McIver David J, Vajda Elodie A, Doum Dyna, Daniel Nicholas W, Quan Molly, Lovin Diane D, Cunningham Joanne M, Sovannaroth Siv, Tatarsky Allison, Lobo Neil F
Malaria Elimination Initiative, Institute for Global Health Sciences, University of California, 550 16th Street, San Francisco, CA, 94158, USA.
Swiss Tropical and Public Health Institute, Socinstrasse 57, P. O. Box, CH-4002, Basel, Switzerland.
Malar J. 2025 Mar 24;24(1):96. doi: 10.1186/s12936-025-05304-x.
Forest-exposed populations remain the last significant, and most difficult to access, high-risk populations for malaria in Cambodia. Despite the availability of long-lasting insecticidal nets (LLINs) and/or hammock nets (LLIHNs), continued malaria transmission indicates gaps in protection. This study aimed to identify these gaps among forest-exposed individuals in Plasmodium falciparum hotspots in two provinces in Cambodia, using entomological assessments and human behaviour observations (HBOs).
Anopheles bionomic traits were characterized using Human Landing Catches (HLCs) in a village setting in Mondulkiri province, and in both village and forest settings in Kampong Speu province, Cambodia. Mosquitoes were collected from 17h00 to 07h00 over 540 collection nights. Human behaviour observations (HBOs) focused on monitoring activities near HLC sites and recording the use of LLINs/LLIHNs or Project BITE's bite prevention tools: a volatile pyrethroid spatial repellent (VPSR), topical repellent (TR), and insecticide-treated clothing (ITC). Data on mosquito landing pressure and human behaviours were integrated to generate the HBO-adjusted Human Landing Rate (HBO-adjusted HLR).
A total of 5,985 Anopheles mosquitoes were collected, with 608 (10%) identified molecularly to species-level. Seventeen Anopheles species were identified, including a likely novel species from the Leucosphyrus Subgroup, which was the predominant species characterized. The HBO-adjusted HLR was found to be greatest during the early evening hours, when people were outdoors awake, followed by when people were sleeping indoors without a net. Relatively few people were observed using, or correctly using, the new bite prevention tools intended for protection in the forest.
This study demonstrates the importance of understanding spatial and temporal human exposure to mosquito bites, in the presence of proven vector control tools (LLINs, LLIHNs) and newly introduced bite prevention tools (VPSRs, ITCs, and TRs). To help achieve malaria elimination, human behaviour data on intervention use and behaviour patterns should be evaluated and integrated with entomological data towards identifying and quantifying protection conferred by current interventions, as well as remaining gaps in protection. This information supports the selection of appropriate interventions, which supplement rather than replace existing tools, to target existing gaps in protection.
在柬埔寨，接触森林的人群仍然是最后一批数量可观且最难接触到的疟疾高危人群。尽管有长效驱虫蚊帐（LLINs）和/或吊床蚊帐（LLIHNs），但疟疾的持续传播表明在保护方面存在差距。本研究旨在通过昆虫学评估和人类行为观察（HBOs），确定柬埔寨两个省份恶性疟原虫热点地区接触森林人群中的这些差距。
在蒙多基里省的一个村庄环境中，以及柬埔寨磅士卑省的村庄和森林环境中，使用人饵诱捕法（HLCs）对按蚊的生物学特性进行了表征。在540个采集夜晚的17:00至07:00收集蚊子。人类行为观察（HBOs）侧重于监测HLC站点附近的活动，并记录LLINs/LLIHNs或项目BITE的防叮咬工具的使用情况：挥发性拟除虫菊酯空间驱避剂（VPSR）、局部驱避剂（TR）和经杀虫剂处理的衣物（ITC）。整合蚊子叮咬压力和人类行为数据，以生成经HBO调整的人饵诱捕率（经HBO调整的HLR）。
共收集到5985只按蚊，其中608只（10%）通过分子鉴定到物种水平。鉴定出17种按蚊，包括一种可能来自白环亚组的新物种，该物种是主要特征物种。发现经HBO调整的HLR在傍晚人们在户外清醒时最高，其次是人们在室内无蚊帐睡眠时。观察到使用或正确使用旨在在森林中提供保护的新型防叮咬工具的人相对较少。
本研究证明了在有经过验证的病媒控制工具（LLINs、LLIHNs）和新引入的防叮咬工具（VPSRs、ITCs和TRs）的情况下，了解人类在空间和时间上接触蚊子叮咬的重要性。为了帮助实现疟疾消除，应评估关于干预措施使用和行为模式的人类行为数据，并将其与昆虫学数据相结合，以确定和量化当前干预措施提供的保护以及保护方面仍然存在的差距。这些信息有助于选择适当的干预措施，以补充而非取代现有工具，针对现有的保护差距。
