Study Sites Characteristics (May-Sep 2023).

Despite global malaria control efforts, the disease caused 263 million cases and 597,000 deaths in 2023. While Plasmodium falciparum accounts for most cases in Africa, non-falciparum species, such as P. ovale spp. and P. vivax, can cause relapse infections and are increasingly recognized as significant contributors to human disease. In particular, the highlands of West Cameroon have previously been reported to have high P. vivax infection rates. This study presents preliminary results from the Relapsing Malaria in Africa (ReMA) study, conducted in Dschang, Cameroon, to assess the prevalence and epidemiology of P. vivax and P. ovale spp. A cross-sectional survey of 3,661 participants from 871 households across seven health areas identified a low prevalence of P. vivax (0.1%) and P. ovale spp. (0.64%) using quantitative real time PCR (qPCR), while P. falciparum remained prevalent at 8.1%. Co-infections of P. ovale spp. with P. falciparum were observed in 23.1% of P. ovale spp. cases. While gametocytemia was common among falciparum infections, leveraging a new ovale gametocyte assay, we found that gametocytemia was uncommon among the qPCR- positive ovale infections. Spatial analysis found P. vivax and P. ovale spp. infections concentrated in Penka-Michel and Baleveng, the former having higher Anopheles spp. abundance than other areas assessed. Risk factor analysis revealed children and those with recent domestic travel had higher odds of P. falciparum infection, but no significant associations were found for P. ovale spp. infections. Entomological surveys confirmed high densities of Anopheles gambiae sensu lato (s.l.) and An. funestus (s.l.), with significantly higher human landing capture rates for An. gambiae s.l compared to other mosquito species. While these findings suggest that the malaria species which cause relapse are not as widespread as previously thought in West Cameroon, understanding factors driving their persistent transmission, especially without prevalent gametocytemia, will be important for disease control.尽管全球已开展疟疾防控工作，但2023年该疾病仍造成2.63亿例发病与59.7万例死亡。恶性疟原虫（Plasmodium falciparum）是非洲多数疟疾病例的致病原，但卵形疟原虫群（P. ovale spp.）、间日疟原虫（P. vivax）等非恶性疟原虫物种可引发复发感染，且日益被视为人类疟疾的重要致病因素。喀麦隆西部高地此前已有报道显示间日疟原虫感染率较高。本研究呈现了在喀麦隆尚古（Dschang）开展的非洲复发疟疾（Relapsing Malaria in Africa, ReMA）初步研究结果，旨在评估间日疟原虫与卵形疟原虫群的流行率及流行病学特征。研究人员对7个卫生区域内871户家庭的3661名参与者开展横断面调查，通过实时定量聚合酶链反应（quantitative real time PCR, qPCR）检测发现，间日疟原虫流行率为0.1%，卵形疟原虫群流行率为0.64%，而恶性疟原虫流行率仍达8.1%。在卵形疟原虫群感染病例中，23.1%合并感染了恶性疟原虫。尽管配子体血症在恶性疟原虫感染中较为常见，但借助全新的卵形疟原虫配子体检测手段，研究人员发现配子体血症在qPCR阳性的卵形疟原虫感染中并不常见。空间分析显示，间日疟原虫与卵形疟原虫群感染集中分布于彭卡-米歇尔（Penka-Michel）与巴莱文格（Baleveng）两个区域，其中彭卡-米歇尔的按蚊（Anopheles spp.）种群密度高于其他调研区域。危险因素分析表明，儿童及近期有国内旅行史的人群感染恶性疟原虫的风险更高，但未发现卵形疟原虫群感染与相关危险因素存在显著关联。昆虫学调查证实，冈比亚按蚊复合群（Anopheles gambiae sensu lato, s.l.）与致命按蚊复合群（An. funestus s.l.）种群密度较高，且冈比亚按蚊复合群的人类诱捕捕获率显著高于其他蚊种。尽管上述结果表明，引发复发型疟疾的疟原虫物种在喀麦隆西部的传播范围并未如此前预想的那般广泛，但明确驱动其持续传播的相关因素——尤其是在配子体血症并不普遍的情况下——对于疟疾防控工作仍具有重要意义。