Entomological Transmission Risk of Arboviral Diseases: Aedes Mosquito Infestation in Urban and Semi-Urban Areas of Ibadan, Nigeria

Background: Arboviral diseases, such as dengue, Zika, chikungunya, and yellow fever, are significant public health threats, primarily transmitted by Aedes mosquitoes. Understanding vector infestation levels and breeding site preferences is essential to develop effective control strategies. This study assesses the entomological transmission risk of arboviral diseases by evaluating Aedes mosquito distribution, abundance, and breeding habitats in urban and semi-urban areas of Ibadan, Nigeria.

Methods: A cross-sectional entomological survey was conducted in 5,223 households, with 36,779 water-holding containers examined for Aedes mosquito breeding. Standard infestation indices—the House Index (HI), Container Index (CI), and Breteau Index (BI)—were calculated. The Breeding Preference Ratio (BPR) was used to determine habitat suitability. Data analysis included statistical comparisons of larval and pupal densities between study locations.

Results: This study revealed high infestation levels, with HI values of 71.2% (semi-urban) and 75.2% (urban), CI values of 79.0% (semi-urban) and 67.3% (urban), and BI values of 579.9% and 443.8%, respectively. These indices exceed World Health Organization thresholds, indicating high transmission risk. Artificial containers, particularly tyres, plastics, and vehicle parts, were dominant breeding sites, with BPR values exceeding 1.0 for key habitats. A total of 104,989 larvae and 43,002 pupae were recorded in semi-urban areas, while 78,016 larvae and 34,652 pupae were found in urban locations. Semi-urban areas had higher larval densities, whereas urban sites exhibited greater pupal densities, suggesting differential transmission dynamics.

Conclusion: Targeted vector control interventions, including environmental sanitation and larval source reduction, are essential to mitigate arboviral disease transmission risks in Ibadan and similar endemic regions.

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