Elevated Plasmodium Sporozoite Infection Rates in Primary and Secondary Malaria Vectors in Anopheles stephensi-Infested Areas of Ethiopia

Abstract

Assessing bloodmeal sources and sporozoite infection rates in mosquito vectors is essential for understanding their role in malaria transmission. This study investigated these factors in Hawassa, Southern Ethiopia—an area recently invaded by Anopheles stephensi—through adult mosquito collections conducted between January and April 2023 using BG-Pro traps, CDC Light Traps, and Prokopack Aspirators. A total of 738 female Anopheles mosquitoes were collected, including An. arabiensis (72.9%), An. pharoensis (13.4%), An. stephensi (7.5%), and An. coustani (6.2%). Human Blood Index (HBI) values were 23.3% for An. arabiensis, 43.8% for An. pharoensis, 8.3% for An. stephensi, and 25.0% for An. coustani. Plasmodium infection was detected in 8% of An. arabiensis and 4.7% of An. pharoensis, while An. stephensi and An. coustani were uninfected. The findings highlight the presence of multiple competent malaria vectors, with significant infection rates observed in both primary and secondary species, underscoring the need to include secondary vectors in control and surveillance programs. The detection of An. stephensi alongside native vectors adds complexity to malaria control efforts, reinforcing the importance of continuous monitoring to understand the changing dynamics of vector populations and their roles in transmission.