First detection of Anopheles stephensi Liston, 1901 (Diptera: culicidae) in Ethiopia using molecular and morphological approaches

Malaria is a major public health concern in Ethiopia. With the increase in malaria cases in the Somali Region of Ethiopia, understanding the distribution and identifying the species of malaria vectors is vital to public health. Here we report the first detection of Anopheles stephensi in Ethiopia, a malaria vector typically found in the Middle East, the Indian subcontinent, and China, but recently found in Djibouti. An entomological investigation was conducted during November to December 2016 in Kebri Dehar town of the Ethiopian Somali Regional State as ancillary work for Anopheles spp. surveillance. Mosquito larvae were collected from water reservoirs. Larvae were reared in the laboratory to the adult stage and identified morphologically. PCR and sequencing of cytochrome oxidase 1 (COI) and internal transcribed spacer 2 (ITS2) loci were performed. Basic Local Alignment Search Tool (BLAST) was used to compare sample sequences to sequences in the NCBI nucleotide database for species identification. To further analyze the relationship between the specimen we collected in Kebri Dehar and other Anopheles samples available in Genbank, phylogenetic analysis was performed using a maximum likelihood approach. Molecular and morphological results confirm specimens were An. stephensi. The closest high scoring hit was for all specimens was for the An. stephensi sequence. Independent phylogenetic analyses of COI and ITS2 sequences revealed in both cases strong bootstrap (100) support for our sequence forming a Glade with other An. stephensi sequences to the exclusion of any other species of Anopheles. In conclusion, Anopheles stephensi is present in Kebri Dehar town in Ethiopia. These findings highlight the need for additional research to examine the role of An. stephensi in malaria transmission in Ethiopia.