Short report:: Entomologic inoculation rates and Plasmodium falciparum malaria prevalence in Africa
Short report:: Entomologic inoculation rates and Plasmodium falciparum malaria prevalence in Africa
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DOI：
10.4269/ajtmh.1999.61.109
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发表时间：
1999-07-01
影响因子：
3.3
通讯作者：
Githure, JI
中科院分区：
文献类型：
--
作者：
Beier, JC;Killeen, GF;Githure, JI
疟疾感染的流行病学模式受调节按蚊媒介种群的环境参数支配。疟疾寄生虫传播的强度通常用昆虫学接种率(EIR)表示，即媒介叮咬率乘以感染子孢子期疟疾寄生虫的蚊子比例的乘积。疟疾在非洲的传播强度变化很大，每年的EIR从每人每年1到1000次感染叮咬不等。疟疾控制项目通常寻求通过减少或消除蚊子传播疟疾寄生虫来降低疟疾的发病率和死亡率。这份报告评估了非洲31个地点的数据，以建立年度EIR与恶性疟原虫感染流行之间的基本关系。大多数站点的疟疾流行率与年度EIR的对数呈线性关系(r(2)=0.71)。一些每年有5次感染性叮咬的地点恶性疟原虫流行率超过40%。当传播超过每年15次感染性叮咬时，没有流行率为50%的场所。年EIR在200或更高时，患病率一直与80%相关。EIR和恶性疟原虫流行之间的基本关系可能存在于东非和西非以及不同的生态区，这一基本关系令人信服地表明，只有将EIR降低到每人每年不到一次感染性叮咬的水平，才可能大幅降低疟疾流行率。分析还强调，与疟疾流行的传统测量或基于医院的感染或发病率测量相比，EIR是一种更直接的传播强度测量方法。因此，疟疾现场项目需要同时考虑昆虫学和临床对传播控制措施有效性的评估。
Epidemiologic patterns of malaria infection are governed by environmental parameters that regulate vector populations of Anopheles mosquitoes. The intensity of malaria parasite transmission is normally expressed as the entomologic inoculation rate (EIR), the product of the vector biting rate times the proportion of mosquitoes infected with sporozoite-stage malaria parasites. Malaria transmission intensity in Africa is highly variable with annual EIRs ranging from < 1 to > 1,000 infective bites per person per year. Malaria control programs often seek to reduce morbidity and mortality due to malaria by reducing or eliminating malaria parasite transmission by mosquitoes. This report evaluates data from 31 sites throughout Africa to establish fundamental relationships between annual EIRs and the prevalence of Plasmodium falciparum malaria infection. The majority of sites fitted a linear relationship (r(2) = 0.71) between malaria prevalence and the logarithm of the annual EIR. Some sites with EIRs < 5 infective bites per year had levels of P. falciparum prevalence exceeding 40%. When transmission exceeded 15 infective bites per year, there were no sites with prevalence rates < 50%. Annual EIRs of 200 or greater were consistently associated with prevalence rates > 80%. The basic relationship between EIR and P. falciparum prevalence, which likely holds in east and west Africa, and across different ecologic zones, shows convincingly that substantial reductions in malaria prevalence are likely to be achieved only when EIRs are reduced to levels less than 1 infective bite per person per year. The analysis also highlights that the EIR is a more direct measure of transmission intensity than traditional measures of malaria prevalence or hospital-based measures of infection or disease incidence. As such, malaria field programs need to consider both entomologic and clinical assessments of the efficacy of transmission control measures.