The Phylodynamic and Spread of the Invasive Asian Malaria Vectors, Anopheles stephensi, in Sudan

Simple Summary Climate change increases the suitability of some environments for the establishment of newly introduced insects and is a major driver for the spread of mosquitoes that transmit diseases. Anopheles stephensi is a disease vector mosquito that transmits malaria and is naturally endemic in Asia. This vector newly emerged in Africa (first report from Djibouti in 2012), where annual malaria infections and deaths are the highest worldwide. This mosquito has different ecology and behavior from previously known malaria vectors in Africa, which makes control difficult for local under-resourced health systems. Considering the capacity of this vector to transmit at least two malaria-causing parasites (Plasmodium falciparum and Plasmodium vivax), we investigated its distribution and population structure in Sudan and assessed the potential risk of its further spread into neighboring countries. Using morphological and genomic sequencing techniques, we confirmed the presence of Anopheles stephensi along the borders of six countries previously assumed as free, including Chad, Egypt, Eritrea, Libya, Republic of Central Africa, and South Sudan. African countries need to enhance vector surveillance and control services and utilize genomics tools for tracking the dynamics of invasive disease vectors. Anopheles stephensi is an invasive Asian malaria vector that initially emerged in Africa in 2012 and was reported in Sudan in 2019. We investigated the distribution and population structure of An. stephensi throughout Sudan by using sequencing and molecular tools. We confirmed the presence of An. stephensi in eight border-states, identifying both natural and human-made breeding sites. Our analysis revealed the presence of 20 haplotypes with different distributions per state. This study revealed a countrywide spread of An. stephensi in Sudan, with confirmed presence in borders states with Chad, Egypt, Eritrea, Ethiopia, Libya, Republic of Central Africa, and South Sudan. Detection of An. stephensi at points of entry with these countries, particularly Chad, Libya, and South Sudan, indicates the rapid previously undetected spread of this invasive vector. Our phylogenetic and haplotype analysis suggested local establishment and evolutionary adaptation of the vector to different ecological and environmental conditions in Sudan. Urgent engagement of the global community is essential to control and prevent further spread into Africa.

Automated summary

This study investigated the distribution and population structure of Anopheles stephensi in Sudan, confirming its presence in eight border states with neighboring countries. Analysis revealed the presence of 20 haplotypes with differing distributions across Sudan. Detection of An. stephensi at points of entry with Chad, Egypt, Eritrea, Ethiopia, Libya, Republic of Central Africa, and South Sudan indicates the rapid spread of this invasive vector in Africa. The study suggests local establishment and evolutionary adaptation of An. stephensi to different ecological and environmental conditions in Sudan, emphasizing the urgent need for global engagement to control and prevent further spread.