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Open Access Research

Optimizing molluscicide treatment strategies in different control stages of schistosomiasis in the People’s Republic of China

Guo-Jing Yang123, Le-Ping Sun12, Qing-Biao Hong12, Hong-Ru Zhu12, Kun Yang12, Qi Gao12 and Xiao-Nong Zhou45*

Author Affiliations

1 Jiangsu Institute of Parasitic Diseases, Wuxi, Jiangsu, 214064, People’s Republic of China

2 Key Laboratory on Control Technology for Parasitic Diseases, Ministry of Health, Wuxi, Jiangsu, 214064, People’s Republic of China

3 School of Public Health and Primary Care, the Chinese University of Hong Kong, Satin, Hong Kong

4 National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, 200025, People’s Republic of China

5 WHO Collaborating Center for Malaria, Schistosomiasis and Filariasis, Key Laboratory on Biology of Parasite and Vector, Ministry of Health, Shanghai, 200025, People’s Republic of China

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Parasites & Vectors 2012, 5:260  doi:10.1186/1756-3305-5-260

Published: 14 November 2012

Abstract

Background

The application of chemical molluscicides is still one of the most effective measures for schistosomiasis control in P. R. China. By applying diverse molluscicide treatment scenarios on different snail densities in the field, we attempted to understand the cost-effectiveness of molluscicide application so as to prescribe an optimal management approach to control intermediate host snail Oncomelania hupensis under acceptable thresholds based on the goal of the National Schistosomiasis Control Programme.

Methods

The molluscicidal field trial was carried out in the marshland of an island along the Yangtze River, Jiangsu province, P.R. China in October 2010. Three plots in the island representing low-density, medium-density and high-density groups were identified after the baseline survey on snail density. Each snail density plot was divided into four experimental units in which molluscicide (50% niclosamide ethanolamine salt wettable powder) was applied once, twice, trice and four times, respectively. The logistic regression model to correlate snail mortality rate with the covariates of number of molluscicidal treatment and snail density, and a linear regression model to investigate the relationship between cost-effectiveness and number of molluscicidal treatment as well as snail density were established.

Results

The study revealed that increase in the number of molluscicide treatments led to increased snail mortality across all three population density groups. The most cost-effective regimen was seen in the high snail density group with a single molluscicide treatment. For both high and low density groups, the more times molluscicide were applied, the less cost-effectiveness was. However, for the median density group, the level of cost-effectiveness for two applications was slightly higher than that in one time.

Conclusions

We concluded that different stages of the national schistosomiasis control/elimination programme, namely morbidity control, transmission control and transmission interruption, should utilize different molluscicide treatment strategies to maximize cost-effectiveness.

Keywords:
Schistosomiasis; Molluscicides; Cost-effectiveness; Control strategy