Soumare Harouna M, Blanken Sara Lynn, Ahmad Abdullahi, Ooko Michael, Gaye Pa Modou, Jadama Lamin, Camara Muhammed M, Jawara Ebrima A, Lanke Kjerstin, Njie Amie Kolleh, Mendy Michael, Etoketim Blessed, Camara Lamin, Ndiath Mamadou O, Conteh Bakary, Muhammed Nuredin, Soremekun Seyi, Nyassi Abdoullah, Erhart Annette, Drakeley Chris, Bousema Teun, D'Alessandro Umberto, Moreno Marta
Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia; Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands.
Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands.
J Infect. 2025 Jul;91(1):106507. doi: 10.1016/j.jinf.2025.106507. Epub 2025 May 20.
In The Gambia, the scale-up of malaria control interventions in the past decades resulted in a substantial decrease of the malaria burden. However, low levels of malaria transmission persist.
We conducted an observational cohort study in eastern Gambia to better understand the relative contribution of symptomatic and asymptomatic malaria infections to the infectious reservoir. Parasite and gametocyte carriage were determined by molecular methods. Infectiousness to mosquitoes was assessed by mosquito membrane feeding assays on a subset of symptomatic and asymptomatic individuals identified by passive case detection and community surveys.
Incidence of clinical malaria was 1.46 episodes/100 person-months. Prevalence of malaria infection as determined by PCR in community surveys was 10.5%. Among asymptomatic malaria-infected individuals, total parasite density was positively associated with gametocyte density (β = 0.40; P < .0001). Mosquito infection rates in membrane feeding experiments were positively associated with gametocyte density (β = 2.81; P < 0.0001). More than 84% of mosquito infections occurred in asymptomatic individuals with patent infections, with the highest contribution from older children (40.3%), and adolescents and adults (45.5%). Clinical malaria cases identified by passive case detection were responsible for only 1% of mosquito infections; if the definition of clinical malaria included infected individuals identified by community surveys with a history of fever in the preceding week, the contribution of clinical cases to mosquito infections increased to 16%.
In eastern Gambia, malaria transmission is maintained by asymptomatic malaria-infected individuals, mostly adults, adolescents and school-age children, while clinical cases are comparatively less important for transmission.
在冈比亚，过去几十年疟疾控制干预措施的扩大实施使疟疾负担大幅下降。然而，低水平的疟疾传播仍然存在。
我们在冈比亚东部进行了一项观察性队列研究，以更好地了解有症状和无症状疟疾感染对感染源的相对贡献。通过分子方法确定寄生虫和配子体携带情况。通过对被动病例检测和社区调查确定的一部分有症状和无症状个体进行蚊媒膜饲试验，评估对蚊子的传染性。
临床疟疾发病率为1.46例/100人月。社区调查中通过PCR确定的疟疾感染患病率为10.5%。在无症状疟疾感染个体中，总寄生虫密度与配子体密度呈正相关（β = 0.40；P <.0001）。膜饲试验中的蚊子感染率与配子体密度呈正相关（β = 2.81；P < 0.0001）。超过84%的蚊子感染发生在有显性感染的无症状个体中，其中年龄较大儿童的贡献最大（40.3%），青少年和成年人的贡献为45.5%。被动病例检测确定的临床疟疾病例仅占蚊子感染的1%；如果临床疟疾的定义包括社区调查中确定的在前一周有发热史的感染个体，临床病例对蚊子感染的贡献将增加到16%。
在冈比亚东部，疟疾传播由无症状疟疾感染个体维持，主要是成年人、青少年和学龄儿童，而临床病例对传播的重要性相对较小。
