Seasonal Dynamics of Human IgG Antibody Responses to Aedes Nterm-34kDa Peptide as a Biomarker of Alphavirus and Flavivirus Transmission in Northern Tanzania

BackgroundContinued expansion of arboviral diseases poses a serious threat to public health systems. The use of biomarkers for mosquito exposure, such as antibodies against the Aedes Nterm-34 kDa peptide, serves as a proxy for assessing the risk of Aedes-borne diseases. This study aimed to evaluate whether IgG antibodies against the Nterm-34 kDa peptide are associated with the level of human exposure to Aedes mosquito bites and the risk of flavivirus and alphavirus infections. MethodsThree longitudinal surveys were conducted during the rainy, dry, and short rainy seasons in three villages in Bondo, Tanga. The study included individuals aged between 2 to 70 years. A questionnaire was administered to participants to collect information on socio-demographic factors, housing conditions, surrounding environmental features, and mosquito bite prevention measures. In parallel, intravenous blood was collected from each participant for virus detection using RT-qPCR and for quantification of IgG antibodies against the Aedes Nterm-34kDa peptide using an ELISA assay ResultsA total of 362 participants were enrolled, with a mean age of 28.3 {+/-} 23.1 years. Alphavirus positivity peaked in the rainy season 19 (5.2%), with lower prevalence during dry 4 (1.1%) and short rainy 9 (2.5%) seasons, whereas flavivirus positivity was lower overall 11 (3.0%) rainy, 3 (0.8%) dry, 5 (1.4%) short rainy). IgG antibody levels against the Aedes 34 kDa peptide were significantly higher in PCR-positive. The level of IgG antibody response to the Nterm-34kDa peptide exhibited seasonal variation, with significantly higher values observed during the rainy season compared to the dry season (Mann-Whitney U test, p < 0.0001). IgG seropositivity was significantly associated with proximity to vegetation (p < 0.001), presence of garbage pits (p = 0.005), and recent travel history (p = 0.018), whereas demographic and housing factors showed no significant associations. Participants positive for dengue demonstrated higher levels of anti-salivary IgG compared with dengue-negative participants (p = 0.02; non-parametric Mann-Whitney test). ConclusionsThis study reveals distinct seasonal dynamics in human IgG antibody responses to the Aedes Nterm-34kDa salivary peptide, reflecting the seasonal transmission patterns of Alphavirus and Flavivirus in northern Tanzania. Elevated seropositivity during the rainy season aligns with increased vector exposure driven by environmental factors near human dwellings. The findings underscore the potential of the Nterm-34kDa peptide as a biomarker for arboviral transmission monitoring and highlight the importance of targeted vector control strategies considering seasonal and microenvironmental variations to mitigate Aedes-borne viral infections in the region.