[A study on the effect of Oncomelania hupensis hupensiss killed with niclosamide in China].
OBJECTIVE
To study the effect of Oncomelania hupensis hupensis of niclosamide, and exploring the main influencing factors.


METHODS
The samples of Oncomelania hupensis hupensis were collected from 37 sampling sites in 33 counties of 10 provinces by means of stratified random sampling methods in accordance with the categories of Oncomelania hupensis hupensis habitats. Samples were randomly located into study group and control group. Oncomelania hupensis hupensis of the study group was marinated in different concentration liquor of niclosamide which was confected with water for 24 hours or 48 hours, then LC50 of niclosamide by which Oncomelania hupensis hupensis was killed and amount calculated. The influencing factors of the mortality of Oncomelania hupensis hupensis in the study group was statistically analyzed by 2 test and by multiple logistic regression using SPSS 13.0 statistical software.


RESULTS
The mortality of Oncomelania hupensis hupensis of the two test groups which were marinated in 0.5 mg/L liquor for 48 hours and 1.0 mg/L liquor for 24 hours was 100%. The effect of Oncomelania hupensis hupensis killed by niclosamide was markedly reduced along with the reduction of drug concentration. The average LC50 rates of niclosamide liquor by which Oncomelania hupensis hupensis killed for the 24 hours and 48 hours in the study group, were 0.0939 mg/L and 0.0625 mg/L, respectively. There was significant difference between the two test groups (chi(2) = 5.001, P <0.01) . In determinate range of concentration, the mortality of Oncomelania hupensis hupensis showed significant difference among the geographic types of habitat ( chi(2) = 4.264, P < 0.05). By means of multiple logistic regression using SPSS 13.0 statistical software, the estimate value of coefficient of regression on the influence factors, drug concentration, test time and the geographic types of habitat were 2. 047 ( OR = 5. 573), 0.263 ( OR = 2.924) and 0. 187- 0.210 ( OR = 1.969- 2. 560), respectively.


CONCLUSIONS
Niclosamide could kill Oncomelania hupensis hupensis effectively. The main influencing factors on the efficacy of niclosamide by which Oncomelania hupensis hupensis was killed, appeared to be drug concentration, time of testing and the geographic types of habitat.
Lv
Yuan
Y
Department of Epidemiology, Medical College of Hunan Normal University, Changsha 410006, China.
Yi
Shang-hui
SH
Liu
Tao-cheng
TC
Yi
Yin-sha
YS
Wang
Yao-zhu
YZ
D000818:Animals; D002681:China; D017753:Ecosystem; D008975:Molluscacides / Q000633:toxicity*; D009534:Niclosamide / Q000633:toxicity*; D012908:Snails / Q000187:drug effects*
D008975:Molluscacides; D009534:Niclosamide