加纳沿海科蓬-昂-塞地区旱季改善干预措施的蚊虫种群疟疾传播特征。

Characterization of malaria transmission by vector populations for improved interventions during the dry season in the Kpone-on-Sea area of coastal Ghana.

机构信息

School of Public Health, University of Ghana, Legon, Ghana.

出版信息

Parasit Vectors. 2012 Sep 26;5:212. doi: 10.1186/1756-3305-5-212.

DOI:10.1186/1756-3305-5-212

PMID:23013551

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC3495633/

Abstract

BACKGROUND

Malaria is a major public health problem in Ghana. We present a site-specific entomological study of malaria vectors and transmission indices as part of an effort to develop a site for the testing of improved control strategies including possible vaccine trials.

METHODS

Pyrethrum spray catches (PSC), and indoor and outdoor human landing collections of adult female anopheline mosquitoes were carried out over a six-month period (November 2005 - April 2006) at Kpone-on-Sea, a fishing village in southern Ghana. These were morphologically identified to species level and sibling species of the Anopheles gambiae complex further characterized by the polymerase chain reaction (PCR). Enzyme-linked immunosorbent assay was used to detect Plasmodium falciparum mosquito infectivity and host blood meal sources. Parity rate was examined based on dilatation of ovarian tracheoles following dissection.

RESULTS

Of the 1233 Anopheles mosquitoes collected, An. gambiae s.l. was predominant (99.5%), followed by An. funestus (0.4%) and An. pharoensis (0.1%). All An. gambiae s.l. examined (480) were identified as An. gambiae s.s. with a majority of M molecular form (98.2%) and only 1.8% S form with no record of M/S hybrid. A significantly higher proportion of anophelines were observed outdoors relative to indoors (χ2 = 159.34, df = 1, p < 0.0000). Only An. gambiae M molecular form contributed to transmission with a high degree of anthropophily, parity rate and an estimated entomological inoculation rate (EIR) of 62.1 infective bites/person/year. The Majority of the infective bites occurred outdoors after 09.00 pm reaching peaks between 12.00-01.00 am and 03.00-04.00 am.

CONCLUSION

Anopheles gambiae M molecular form is responsible for maintaining the status quo of malaria in the surveyed site during the study period. The findings provide a baseline for evidence-based planning and implementation of improved malaria interventions. The plasticity observed in biting patterns especially the combined outdoor and early biting behavior of the vector may undermine the success of insecticide-based strategies using insecticide treated nets (ITN) and indoor residual spray (IRS). As such, novel or improved vector interventions should be informed by the local malaria epidemiology data as it relates to vector behavior.

摘要

背景

疟疾是加纳的一个主要公共卫生问题。我们进行了一项特定地点的疟疾媒介和传播指数的昆虫学研究，作为开发一个用于测试改良控制策略的地点的努力的一部分，包括可能的疫苗试验。

方法

在加纳南部的一个渔村科蓬-昂-塞亚，我们进行了为期六个月（2005 年 11 月至 2006 年 4 月）的拟除虫菊酯喷雾捕获（PSC）、室内和室外成年雌性按蚊的人体降落收集。这些蚊种经过形态学鉴定到种水平，并用聚合酶链反应（PCR）进一步鉴定冈比亚按蚊复合体的姊妹种。酶联免疫吸附试验用于检测恶性疟原蚊的感染性和宿主血餐来源。根据解剖后卵巢气管的扩张，检查了产仔率。

结果

在所收集的 1233 只按蚊中，冈比亚按蚊（99.5%）占优势，其次是曼蚊（0.4%）和法雷蚊（0.1%）。所有检查的冈比亚按蚊（480 只）均被鉴定为冈比亚按蚊 s.s.，其中大多数为 M 分子型（98.2%），只有 1.8%为 S 型，没有 M/S 杂种的记录。与室内相比，户外观察到的按蚊比例明显更高（χ2=159.34，df=1，p<0.0000）。只有冈比亚按蚊 M 分子型对传播有贡献，具有高度的嗜人性、产仔率和估计的昆虫接种率（EIR）为 62.1 个感染性叮咬/人/年。大多数感染性叮咬发生在晚上 09 点以后，在 0 点至 1 点和 3 点至 4 点之间达到高峰。

结论

冈比亚按蚊 M 分子型在研究期间维持了调查地点疟疾的现状。研究结果为基于证据的规划和实施改良疟疾干预措施提供了基线。观察到的噬咬模式的可塑性，特别是媒介的户外和早期噬咬行为的组合，可能会破坏基于杀虫剂的策略的成功，如使用杀虫剂处理过的蚊帐（ITN）和室内滞留喷洒（IRS）。因此，新型或改良的媒介干预措施应根据与媒介行为相关的当地疟疾流行病学数据来制定。