Spatio-temporal occurrence and habitat characteristics of Aedes aegypti (Diptera: Culicidae) larvae in Southern Afar region, Ethiopia.

Background: Describing spatio-temporal occurrence and habitat characteristics of Aedes mosquito larvae is crucial for the control of Aedes borne viral diseases. This study assessed spatio-temporal abundance and habitat characteristics of Aedes larvae in the Southern Afar Region, Ethiopia.

Methods: Immature mosquitoes were surveyed in Awash Sebat, Awash Arba, and Werer towns of the Southern Afar Region once per month from May 2022 to April 2023. Larvae and pupae surveys were carried out along the available water-holding containers. The collected larvae/pupae were reared to adults and identified by  species/genus morphologically. The physical and chemical properties of the habitats were also characterized.

Results: A total of 9099 Aedes larvae/pupae were collected, of which 53.6% (4875) were from Awash Sebat, 29.5% (2687) from Awash Arba and 16.9% (1537) from Werer. Water-holding tyres harboured the highest number of Aedes larvae/pupae followed by water-storage drums. All the Aedes larvae/pupae reared to adults were morphologically identified as Aedes aegypti. The overall Container Index was 47.28%, House Index 18.19%, Breteau Index 59.94% and Pupal Index 171.94. Significant positive relations were observed in the occurrences of Ae. aegypti larvae/pupae with water-holding tyre (AOR = 15.89, CI = 3.55-71.09, p < 0.001), water storage drums (AOR = 19.84, CI = 4.64-84.89, p < 0.001), domestic habitat (AOR = 3.76, CI = 1.27-11.12, p = 0.017), and significant negative relations were observed with Ae. aegypti larvae/pupae occurrence and tap water source (AOR = 0.08, CI = 0.02-0.31, p = 0.001). Ae. aegypti larvae/pupae densities showed positive relations with dissolved oxygen (β = 0.523, p < 0.001) and total hardness (β = 0.475, p = 0.034) of water.

Conclusions: Diverse types of artificial water-holding containers were positive for Ae. aegypti larvae/pupae. Ae. aegypti larvae/pupae were abundant in used water-holding tyres, water storage drums, and cement tanks in Awash Sebat, Awash Arba, and Werer towns. This could  put the residents of the towns at high risk of infections with Ae. aegypti transmitted viral diseases such as chikungunya and dengue outbreaks. Thus, we recommend artificial water-holding container management as a strategy to control Ae. aegypti and hence the arboviral diseases transmission.