Seroprevalence, Environmental Risk Factors, and Seasonal Patterns of Dengue Virus Infection in Nigeria: A Systematic Review and Meta-analysis (2014-2024)

BackgroundDengue virus (DENV) is an increasingly recognized cause of febrile illness in sub-Saharan Africa, yet its epidemiology in Nigeria remains incompletely characterized due to fragmented surveillance and diagnostic variability. We conducted a systematic review and meta-analysis to estimate marker-specific seroprevalence and to evaluate geographic variation, seasonal patterns, and environmental risk factors associated with DENV infection in Nigeria between 2014 and 2024. MethodsFollowing PRISMA guidelines, we searched PubMed, Scopus, Web of Science, EMBASE, Google Scholar, and African Index Medicus for studies reporting laboratory-confirmed dengue infection in Nigeria. Random-effects meta-analysis was used to estimate pooled prevalence and pooled odds ratios (ORs) with 95% confidence intervals (CIs). Between-study heterogeneity was quantified using the I{superscript 2} statistic. Subgroup analyses explored variation by diagnostic marker and geographic region. ResultsThirty-three studies met inclusion criteria. The pooled random-effects IgM seroprevalence was 20.9% (95% CI: 13.0-30.1; I{superscript 2} = 98.6%), while pooled IgG seroprevalence was 19.9% (95% CI: 11.6-29.7; I{superscript 2} = 97.7%). NS1 antigen positivity was 8.9% (95% CI: 2.2-19.4), and PCR-confirmed infection was 7.0% (95% CI: 1.2-16.2; I{superscript 2} = 25.8%). Significant differences were observed across diagnostic markers (p = 0.0002). Regional subgroup analysis demonstrated statistically significant geographic variation for both IgM (p = 0.0179) and IgG (p = 0.0030), with highest pooled prevalence observed in the Southeast and lowest in the Southsouth region. Environmental and behavioral exposures were strongly associated with seropositivity, including proximity to refuse dumpsites (OR = 9.39, 95% CI: 7.44-11.84), non-use of mosquito nets (OR = 8.70, 95% CI: 5.73-13.21), malaria positivity (OR = 5.54, 95% CI: 3.84-7.98), and open household water storage (OR = 2.18, 95% CI: 1.65-2.89). All four DENV serotypes were identified across reporting studies. Transmission intensity increased during rainy seasons. ConclusionsDengue virus transmission in Nigeria is widespread and geographically heterogeneous, with evidence of both recent and cumulative exposure. Strong associations with modifiable environmental and household-level factors underscore the importance of integrated vector control and improved diagnostic capacity. Enhanced surveillance and climate-informed public health strategies are essential to mitigate future outbreak risk. Author SummaryDengue is a mosquito-borne viral infection that is increasing globally but remains underrecognized in much of sub-Saharan Africa. In Nigeria, many febrile illnesses are presumed to be malaria, which can obscure the contribution of dengue virus infection. In addition, limited surveillance systems and inconsistent diagnostic testing have made it difficult to determine the true extent of dengue transmission. To address this gap, we conducted a systematic review and meta-analysis of studies published between 2014 and 2024 to evaluate patterns of dengue exposure, geographic variation, and environmental risk factors in Nigeria. We found evidence of both recent infection (IgM antibodies) and past exposure (IgG antibodies) across multiple regions of the country. Transmission intensity varied geographically, with higher levels observed in some regions, particularly in the Southeast, and lower levels in the Southsouth. Infection risk increased during the rainy season, consistent with enhanced mosquito breeding conditions. Living near refuse dumpsites, storing water in open containers, not using mosquito nets, and having malaria were all associated with higher odds of dengue infection, highlighting the importance of household and environmental conditions in shaping transmission risk. All four dengue virus serotypes were identified, indicating sustained viral circulation. These findings demonstrate that dengue virus infection is widespread in Nigeria and influenced by modifiable environmental and behavioral factors. Improving diagnostic capacity, strengthening routine surveillance, and implementing targeted vector control strategies are essential to reduce transmission and improve outbreak preparedness.