Chemotherapy-based Control of Ascariasis and Hookworm in Highly Endemic Areas of China:Field Observations and a Modeling Analysis

Objective Our objective was to systematically evaluate chemotherapy-based control of ascariasis and hookworm infection and make predictions of the effectiveness of repeated mass treatment at different levels of coverage in highly endemic areas of China. Methods Field surveys were carried out to acquire the ascariasis and hookworm prevalence and intensity （mean worm burden） at baseline, one month and one year later. We calculated model parameters based on the survey data, then incorporated them into a quantitative framework to predict the prevalence and intensity one year later. Sensitivity analyses were performed to assess the influence of the chemotherapy measures on prevalence and intensity, and model simulations were performed to evaluate the feasibility of achieving the proposed transmission control criteria under different chemotherapy measures. Results The predicted prevalence and intensity one year from baseline were within the 95% confidence interval of actual values. As treatment frequency or coverage increased, the prevalence and intensity decreased. Model simulations show that many rounds of treatment are needed to maintain the prevalence at a low level in highly endemic areas of China. Conclusion We should select different combinations of treatment frequency, coverage and drug efficacy according to available resources and practical attainable conditions. Mathematical modeling could be used to help optimize the chemotherapeutic scheme aiming at specific parasitic species and areas, and to direct the establishment of soil-transmitted helminthiasis control criteria in China.

Application of Auto-regressive Linear Model in Understanding the Effect of Climate on Malaria Vectors Dynamics in the Three Gorges Reservoir

It is important to understand the dynamics of malaria vectors in implementing malaria control strategies. Six villages were selected from different sections in the Three Gorges Reservoir fc,r exploring the relationship between the climatic ｜：actors and its malaria vector density from 1997 to 2007 using the auto-regressive linear model regressi^n method. The result indicated that both temperature and precipitation were better modeled as quadratic rather than linearly related to the density of Anopheles sinensis.

Malaria Transmission Potential in the Three Gorges Reservoir of the Yangtze River, China

Objective To define and evaluate the malaria transmission potential in the Yangtze River, following construction of the Three Gorges Reservoir. Methods Six villages, namely, Kaixian, Fengjie, Wanzhou, Fuling, Yubei, and Zigui were selected for investigating the malaria transmission potential in the reservoir. Transmission potential was estimated by mathematical modeling and evaluation of the local malaria situation. Factors that influenced the transmission potential were analyzed using Poisson regression analysis in combination with Grey Systematic Theory （based on evaluation by the Delphi method）. Results Indirect fluorescent antibody data and the incidence of malaria in the local population were consistent with the malaria transmission potential calculated for the area. Multivariate Poisson regression analysis showed a statistically significant association between the riparian zone and the man‐biting rate. Conclusion The risk of a malaria epidemic can be forecasted using the malaria transmission potential parameters investigated here which was closely correlated with the riparian zone.

Quantitative Microbial Risk Assessment of Cryptosporidium and Giardia in Public Drinking Water in China

We aimed to assess the risks of Cryptosporidium and Giardia infections associated with drinking water for local residents,based on a quantitative microbial risk assessment,in three densely populated regions of China.In total,45 source water samples and 45 treated water samples were collected from June to December 2014.