Relative Abundance of Malaria Vector and Malaria Transmission in Keffi, Nasarawa State, Nigeria from 2019 To 2024

This study assessed the relative abundance of malaria vectors and malaria transmission dynamics in Keffi, Nasarawa State, Nigeria, from 2019 to 2024. Malaria case data were obtained from the General Hospital, Keffi, while vector distribution and abundance data were sourced from the Presidential Malaria Initiative (PMI) Vector-Link database. Data were analysed using the chi-square test. A total of 53,077 Anopheles mosquitoes were collected during the study period. Anopheles gambiae sensu lato was the dominant vector, accounting for 83.2% of all collections, followed by Anopheles funestus (11.8%), while Anopheles nili was the least abundant (1.5%). Vector abundance varied significantly across the years (p < 0.05), with the highest collections recorded in 2024 (11,740) and 2021 (10,894), and the lowest in 2020 (3,418). Between 2019 and 2024, 6,650 patients were examined for malaria, of whom 4,084 tested positive, giving an overall prevalence of 61.4%. The highest malaria prevalence was recorded in 2023 (71.5%), followed by 2022 (69.0%), while the lowest prevalence occurred in 2020 (26.8%). Year-to-year variation in malaria prevalence was statistically significant (p < 0.05). A total of 15,272 Anopheles mosquitoes (An. Gambiae, An. Funestus, and An. Nili) were screened for Plasmodium species, with 2,013 found positive, yielding an overall sporozoite rate of 13.2%. Sporozoite rates differed significantly among vector species, with An. Gambiae showing the highest rate (14.6%), followed by An. Funestus (5.8%) and An. Nili (2.0%). Overall, malaria transmission in Keffi was primarily driven by Anopheles gambiae, with An. Funestus and An. Nili playing secondary roles. This study provides the first evidence of An. Nili contributing to malaria transmission in the area. The findings highlight the need for strengthened integrated vector management strategies, including indoor residual spraying, use of long-lasting insecticidal nets, and larval source management.