Shililu Josephat, Ghebremeskel Tewolde, Seulu Fessahaye, Mengistu Solomon, Fekadu Helen, Zerom Mehari, Asmelash G E, Sintasath David, Mbogo Charles, Githure John, Brantly Eugene, Beier John C, Novak Robert J
National Malaria Control Program, Division of Communicable Diseases Control, Ministry of Health, PO Box 212 Asmara, Eritrea.
J Am Mosq Control Assoc. 2004 Jun;20(2):155-64.
Entomological studies were conducted over a 24-month period in 8 villages to establish the behavior patterns, seasonal densities, and variation in entomological inoculation rates (EIRs) of Anopheles arabiensis, the main vector of malaria in Eritrea. A total of 5,683 anopheline mosquitoes were collected through indoor sampling (1,613), human-landing catches (2,711), and outdoor pit shelters (1,359). Overall, An. arabiensis was the predominant species at all of the study sites, with its population density increasing during the rainy season. Peak indoor-resting densities was observed during September and October. Human landing indices for An. arabiensis averaged 1.9 and 3.8 per person per night in October and September, respectively. Peak biting and landing rates occurred between 2000-2200 h and 0100-0300 h. Of the total number of bites, 44.7% occurred between 1800 and 2300 h, and at least 56.5% of the total bites occurred outdoors, indicating that the species was partially exophagic. The fed to gravid ratio for An. arabiensis in indoor-resting collections was 2:1, indicating some degree of exophily. The sporozoite rates (SRs) for An. arabiensis ranged from 0.54% in the Anseba zone to 1.3% in the Gash-Barka zone. One mosquito each of An. d'thali (SR = 0.45%) and An. cinereus (SR = 2.13%) was found to be positive. Of the total positive An. arabiensis (n = 64), 18.2% came from human-landing collections outdoors. Blood-meal analysis by enzyme-linked immunosorbent assay for An. arabiensis indicated that this species was partially zoophilic with a human to bovine ratio of 2:1 being recorded. The EIR profiles indicated that malaria transmission is highly seasonal, increasing during the wet season and declining drastically during the dry season. On average, the greatest risk of infection occurs in Hiletsidi, in the Gash-Barka zone (6.5 infective bites per month). The exophilic behavior and early evening biting of An. arabiensis present obstacles for control with treated bed-nets and indoor residual spraying within the context of integrated malaria control, and call for greater focus on strategies such as larval control.
在厄立特里亚的8个村庄进行了为期24个月的昆虫学研究,以确定阿拉伯按蚊(该国疟疾的主要传播媒介)的行为模式、季节密度以及昆虫学接种率(EIRs)的变化情况。通过室内采样(1613只)、人饵诱捕(2711只)和室外坑式诱捕器(1359只),共收集到5683只按蚊。总体而言,阿拉伯按蚊在所有研究地点都是优势物种,其种群密度在雨季增加。9月和10月观察到室内栖息密度峰值。阿拉伯按蚊的人饵指数在10月和9月分别平均为每人每晚1.9次和3.8次。叮咬和着陆率峰值出现在20:00 - 22:00时和01:00 - 03:00时。在总叮咬次数中,44.7%发生在18:00至23:00时之间,且至少56.5%的总叮咬发生在室外,这表明该物种有部分外食习性。室内栖息采集的阿拉伯按蚊饱血雌蚊与孕卵雌蚊的比例为2:1,表明有一定程度的外栖性。阿拉伯按蚊的子孢子率在安塞巴地区为0.54%,在加什 - 巴尔卡地区为1.3%。发现一只达氏按蚊(子孢子率 = 0.45%)和一只灰按蚊(子孢子率 = 2.13%)呈阳性。在所有阳性的阿拉伯按蚊(n = 64)中,18.2%来自室外人饵采集。对阿拉伯按蚊进行的酶联免疫吸附测定血餐分析表明,该物种有部分嗜动物性,记录的人血与牛血比例为2:1。EIRs曲线表明疟疾传播具有高度季节性,在雨季增加,在旱季急剧下降。平均而言,感染风险最高的是加什 - 巴尔卡地区的希莱齐迪(每月6.5次感染性叮咬)。阿拉伯按蚊的外栖行为和傍晚早期叮咬给综合疟疾控制背景下的经处理蚊帐和室内滞留喷洒控制带来了障碍,因此需要更加关注幼虫控制等策略。