湖北嗜人按蚊传播疟疾的阈值研究

Study on the Thresholds of Malaria Transmission by Anopheles anthropophagus in Hubei Province

目的 研究湖北嗜人按蚊传播疟疾的阈值和潜势,为当地疟疾监测、预警与防治提供科学的评价指标。方法 选取湖北嗜人按蚊分布区疟疾发病率较高的随州市府河镇严家畈村为调查点,于2001年7～8月现场调查媒介按蚊的叮人率、经产蚊比例、人血指数和吸血趋性,调查人群疟疾发病率、原虫率以及疟疾患者发病至接受治疗的平均间隔期,收集观察期间的平均气温数据。根据基本繁殖率概念计算以媒介按蚊临界叮人率为指标的传播疟疾阈值。结果嗜人按蚊趋吸人血的比例为92.6％(63/68),在人房的构成比为91.5％(97/106),人血指数是中华按蚊的12.5倍(0.50/0.04),媒介能量是中华按蚊的6.5倍(0.9448/0.1449),实际叮人率是其临界叮人率(0.2823)的3.5倍(0.98916/0.2823)。疟疾发病率为0.65％(12/1844),小学生原虫率为0.51％(1/198)。结论 湖北省试点嗜人按蚊的实际叮人率需要降低71.5％,当地由嗜人按蚊引起的疟疾传播将被阻断。

Objective To study the thresholds and potential of malaria transmission by Anopheles anthropophagus in Hubei Province and provide indicators for the disease surveillance, early warning, prevention and control in the locality. Methods From July to August 2001, field investigations on vectors and malaria situation were carried out in the village of Yanjiafan, Suizhou City, where the malaria incidence was high. The entomological investigations included the man-biting rate, the proportion of parous anophelines, the human blood index and the blood preference. The others included malaria incidence and parasite rate in human population, the intervals from episode to treatment of the cases, and collection of data on the mean temperature in the area. Based on the formula of basic reproductive rate, the critical man-biting rate was esti- mated. Results 92. 6% (63/68) of An. anthropophagus were found to have human blood meals, it occupied 91. 5% (97/106) of the mosquitoes in human dwellings, its human blood index and vectorial capacity were 12. 5 times (0. 50/ 0. 04) and 6. 5 times (0. 9448/0. 1449) higher than those of An. sinensis. The critical man-biting rate was 0. 2823 and the adjusted man-biting rate was 3. 5 times of its critical man-biting rate (0. 9892/0. 2823). The malaria incidence was 0. 65% (12/1844) and the parasite rate in pupils was 0. 51% (1/198). Conclusion A reduction of the adjusted man-biting rate of An. anthropophagus by 71. 5% is needed for interrupting malaria transmission by this vector in the study area.