Plasmodium falciparum and Dengue Fever Co-existence among Internally Displaced Populations (IDPs) in Cameroon: A Systematic Review

Background: Malaria and dengue fever increasingly overlap in sub-Saharan Africa. However, dengue remains under-reported in settings with high malaria transmission. IDPs may face heightened exposure to both infections due to overcrowding, environmental degradation, insecurity, and disrupted healthcare, but empirical evidence presents a significant gap.
Objective: To systematically synthesise empirical evidence on the epidemiology of Plasmodium falciparum, dengue virus, and malaria–dengue co-infection in Cameroon, with specific relevance to internally displaced populations.
Methods: A systematic review was carried out in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA 2020) guidelines. PubMed, Web of Science, Scopus, African Journals Online (AJOL), and Google Scholar were searched for studies published between January 2000 and March 2025. Eligible studies reported primary data on malaria, dengue, or co-infection in Cameroon or comparable displacement-affected African settings. Data were extracted and narratively synthesised.
Results: Thirty-two studies met the inclusion criteria, including twenty-one from Cameroon. Evidence confirms sustained dengue virus transmission and documented malaria–dengue co-infection among febrile patients. Reported co-infection prevalence ranged from approximately 3% to 10% among malaria-positive individuals. However, all Cameroonian studies were facility-based, and none focused explicitly on displaced populations. Despite environmental and entomological conditions in displacement settings being conducive to coexistence, epidemiological data are lacking.
Conclusion: There is clear evidence of malaria–dengue co-existence in Cameroon, yet a critical knowledge gap persists regarding IDP populations. Integrated surveillance improved diagnostic capacity, and targeted epidemiological research in humanitarian settings is urgently required.