Spatial distribution and population structure of the invasive Anopheles stephensi in Kenya from 2022 to 2024
Jeanne N. Samake, Duncan K. Athinya, Sylvia Milanoi, Edith Ramaita, Margaret Muchoki, Seline Omondi, Bernard Abong’o, Damaris Matoke-Muhia, Charles Mbogo, Kibor Keitany, Wolfgang R Mukabana, Florence Oyieke, Mildred Shieshia, Monica Mburu, Sheila B. Ogoma, Elizabeth Nyawira, Celestine Wekesa, Brian Bartilol, Martin Rono, Marta F. Maia, Wendy Prudhomme O’Meara, Samuel Kahindi, Cristina Rafferty, Jonathan Schultz, Julie Gutman, John E. Gimnig, Sarah Zohdy, Eric Ochomo
Abstract
This study analyzes the distribution, genetic diversity, and spread of Anopheles stephensi in Kenya following initial detection in December 2022. A total of 114 larval and 33 adult An. stephensi samples were confirmed in 7 of 18 surveyed counties majorly along transportation routes. Genetic analyses revealed three distinct genetic compositions with different levels of genetic diversity, suggesting multiple introductions into the country. The genetic composition of mosquitoes in most counties resembled southern Ethiopian populations, while those from Turkana showed a unique haplotype. A species distribution model predicts a more extensive range than currently observed, with low precipitation and minimal seasonal temperature variations as key factors influencing distribution. Challenges in adult sampling were noted, with larval sampling revealing co-occurrence with native Anopheles species. The findings have implications for surveillance and control strategies, emphasizing the need for continued monitoring, refined sampling techniques to inform bionomics, and cross-border collaboration.