Altitudinal cross-sectional study of the sand fly fauna of the highlands of Tigray Region, northern Ethiopia.

BACKGROUND

Cutaneous leishmaniasis (CL), caused by Leishmania aethiopica and transmitted by Phlebotomus longipes, is endemic in northern Ethiopia. However, sand fly fauna is poorly documented in the northern Tigray region. High-altitude CL cases have also been observed, but their local acquisition is uncertain. To identify the faunal composition, their geographical and altitudinal distribution, cross-sectional surveys were conducted in ten villages (average altitude range: 2411 - 3186 meters) with confirmed CL cases across four endemic districts of the region. A total of 170 light trap-nights and 1700 sticky trap-nights of sand fly collections were made.

RESULTS

Totally, 1477 sand flies (52% males & 48% females) comprising five species of Phlebotomus (38%) and six species of Sergentomyia (62%) were identified morphologically. The Phlebotomus species included Phlebotomus longipes (73%), one confirmed (Phlebotomus sergenti (6%), and two potential vectors of Leishmania tropica: Phlebotomus arabicus (18%), and Phlebotomus guggisbergi (2%); the latter is a new record for Ethiopia. Phlebotomus longipes is widely distributed and predominated in caves (43%), animal sheds (28%), and bedrooms (15%). Phlebotomus longipes and three Sergentomyia species were found at average elevations reaching 3186 meters, setting a new altitude record for Ethiopia. Phlebotomus arabicus was also found up to 3045 meters in hyrax habitats.

CONCLUSION

The risk of CL in Tigray reaches up to 3200 meters. Phlebotomus longipes habitats suggest the potential for domestic and peri-domestic transmission of CL. Further research is needed to determine if the new high-altitude presence of the sand fly species is due to climate change or other factors.