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ABSTRACT: To define and evaluate the malaria transmission potential in the Yangtze River, following construction of the Three Gorges Reservoir.
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).
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.
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.
Biomedical and Environmental Sciences 01/2013; 26(1):54-62. · 1.35 Impact Factor
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ABSTRACT: Both falciparum and vivax malaria were historically prevalent in China with high incidence. With the control efforts, the annual incidence in the whole country has reduced to 0.0001% except in some areas in the southern borders after 2000. Despite this, the re-emergence or outbreak of malaria was unavoidable in central China during 2005-2007. In order to understand the role of the vector in the transmission of malaria during the outbreak period, the vector capacity of An. sinensis in Huanghuai valley of central China was investigated.
The study was undertaken in two sites, namely Huaiyuan county of Anhui province and Yongcheng county of Henan province. In each county, malaria cases were recorded for recent years, and transmission risk factors for each study village including anti-mosquito facilities and total number of livestock were recorded by visiting each household in the study sites. The specimens of mosquitoes were collected in two villages, and population density and species in each study site were recorded after the identification of different species, and the blood-fed mosquitoes were tested by ring precipitation test. Finally, various indicators were calculated to estimate vector capacity or dynamics, including mosquito biting rate (MBR), human blood index (HBI), and the parous rates (M). Finally, the vector capacity, as an important indicator of malaria transmission to predict the potential recurrence of malaria, was estimated and compared in each study site.About 93.0% of 80 households in Huaiyuan and 89.3% of 192 households in Yongcheng had anti-mosquito facilities. No cattle or pigs were found, only less than 10 sheep were found in each study village. A total of 94 and 107 Anopheles spp. mosquitos were captured in two study sites, respectively, and all of An. sinensis were morphologically identified. It was found that mosquito blood-feeding peak was between 9:00 pm and 12:00 pm. Man biting rate of An. sinensis was 6.0957 and 5.8621 (mosquitoes/people/night) estimated by using half-night human bait trap method and full-capture method, respectively. Human blood indexes (HBI) were 0.6667 (6/9) and 0.6429 (18/28), and man-biting habits were 0.2667 and 0.2572 in two sites, respectively. Therefore, the expectation of infective life and vector capacity of An. sinensis was 0.3649-0.4761 and 0.5502-0.7740, respectively, in Huanhuai valley of central China where the outbreak occurred, which is much higher than that in the previous years without malaria outbreak.
This study suggests that vivax malaria outbreak in Huanhuai valley is highly related to the enhancement in vector capacity of An. sinensis for P. vivax, which is attributed to the local residents' habits and the remarkable drop in the number of large livestock leading to disappearance of traditional biological barriers.
Parasites & Vectors 07/2012; 5:136. · 2.94 Impact Factor
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ABSTRACT: To study the anopheline species and composition in villages at different altitudes, Muotuo County.
Six villages with different altitudes were selected as the investigation spots, i.e. Gande, Zhucun, Damu, Motuo, Didong and Beibeng with an altitude 1 966 m, 1 510 m, 1 408 m, 1 178 m, 853 m and 831 m, respectively. Human-baited net traps, cow-baited traps and light traps were set up to collect adult mosquitoes. The trapped mosquitoes were counted and identified according to morphological criteria. Following the classification, the mosquitoes were killed by chloroform and dried on silica-gel, and transported to the laboratory where they were stored at -20 degrees C. Species of Anopheles maculatus complex were identified with multiple PCR method.
5 410 anopheline mosquitoes were collected. Two mosquitoes were captured in high altitude village, one was Anopheles gigas bailieyi, while the other was damaged and unable to identify. There were 541 (36.9%) An. pseudowillmori, 906 An. willmori (61.7%) and 21 An. peditaeniatus (1.4%) collected in semi-high altitude villages; 260 (76.3%) An. pseudowillmori, 2 An. willmori (0.6%) and 79 An. peditaeniatus (23.2%) trapped in middle altitude village; and 3265 (90.7%) An. pseudowillmori, 19 An. willmore (0.5%) and 315 An. peditaeniatus (8.8%) trapped in low altitude villages.
An. pseudowillmori, An. willmore and An. peditaeniatus make the main anopheline composition. The proportion of An. willmore is higher than An. pseudowillmori in semi-high altitude villages, while An. pseudowillmori take the absolute predominance in middle and low altitude villages.
Zhongguo ji sheng chong xue yu ji sheng chong bing za zhi = Chinese journal of parasitology & parasitic diseases 08/2011; 29(4):285-8.
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ABSTRACT: 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.
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.
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.
The situation of the malaria cases in the national sentinel surveillance points could be estimated,using the CRM.
Zhonghua liu xing bing xue za zhi = Zhonghua liuxingbingxue zazhi 12/2007; 28(11):1105-7.
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ABSTRACT: To make a field investigation on the affecting factors of malaria outbreak in a village of Congjiang County, Guizhou Province.
The investigation was made in August, 2006. Filter paper dry blood samples were taken for indirect fluorescent antibody test (IFAT) from all the 495 residents above 1 year-old in the village where an outbreak of malaria was reported. Questionnairing was conducted in 423 villagers over 10 years-old, covering malaria history in the past 2 years, knowledge on malaria and its control, use of mosquito nets, and out-door sleeping habit. Data on febrile outpatients were collected from the records of the township health center for analyzing the compliance of the patients in seeking medical services. Mosquito collecting by human-bait before mid-night, and in mosquito nets and cattle pens in early morning was performed for mosquito composition and man-biting rate.
Re-examination of the 42 positive blood smears confirmed 12 positives of P. vivax infection. The malaria incidence in 18 d was 2.1%, including 4 cases clinically diagnosed. The antibody positive rate of IFAT in the population was 8.7% (43/495) with a positive GMRT of 20.6, overall GMRT of 10.6; the IFAT positive rate in the age group of under 5 was 7.5% (3/40) with a GMRT of 25.1. The rate of seeking medical advice among febrile patients was 81.3% (118/145), 78.8% (93/118) of which being in the village clinic. The average time of going to a doctor after fever was 3.9 days, 37.4% (195/521) and 3.3% (17/521) were in 4-6 days and over 10 days respectively, with the longest 26 days. The average knowledge rate on malaria was 25.5% (108/423), with 17.1%, 29.2% and 40.0% in the groups of illiteracy, primary school and high school education respectively. A statistical significance was found between primary school/high school education and the illiteracy (P<0.01). The average rate of using mosquito nets was 31.0% (131/423), out-door sleeping rate was40.7% (172/423). The radical cure rate in 2004 and 2005 was 68.2% (15/22) and 48.3% (14/29) respectively. In addition to Anopheles sinensis, An. anthropophagus and An. minimus also existed in rooms and nets with a man-biting rate of 0.0566 and 0.0755 respectively.
Three species of anopheline mosquitoes are the important transmitting vectors. Poor self-protection, outdoor sleeping habit, delayed examination and treatment, and irregular chemotherapy among the residents are the main factors resulting malaria outbreak.
Zhongguo ji sheng chong xue yu ji sheng chong bing za zhi = Chinese journal of parasitology & parasitic diseases 07/2007; 25(3):225-9.
