Analysis of the 24-h biting patterns and human exposures to malaria vectors in south-eastern Tanzania.

IF 3 2区 医学 Q1 PARASITOLOGY
Muwonge C Mukisa, Jibsam J Kassano, Yohana A Mwalugelo, Charles Ntege, Najat F Kahamba, Marceline F Finda, Betwel J Msugupakulya, Halfan S Ngowo, Fredros O Okumu
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引用次数: 0

Abstract

Background: Afrotropical malaria vectors are generally believed to bite nocturnally, leading to the predominant use of insecticide-treated nets (ITNs), which target indoor, nighttime-biting mosquitoes. This focus is reinforced by biases in entomological surveys, which largely overlook daytime mosquito activity. However, recent evidence challenges this paradigm, showing that Anopheles biting can extend way into the daytime, coinciding with human activities at dawn, daytime and evenings, suggesting a broader risk spectrum and potential protection gaps. We have therefore investigated the diurnal and nocturnal biting patterns of the malaria vectors Anopheles arabiensis and Anopheles funestus in south-eastern Tanzania, to better understand the scope of residual transmission and inform strategies for improved control.

Methods: Host-seeking mosquitoes were collected hourly using miniaturized double net traps, both indoors and outdoors over 24-h periods between June 2023 and February 2024. Concurrently, human activities indoors and outdoors were monitored half-hourly to correlate with mosquito collections. A structured questionnaire was used to assess household members' knowledge, perceptions and experiences regarding exposure to mosquito bites during both nighttime and daytime.

Results: Nocturnal biting by An. arabiensis peaked between 7 p.m. and 11 p.m. while that of An. funestus peaked later, between 1 a.m. and 3 a.m. Daytime biting accounted for 15.03% of An. arabiensis catches, with peaks around 7-11 a.m. and after 4 p.m., and for 14.15% of An. funestus catches, peaking around mid-mornings, from 10 a.m. to 12 p.m. Nighttime exposure to An. arabiensis was greater outdoors (54.5%), while daytime exposure was greater indoors (80.4%). For An. funestus, higher exposure was observed indoors, both at nighttime (57.1%) and daytime (69%). Plasmodium falciparum sporozoites were detected in both day-biting and night-biting An. arabiensis. Common daytime activities potentially exposing residents during peak biting hours included household chores, eating, sleeping (including due to sickness), resting in the shade or under verandas and playing (children). From evenings onwards, exposures coincided with resting, socializing before bedtime and playtime (children). Nearly all survey respondents (95.6%) reported experiencing daytime mosquito bites, but only 28% believed malaria was transmissible diurnally.

Conclusions: This study updates our understanding of malaria vector biting patterns in south-eastern Tanzania, revealing considerable additional risk in the mornings, daytime and evenings. Consequently, there may be more gaps in the protection provided by ITNs, which primarily target nocturnal mosquitoes, than previously thought. Complementary strategies are needed to holistically suppress vectors regardless of biting patterns (e.g. using larval source management) and to extend personal protection limits (e.g. using repellents). Additionally, community engagement and education on mosquito activity and protective measures could significantly reduce malaria transmission risk.

坦桑尼亚东南部疟疾病媒 24 小时叮咬模式和人类接触情况分析。
背景:人们普遍认为非洲热带疟疾病媒在夜间叮咬,因此主要使用驱虫蚊帐(ITNs),这种蚊帐主要针对室内夜间叮咬的蚊子。昆虫学调查中的偏差强化了这一观点,这些调查在很大程度上忽视了白天蚊子的活动。然而,最近的证据对这一模式提出了挑战,表明疟蚊叮咬可以延伸到白天,与人类在黎明、白天和晚上的活动相吻合,这表明存在更广泛的风险范围和潜在的保护缺口。因此,我们在坦桑尼亚东南部调查了疟疾病媒阿拉伯按蚊和按蚊的昼间和夜间叮咬模式,以更好地了解残余传播的范围,并为改进控制策略提供信息。方法:在 2023 年 6 月至 2024 年 2 月期间的 24 小时内,使用微型双网诱捕器在室内和室外每小时收集寻找宿主的蚊子。同时,每半小时监测一次室内和室外的人类活动,以便与蚊子收集相关联。采用结构化问卷评估家庭成员对夜间和白天蚊虫叮咬的了解、看法和经验:结果:阿拉伯疟蚊夜间叮咬的高峰期在晚上 7 点至 11 点之间,而疟原虫叮咬的高峰期较晚,在凌晨 1 点至 3 点之间、夜间在室外接触阿拉伯疟蚊的比例较高(54.5%),而白天在室内接触的比例较高(80.4%)。至于疟原虫,夜间(57.1%)和白天(69%)在室内的接触率都较高。在日咬和夜咬的阿拉伯疟蚊中都检测到恶性疟原虫孢子虫。在叮咬高峰期,居民日间可能接触到恶性疟原虫孢子虫的常见活动包括做家务、进食、睡觉(包括生病)、在树荫下或阳台下休息以及玩耍(儿童)。从晚上开始,接触时间与休息、睡前社交和玩耍时间(儿童)相吻合。几乎所有调查对象(95.6%)都表示白天被蚊子叮咬过,但只有 28% 的人认为疟疾可在昼间传播:这项研究更新了我们对坦桑尼亚东南部疟疾病媒叮咬模式的认识,揭示了早晨、白天和晚上的额外风险。因此,主要针对夜间蚊子的驱虫蚊帐所提供的保护可能比以前认为的存在更多的漏洞。需要采取补充战略,以全面抑制病媒,而不论其叮咬模式如何(如使用幼虫源管理),并扩大个人保护范围(如使用驱蚊剂)。此外,社区参与和关于蚊子活动及防护措施的教育可大大降低疟疾传播风险。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Parasites & Vectors
Parasites & Vectors 医学-寄生虫学
CiteScore
6.30
自引率
9.40%
发文量
433
审稿时长
1.4 months
期刊介绍: Parasites & Vectors is an open access, peer-reviewed online journal dealing with the biology of parasites, parasitic diseases, intermediate hosts, vectors and vector-borne pathogens. Manuscripts published in this journal will be available to all worldwide, with no barriers to access, immediately following acceptance. However, authors retain the copyright of their material and may use it, or distribute it, as they wish. Manuscripts on all aspects of the basic and applied biology of parasites, intermediate hosts, vectors and vector-borne pathogens will be considered. In addition to the traditional and well-established areas of science in these fields, we also aim to provide a vehicle for publication of the rapidly developing resources and technology in parasite, intermediate host and vector genomics and their impacts on biological research. We are able to publish large datasets and extensive results, frequently associated with genomic and post-genomic technologies, which are not readily accommodated in traditional journals. Manuscripts addressing broader issues, for example economics, social sciences and global climate change in relation to parasites, vectors and disease control, are also welcomed.
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