Nanda Nutan, Singh S P, Prajapati B K, Ranjan Kumud, Kar N P, Sharma S K, Valecha Neena
ICMR-National Institute of Malaria Research, New Delhi, India.
J Vector Borne Dis. 2017 Oct-Dec;54(4):334-340. doi: 10.4103/0972-9062.225838.
BACKGROUND & OBJECTIVES: Entomological investigations were carried out in highly malarious villages under Ujina PHC of District Nuh (Haryana state) which is an epidemic prone area in northwestern region of India. The study was aimed to have an in-depth understanding of the entomological parameters influencing malaria transmission in the study area.
The seasonal prevalence and biological attributes of vector mosquitoes were investigated during 2015 and 2016. Indoor resting vector mosquitoes were collected from human dwellings/cattle sheds and morphologically identified. Anopheles culicifacies were categorized to sibling species by species-specific inversions in polytene chromosomes and An. stephensi to ecological races on the basis of ridge number on egg float. The blood meal source analysis and incrimination studies of vectors were done by counter-current immunoelectrophoresis and enzyme-linked immunosorbent assay, respectively. Insecticide susceptibility test on vectors was performed as per WHO guidelines.
Seasonal abundance of An. culicifacies and An. stephensi in the study area showed variation; the peak densities of both the vectors were observed during monsoon months which correlated well with the average monthly rainfall data. Though both vectors were found to be primarily zoophagic, the human blood index of An. culicifacies (HBI = 0.17) was significantly higher than that of An. stephensi (HBI= 0.02). Analysis of sibling species composition of An. culicifacies population showed that it comprised almost of sibling species A (>98%) which is an established malaria vector. Anopheles culicifacies was incriminated for Plasmodium vivax and P. falciparum circumsporozoite (CS) antigen during monsoon months in 2015 and 2016. Assessment of insecticide susceptibility status of malaria vectors against 0.5% deltamethrin revealed that An. culicifacies is more susceptible (95% mortality) than An. stephensi (85% mortality).
INTERPRETATION & CONCLUSION: The results suggest that An. culicifacies (species A) is playing a major role in malaria transmission in the study area and is almost susceptible to deltamethrin. Timely two rounds of indoor residual spray of synthetic pyrethroid with proper dosage and good coverage would be helpful in reducing vector population and consequently the malaria incidence. In addition, personal protection measures by the community would supplement the major intervention tool (IRS) in decreasing the man-vector contact.
在印度西北部疫情高发地区哈里亚纳邦努赫区乌吉纳初级卫生保健中心下属的疟疾高发村庄开展了昆虫学调查。该研究旨在深入了解影响研究地区疟疾传播的昆虫学参数。
于2015年和2016年调查了媒介蚊虫的季节流行情况和生物学特性。从人类住所/牛棚收集室内栖息的媒介蚊虫并进行形态学鉴定。通过多线染色体上的物种特异性倒位将库氏按蚊分类为姊妹种，并根据卵浮器上的脊数将斯氏按蚊分类为生态型。分别采用对流免疫电泳和酶联免疫吸附测定法进行媒介蚊虫的血餐来源分析和 incriminations 研究。按照世界卫生组织指南对媒介蚊虫进行杀虫剂敏感性试验。
研究地区库氏按蚊和斯氏按蚊的季节丰度存在差异；两种媒介蚊虫的密度峰值均出现在季风月份，这与月平均降雨量数据密切相关。尽管发现两种媒介主要以动物为食，但库氏按蚊的人类血液指数（HBI = 0.17）显著高于斯氏按蚊（HBI = 0.02）。对库氏按蚊种群的姊妹种组成分析表明，其几乎由姊妹种A（>98%）组成，这是一种已确定的疟疾媒介。在2015年和2016年的季风月份，库氏按蚊被确认为感染间日疟原虫和恶性疟原虫环子孢子（CS）抗原。对疟疾媒介对0.5%溴氰菊酯的杀虫剂敏感性状况评估显示，库氏按蚊比斯氏按蚊更敏感（死亡率95%对85%）。
结果表明，库氏按蚊（物种A）在研究地区的疟疾传播中起主要作用，并且几乎对溴氰菊酯敏感。及时进行两轮适当剂量和良好覆盖率的合成拟除虫菊酯室内滞留喷洒将有助于减少媒介种群数量，从而降低疟疾发病率。此外，社区的个人防护措施将补充主要干预工具（室内滞留喷洒）以减少人与媒介的接触。
