of data in terms of snails' situation in the irrigation canals and ditches inside the embankments where those modified sluices served as the in tervention of schistosomiasis control. The field trials of 85 sluices in 4 kinds (the abandoned, the equipped with lengtlened and lowered underwater pipes, the affiliated by snails retention tanks and the equipped with nets). were carried out to observe their effects of filtering snails, during which a g iven number of snails were cast in the front of the projects and recollected in the rear of the ones by means of the nets framed 40 holes per 25.4 mm.Results Eight sluices with the lengthened an d lowered underwater pipes were on trial for 22-28 hours and during which 2000 dyed snails was cast, yet no snails were detected in the rear. In 10 abandoned s luices, 9 were firmly sealed according to their design, and their functions of d rainage and irrigation inside embankment were replaced by other water conservanc y facilities. Up to 2003, 67 of 85 modified sluices have shown an effect on tra pping snails after 4-10 years of the running, and its effective rate arr ived at 78.8%. Conclusion Three kinds of sluices, i .e. the abandoned, the equipped with the lengthened and lowered underwater pipes , and the affiliated by snails retention tanks, show the capacity of trapping sn ail s, yet the one equipped with nets was unsuitable for application because of its difficulties in the long term maintenance. [
ABSTRACT
Objective To explore susceptibility of praziquantel(PQT) against Schistosoma japonicum in the repeated chemotherapy areas in Dongting Lake region of China. Methods Sixty mice were divided into two groups, and infected respectively by cercariae released from the infected snails which were collected from new and old endemic areas. After 5 weeks, the mice in each group were divided into control groups and treatment groups (PQT group). The mice in each PQT group were treated with a single oral dose of praziquantel (600 mg/kg). Three weeks post treatment, mice were dissected, and the number of adults, the stool eggs per gram (EPG), the liver EPG and the hatching rates were observed. Results The worm reduction rates of the PQT groups of new and old epidemic areas were 98.24% and 98.71% respectively, and the stool egg reduction rates 99.94% and 99.64%, the liver egg reduction rates 75.85% and 73.10%,and there were no significant differences between the new and old endemic areas. The stool hatching test was positive in the control groups, and negative in the PQT groups. Conclusion Susceptibility of praziquantel against Schistosoma japonicum does not decrease in repeated chemotherapy areas in Dongting Lake region.