Quantitative Microbial Risk Assessment of / 生物医学与环境科学（英文）

We aimed to assess the risks of

[Science and technology-led technical innovation provides a driving force to accelerate the progress of malaria elimination].

Since the malaria elimination program was launched, a series of scientific research programs have been conducted in Jiangsu Province, including epidemiology, pathogenic biology and vector biology, and some novel techniques and approaches have been established, which provides a strong safeguard for malaria elimination in Jiangsu Province and achieves the effective interruption of local malaria transmission. In addition, these tools provide new insights into and technical support for the national and global malaria elimination programs.

Science and technology-led technical innovation provides a driving force to accelerate the progress of malaria elimination / 中国血吸虫病防治杂志

Since the malaria elimination program was launched, a series of scientific research programs have been conducted in Jiangsu Province, including epidemiology, pathogenic biology and vector biology, and some novel techniques and approaches have been established, which provides a strong safeguard for malaria elimination in Jiangsu Province and achieves the effective interruption of local malaria transmission. In addition, these tools provide new insights into and technical support for the national and global malaria elimination programs.

Application of Auto-regressive Linear Model in Understanding the Effect of Climate on Malaria Vectors Dynamics in the Three Gorges Reservoir / 生物医学与环境科学（英文）

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 for exploring the relationship between the climatic factors and its malaria vector density from 1997 to 2007 using the auto-regressive linear model regression method. The result indicated that both temperature and precipitation were better modeled as quadratic rather than linearly related to the density of Anopheles sinensis.

Application of structural equation models for elucidating the ecological drivers of Anopheles sinensis in the three gorges reservoir.

OBJECTIVE: To identify the major ecological drivers for malaria vector density using the structural equation model (SEM) in the Three Gorges Reservoir. METHOD: An 11-year longitudinal surveillance of malaria vector as well as its related ecological factors was carried out in the Three Gorges Reservoir. The Delphi method was used to identify associated ecological factors. The structural equation model was repeatedly corrected and improved by the corrected index, combined with the actual situation. The final model was defined by relative simplicity, best fitting as well as the practicality. RESULT: The final model indicated that the direct effects of temperature, livestock, humidity, and breeding on the vector were 0.015, -0.228, 0.450, 0.516 respectively, their total effects on the vector were 0.359, -0.112, 0.850, and 0.043 through different pathways. CONCLUSION: SEM was effective and convenient in elucidating the mechanism by which malaria vector dynamics operated in this study. It identified that the breeding had the highest direct effect on vector and played a key role for mediating effect of temperature and humidity.

Malaria transmission potential in the Three Gorges Reservoir of the Yangtze River, China / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To define and evaluate the malaria transmission potential in the Yangtze River, following construction of the Three Gorges Reservoir.</p><p><b>METHODS</b>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).</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Comparative evaluation of light-trap catches, electric motor mosquito catches and human biting catches of Anopheles in the Three Gorges Reservoir.

The mosquito sampling efficiency of light-trap catches and electric motor mosquito catches were compared with that of human biting catches in the Three Gorges Reservoir. There was consistency in the sampling efficiency between light-trap catches and human biting catches for Anopheles sinensis (r = 0.82, P<0.01) and light-trap catches were 1.52 (1.35-1.71) times that of human biting catches regardless of mosquito density (r = 0.33, P>0.01), while the correlation between electric motor mosquito catches and human biting catches was found to be not statistically significant (r = 0.43, P>0.01) and its sampling efficiency was below that of human biting catches. It is concluded that light-traps can be used as an alternative to human biting catches of Anopheles sinensis in the study area and is a promising tool for sampling malaria vector populations.

Chemotherapy-based control of ascariasis and hookworm in highly endemic areas of China: field observations and a modeling analysis / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

[Establishment and application of ascariasis transmission mathematical models in China].

OBJECTIVE: To establish ascariasis transmission mathematical models and apply them to predict field status. METHODS: Cuiping District in Sichuan Province, Jinxian County in Jiangxi Province and Yueyang County in Hunan Province were selected as the investigation sites. The Ascaris lumbricoides infection rates and mean worm burdens of baseline, 1 month and 1 year later after deworming were acquired by field surveys. The transmission models on population dynamics, distribution and infection rate were developed. The model parameters obtained through the field data were substituted into models to predict the infection level one year after deworming. The predicted values were compared with the actual survey data, and the sensitivity analysis was performed to analyze factors related to the chemotherapy measures. RESULTS: The infection rates of Cuiping, Jinxian and Yueyang at baseline were 28.79%, 20.35% and 20.72%, respectively, with mean worm burdens of 1.32, 0.65 and 0.48, respectively. Those one year after chemotherapy were 30.10%, 7.51% and 0.94%, respectively, with mean worm burdens of 1.04, 0.56 and 0.34, respectively. The predict values were all in the range of the 95% confidence interval of the actual values. The sensitivity analysis showed that the treatment coverage rate and the treatment frequency were the important factors influencing the disease benefits (infection rate and mean worm burden). CONCLUSIONS: The ascariasis transmission mathematical models have been established which fit the actual field data well. Therefore, they can provide theoretical basis for setting ascariasis control specifications and optimizing the control strategies.

Application of the indirect fluorescent antibody assay in the study of malaria infection in the Yangtze River Three Gorges Reservoir, China.

BACKGROUND: China Yangtze Three Gorges Project (TGP) is one of the biggest construction projects in the world. The areas around the Three Gorge Dam has a history of tertian malaria and subtertian malaria epidemic, but there are no overall data about malaria epidemics before the completion of the project. The objective of this study was to get a reliable baseline on malaria infection in the Yangtze River Three Gorges reservoir area and to provide reference data for future studies about the impact of the project on malaria epidemics. METHODS: Two surveys of malaria infection were carried out in area, at six-month intervals in May and October 2008. About 3,600 dual specimens blood film samples for parasite diagnosis and filter paper blood spots for serology (using the immunofluorescence antibody test) were collected from the general population, including school populations, whenever possible. RESULTS: The overall percentage of positive response of the same population during post-transmission periods was about twice (1.40/0.72) of that in pre-transmission. Positive individuals under 15 years of age were detected in all the localities. CONCLUSION: A certain extent of malaria infection existed in this area. Additional studies are needed to determine the length of malaria experience, and chemotherapeutic intervention as well as the distribution of main vectors for transmission in this area.

Current status of soil-transmitted nematode infection in China / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To carry out national surveys for ascertaining the current status and trends of soil-transmitted nematode infections in China, providing scientific basis for further developing control strategies.</p><p><b>METHODS</b>In 1988-1992 (hereinafter abbreriated as "survey in 1990"), a stratified cluster random sampling method was used in the survey. In 2001-2004 (hereinafter abbreriated as "survey in 2003"), in order to compare with the survey in 1990, two-characteristic stratified cluster random sampling method was used and 687 investigation spots were sampled from the 2848 spots selected in the survey in 1990. Kato-Katz thick smear method was used to examine the eggs of soil-transmitted nematodes in fecal samples.</p><p><b>RESULTS</b>The prevalence rates were 53.6% and 19.6% for soil-transmitted nematodes, 14.6% and 6.120% for hookworms, 44.6% and 12.7% for Ascaris lumbricoides, 17.4% and 4.630% for Trichuris trichiura in survey 1990 and survey 2003, respectively. The prevalence rates of soil-transmitted nematodes were higher in 13 provinces than the average level in China in the survey in 1990, and higher in 8 provinces than the average level in the survey in 2003. The prevalence of hookworms, Ascaris lumbricoides, Trichuris trichiura and the overall prevalence of soil-transmitted nematodes were higher in females than in males. It is estimated from the results of survey in 2003 that the number of persons with soil-transmitted nematode infections in the country is about 129 million, less than that in the survey in 1990.</p><p><b>CONCLUSION</b>The prevalence of soil-transmitted nematodes has declined considerably but is still relatively high in some provinces and autonomous regions. Control activities and socioeconomic development may have contributed to the decreased prevalence.</p>

Evaluation on current malaria prevalence using capture-recapture method in national sentinel surveillance points malaria / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore the feasibility of using the capture-recapture method (CRM) for national malaria sentinel surveillance program and to evaluate the malaria prevalence at those points.</p><p><b>METHODS</b>By CRM to compare data on malaria cases reported from national sentinel surveillance program and those from the registration of case report system (CRS). Analysis was made to express the difference regarding the number of cases in order to get the estimates and the incidence rate.</p><p><b>RESULTS</b>The incidence in the relative higher epidemic area, unstable epidemic area and relative lower epidemic area were 1247.30/100000, 171.50/100000 and 46.10/100000, respectively. The rate of miss-reporting malaria cases in these areas were 65.20% ,45.32% and 66.67%, respectively.</p><p><b>CONCLUSION</b>The situation of the malaria cases in the national sentinel surveillance points could be estimated,using the CRM.</p>

In vitro potentiation of antimalarial activities by daphnetin derivatives against Plasmodium falciparum / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To screen the antimalarial compounds of daphnetin derivatives against Plasmodium falciparum in vitro.</p><p><b>METHOD</b>Plasmodium faciparum (FCC1) was cultured in vitro by a modified method of Trager and Jensen. Antimalarial compounds were screened by microscopy-based assay and microfluorimetric method.</p><p><b>RESULTS</b>DA79 and DA78 showed potent antimalarial activity against Plasmodium falciparum cultured in vitro.</p><p><b>CONCLUSION</b>Though the relationship between the structures of daphnetin derivatives and their antimalarial activities has not been clarified yet, this study may provide a new direction for discovery of more potential antimalarial compounds.</p>