Territorial expansion of the invasive Aedes mosquito in Turkey

In recent decades, the highly invasive and disease-carrying Aedes mosquitoes have undergone a dramatic global expansion, establishing themselves in new regions worldwide. Dr. Koray Ergünay is a professor of medical microbiology at the Hacettepe University, Ankara, Turkey, where much of his research focuses on vector-borne viruses, assay development, vector surveillance, viral metagenomics and novel virus discovery. In this Infectious Thoughts interview, we speak to Dr. Ergünay about recent research on the establishment and re-establishment of invasive Aedes mosquitoes in Turkey and its potential consequences in terms of disease outbreak threats, public health and control strategies.

What have been recent trends in the establishment and re-establishment of the invasive Aedes mosquitoes in Turkey and neighbouring areas?

After decades of no detection, invasive Aedes mosquitoes could be identified continually in northern parts of the Anatolian peninsula, in regions neighboring the Black Sea. Current evidence suggest that these mosquitoes have been established in the region, a prerequisite for the introduction of pathogens. Similar findings have also been reported from various countries around the Black Sea.

Map of the locations used for mosquito collection in the study

(Red: countries/territories with Ae. aegypti and Ae. albopictus; Orange: countries/territories with Ae. albopictus). Blue dots represent sampling locations. The baseline map has been prepared using Natural Earth raster + vector map data in the public domain (URL: www.naturalearthdata.com. Accessed: April 2019), which is freely available for personal, educational, and commercial use. Current information on Aedesspecies were obtained from the European Centre for Disease Prevention and Control websites (https://ecdc.europa.eu/en/publications-data/aedes-aegypti-current-known-distribution-june-2018; https://ecdc.europa.eu/en/publications-data/aedes-albopictus-current-known-distribution-june-2018; Accessed: December 2018). https://doi.org/10.1371/journal.pntd.0007334.g001

Aedes aegypti and Aedes albopictus are vectors for several diseases including dengue fever and West Nile fever - which viral pathogens has your recent work identified? What is the public health risk for Turkey?

Currently, West Nile virus is known to circulate in Anatolia, which is also identified in our recent study. It appears as the single, most widely-distributed viral pathogen transmitted by mosquitoes in Turkey. Several individual cases have been reported, and an outbreak occurred in 2010. Following that, it became a mandatory notifiable disease and the National Public Health Agency started to provide centralized diagnostic services, which is still ongoing.

Dengue fever is the fastest growing mosquito-borne disease worldwide, threatening over half the world's population. What is the risk for Turkey?

It is hard to estimate precisely the risk for introduction of the agent and emergence as a human health threat, unless you have reliable, nationwide surveillance programs, which most of the countries, including Turkey, are lacking. However, given the consistent detection of the vector mosquitoes, it is safe to assume that the risk level for the introduction of Dengue is increased for Turkey. I must also emphasize that the pathogens themselves have not been detected indigenously so far.