Infectious Disease Epidemiology and Analytics, Institut Pasteur, Université Paris Cité, Paris, France.
Collège Doctoral, Sorbonne Université, Paris, France.
Malar J. 2024 Feb 15;23(1):49. doi: 10.1186/s12936-024-04859-5.
Over the last decades, the number of malaria cases has drastically reduced in Cambodia. As the overall prevalence of malaria in Cambodia declines, residual malaria transmission becomes increasingly fragmented over smaller remote regions. The aim of this study was to get an insight into the burden and epidemiological parameters of Plasmodium infections on the forest-fringe of Cambodia.
950 participants were recruited in the province of Mondulkiri in Cambodia and followed up from 2018 to 2020. Whole-blood samples were processed for Plasmodium spp. identification by PCR as well as for a serological immunoassay. A risk factor analysis was conducted for Plasmodium vivax PCR-detected infections throughout the study, and for P. vivax seropositivity at baseline. To evaluate the predictive effect of seropositivity at baseline on subsequent PCR-positivity, an analysis of P. vivax infection-free survival time stratified by serological status at baseline was performed.
Living inside the forest significantly increased the odds of P. vivax PCR-positivity by a factor of 18.3 (95% C.I. 7.7-43.5). Being a male adult was also a significant predictor of PCR-positivity. Similar risk profiles were identified for P. vivax seropositivity. The survival analysis showed that serological status at baseline significantly correlated with subsequent infection. Serology is most informative outside of the forest, where 94.0% (95% C.I. 90.7-97.4%) of seronegative individuals survived infection-free, compared to 32.4% (95% C.I.: 22.6-46.6%) of seropositive individuals.
This study justifies the need for serological diagnostic assays to target interventions in this region, particularly in demographic groups where a lot of risk heterogeneity persists, such as outside of the forest.
过去几十年来，柬埔寨的疟疾病例数量大幅减少。随着柬埔寨总体疟疾流行率的下降，残留的疟疾传播在较小的偏远地区变得越来越分散。本研究旨在深入了解柬埔寨森林边缘地区疟原虫感染的负担和流行病学参数。
2018 年至 2020 年期间，在柬埔寨蒙多基里省招募了 950 名参与者，并对其进行了随访。采集全血样本，通过 PCR 鉴定疟原虫种类，并进行血清学免疫分析。对整个研究期间检测到的间日疟原虫 PCR 感染和基线时的间日疟原虫血清阳性进行了危险因素分析。为评估基线时的血清阳性对随后 PCR 阳性的预测效果，对按基线时血清学状态分层的间日疟感染无进展生存时间进行了分析。
居住在森林内显著增加了间日疟原虫 PCR 阳性的几率，比值比为 18.3（95%置信区间为 7.7-43.5）。成年男性也是 PCR 阳性的显著预测因素。间日疟原虫血清阳性也存在类似的风险特征。生存分析表明，基线时的血清学状态与随后的感染显著相关。在森林外，血清学状态最具信息性，94.0%（95%置信区间为 90.7-97.4%）的血清阴性个体无感染存活，而 32.4%（95%置信区间为 22.6-46.6%）的血清阳性个体无感染存活。
本研究证明需要血清学诊断检测来针对该地区的干预措施，特别是在存在大量风险异质性的人群中，如在森林外。
