Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.
BMC Infect Dis. 2012 Oct 30;12:275. doi: 10.1186/1471-2334-12-275.
Rapid demographic growth in Douala city, Cameroon, has resulted in profound ecological and environmental changes. Although demographic changes can affect anopheline mosquito breeding sites, there is a lack of understanding about the epidemiological impact that such changes might have on vector ecology and malaria transmission.
A 12-month entomological study was conducted in a highly populated district of Douala called Ndogpassi. Adult mosquitoes were collected using two methods: 1) human landing catches (HLC); and 2) Centers for Disease Control and Prevention (CDC) light traps; these methods were used twice monthly from January to December 2011. Mosquito genus and species were identified with morphological and molecular diagnostic tools. The sampling efficiency of the CDC light trap and HLC were compared. Anopheles gambiae infection with Plasmodium falciparum was detected using ELISA. Susceptibility to DDT, permethrin, and deltamethrin insecticides were also determined.
A total of 6923 mosquitoes were collected by HLC (5198) and CDC light traps (1725). There was no equivalence in the sampling efficiency between light traps and human landing catches (P > 0.01). With 51% of the total, Culex was the most common, followed by Anopheles (26.14%), Mansonia (22.7%) and Aedes (0.1%). An. gambiae ss (M form) comprised ~98% of the total anophelines collected. An. gambiae had a biting rate of 0.25 to 49.25 bites per human per night, and was the only species found to be infected with P. falciparum. A P. falciparum infection rate of 0.5% was calculated (based on enzyme-linked immunosorbent assays using the circumsporozoite surface protein). The entomological inoculation rate was estimated at 31 infective bites per annum. Insecticide susceptibility tests on An. gambiae females revealed a mortality rate of 33%, 76% and 98% for DDT, permethrin and deltamethrin, respectively. The West African kdr allele (L1014F) was detected in 38 of the 61 An. gambiae analyzed (62.3%).
The present study revealed seasonal malaria transmission in Douala. High levels of An. gambiae were detected along with a high prevalence of insecticide resistance in this vector population. These findings highlight the need to promote use of insecticide-impregnated bed nets in Douala.
喀麦隆杜阿拉市人口迅速增长，导致生态和环境发生了深刻变化。尽管人口变化会影响按蚊滋生地，但人们对这些变化可能对病媒生态学和疟疾传播产生的流行病学影响知之甚少。
在杜阿拉一个人口稠密的地区 Ndogpassi 进行了为期 12 个月的昆虫学研究。使用两种方法收集成蚊：1）人体诱蚊诱捕器（HLC）；2）疾病控制和预防中心（CDC）诱蚊灯；2011 年 1 月至 12 月，每月两次使用这些方法进行采样。使用形态学和分子诊断工具对蚊虫属种进行鉴定。比较了 CDC 诱蚊灯和 HLC 的采样效率。使用 ELISA 检测疟原虫感染。还确定了蚊虫对滴滴涕、氯菊酯和溴氰菊酯杀虫剂的敏感性。
HLC（5198 只）和 CDC 诱蚊灯（1725 只）共收集了 6923 只蚊子。诱蚊灯和人体诱蚊诱捕器的采样效率没有可比性（P＞0.01）。Culex 是最常见的蚊虫，占总数的 51%，其次是按蚊（26.14%）、曼蚊（22.7%）和伊蚊（0.1%）。收集的按蚊中，An. gambiae ss（M 型）约占 98%。按蚊的叮咬率为每人每晚 0.25 至 49.25 次，是唯一发现感染疟原虫的蚊种。根据环子孢子表面蛋白酶联免疫吸附试验（ELISA）计算，疟原虫感染率为 0.5%。估计昆虫学接种率为每年 31 次感染性叮咬。对雌性按蚊进行的杀虫剂敏感性试验显示，滴滴涕、氯菊酯和溴氰菊酯的死亡率分别为 33%、76%和 98%。在所分析的 61 只 An. gambiae 中，检测到西非 kdr 等位基因（L1014F）的有 38 只（62.3%）。
本研究显示杜阿拉存在季节性疟疾传播。在该蚊种群中发现了高水平的 An. gambiae 和高度的杀虫剂耐药性。这些发现强调需要在杜阿拉推广使用经杀虫剂处理的蚊帐。
