Gebhardt Mary E, Searle Kelly M, Kobayashi Tamaki, Shields Timothy M, Hamapumbu Harry, Simubali Limonty, Mudenda Twig, Thuma Philip E, Stevenson Jennifer C, Moss William J, Norris Douglas E
Am J Trop Med Hyg. 2022 Mar 28;106(5):1406-13. doi: 10.4269/ajtmh.21-0989.
Malaria transmission has declined substantially in Southern Province, Zambia, which is considered a low-transmission setting. The Zambian government introduced a reactive test-and-treat strategy to identify active zones of transmission and treat parasitemic residents. This study was conducted in the Choma District, Southern Province, Zambia, concurrently with an evaluation of this strategy to identify vectors responsible for sustaining transmission, and to identify entomological, spatial, and ecological risk factors associated with increased densities of mosquitoes. Anophelines were collected with CDC light traps indoors and near animal pens in index cases and neighboring households. Outdoor collections captured significantly more anophelines than indoor traps, and 10 different anopheline species were identified. Four species (Anopheles arabiensis, An. rufipes, An. squamosus, and An. coustani) were positive for Plasmodium falciparum circumsporozoite protein by ELISA, and 61% of these 26 anophelines were captured outdoors. Bloodmeal assays confirm plasticity in An. arabiensis foraging, feeding both on humans and animals, whereas An. rufipes, An. squamosus, and An. coustani were largely zoophilic and exophilic. Linear regression of count data for indoor traps revealed that households with at least one parasitemic resident by polymerase chain reaction testing was associated with higher female anopheline counts. This suggests that targeting households with parasitemic individuals for vector interventions may reduce indoor anopheline populations. However, many vectors species responsible for transmission may not be affected by indoor interventions because they are primarily exophilic and forage opportunistically. These data underscore the necessity for further evaluation of vector surveillance and control tools that are effective outdoors, in conjunction with current indoor-based interventions.
赞比亚南部省份的疟疾传播已大幅下降，该地区被视为低传播地区。赞比亚政府推出了一种反应性检测和治疗策略，以确定传播活跃区并治疗携带疟原虫的居民。本研究在赞比亚南部省份乔马区进行，同时对该策略进行评估，以确定维持传播的病媒，并确定与蚊子密度增加相关的昆虫学、空间和生态风险因素。在索引病例和邻近家庭的室内以及动物围栏附近，使用疾控中心诱蚊灯诱捕按蚊。室外采集捕获的按蚊明显多于室内诱捕器，共鉴定出10种不同的按蚊。通过酶联免疫吸附测定法，四种按蚊（阿拉伯按蚊、棕足按蚊、鳞斑按蚊和康氏按蚊）的恶性疟原虫环子孢子蛋白呈阳性，这26只按蚊中有61%是在室外捕获的。血餐检测证实了阿拉伯按蚊觅食的可塑性，它既吸食人类血液也吸食动物血液，而棕足按蚊、鳞斑按蚊和康氏按蚊主要偏好吸食动物血液且多在室外活动。室内诱捕器计数数据的线性回归显示，通过聚合酶链反应检测至少有一名携带疟原虫居民的家庭，其雌性按蚊数量较多。这表明针对有携带疟原虫个体的家庭进行病媒干预可能会减少室内按蚊数量。然而，许多负责传播的病媒物种可能不会受到室内干预的影响，因为它们主要在室外活动且觅食具有机会性。这些数据强调了有必要进一步评估在室外有效的病媒监测和控制工具，并结合当前基于室内的干预措施。
