Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, 5 Blvd Monivong, Phnom Penh 120 210, Phnom Penh, BP983, Cambodia.
UMR Unité des Virus Emergents, UVE: Aix-Marseille Univ-IRD 190-Inserm 1207-IHU 5 Méditerranée Infection, 13005, Marseille, France.
Malar J. 2024 Mar 12;23(1):75. doi: 10.1186/s12936-024-04890-6.
The Great Mekong Subregion has attained a major decline in malaria cases and fatalities over the last years, but residual transmission hotspots remain, supposedly fueled by forest workers and migrant populations. This study aimed to: (i) characterize the fine-scale mobility of forest-goers and understand links between their daily movement patterns and malaria transmission, using parasites detection via real time polymerase chain reaction (RT PCR) and the individual exposure to Anopheles bites by quantification of anti-Anopheles saliva antibodies via enzyme-linked immunosorbent assay; (ii) assess the concordance of questionnaires and Global Positioning System (GPS) data loggers for measuring mobility.
Two 28 day follow-ups during dry and rainy seasons, including a GPS tracking, questionnaires and health examinations, were performed on male forest goers representing the population at highest risk of infection. Their time spent in different land use categories and demographic data were analyzed in order to understand the risk factors driving malaria in the study area.
Malaria risk varied with village forest cover and at a resolution of only a few kilometers: participants from villages outside the forest had the highest malaria prevalence compared to participants from forest fringe's villages. The time spent in a specific environment did not modulate the risk of malaria, in particular the time spent in forest was not associated with a higher probability to detect malaria among forest-goers. The levels of antibody response to Anopheles salivary peptide among participants were significantly higher during the rainy season, in accordance with Anopheles mosquito density variation, but was not affected by sociodemographic and mobility factors. The agreement between GPS and self-reported data was only 61.9% in reporting each kind of visited environment.
In a context of residual malaria transmission which was mainly depicted by P. vivax asymptomatic infections, the implementation of questionnaires, GPS data-loggers and quantification of anti-saliva Anopheles antibodies on the high-risk group were not powerful enough to detect malaria risk factors associated with different mobility behaviours or time spent in various environments. The joint implementation of GPS trackers and questionnaires allowed to highlight the limitations of both methodologies and the benefits of using them together. New detection and follow-up strategies are still called for.
大湄公河次区域在过去几年中疟疾病例和死亡人数大幅下降，但仍存在残留的传播热点，据推测这些热点是由森林工人和移民人群引发的。本研究旨在：（i）描述森林工人的精细流动情况，并通过实时聚合酶链反应（RT-PCR）检测寄生虫和通过酶联免疫吸附试验（ELISA）量化抗疟唾液抗体来了解他们的日常活动模式与疟疾传播之间的联系；（ii）评估问卷和全球定位系统（GPS）数据记录器在测量流动性方面的一致性。
在旱季和雨季进行了两次为期 28 天的随访，包括 GPS 跟踪、问卷调查和健康检查，对象为感染风险最高的男性森林工人。分析了他们在不同土地利用类型中花费的时间和人口统计学数据，以了解导致该研究地区疟疾的风险因素。
疟疾风险随村庄森林覆盖率而变化，分辨率仅为数公里：与森林边缘村庄的参与者相比，来自非森林村庄的参与者疟疾患病率最高。在特定环境中花费的时间并不能调节疟疾的风险，特别是森林工人在森林中度过的时间与在森林工人中发现疟疾的可能性增加无关。参与者对疟蚊唾液肽的抗体反应水平在雨季明显较高，与疟蚊密度变化一致，但不受社会人口和流动性因素的影响。GPS 和自我报告数据在报告每种访问环境方面的一致性仅为 61.9%。
在主要由间日疟原虫无症状感染描述的残留疟疾传播背景下，对高危人群实施问卷、GPS 数据记录器和定量抗疟唾液抗体的方法不足以检测与不同流动性行为或在各种环境中花费的时间相关的疟疾风险因素。GPS 跟踪器和问卷调查的联合实施突出了这两种方法的局限性以及共同使用它们的好处。仍需要新的检测和随访策略。
