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.
What public health recommendations would you make based on your recent findings? How can regional and global cooperation be increased to improve local and global responses to the threat of diseases such as dengue fever?
Field surveillance for invasive mosquitoes and associated pathogens is crucial. In addition, robust diagnostic services must be available to swiftly identify cases and potential outbreaks. Imported cases of Dengue, Chikungunya and Zika infections have been previously reported from Turkey, which demonstrates an efficient diagnostic infrastructure. The cooperation among scientific and public health communities are significantly facilitated by internationally-funded efforts, such as European Union framework projects or specific bilateral agreements. These provide the supportive background for institutions such as ours, to continue our screening efforts and scientific research on the topic.
Which partnerships and technologies/innovations would you like to see developed to improve the surveillance and control of disease-carrying mosquitoes?
Field surveillance is hampered by the requirement of well-equipped laboratory facilities for screening and characterization. It takes considerable time until we can test our collection and find out about the mosquito species and locations where the pathogens are present. Currently, next generation sequencing and isothermal amplification-based assays have been advancing rapidly and started to provide equipment that can be employed in real-time, while the team is still in the field. This is a major step forward.
Is there a particular skill set in disease control which needs to be supported and developed to complement vector surveillance?
I have experienced that a considerable number of cases with rare or newly-emergent vector-borne infections can be missed during routine medical evaluation, especially when they present with mild symptoms. Therefore, increased awareness among physicians and general practitioners will help to identify individual infections. Considering the ever-changing epidemiological aspects of vector-borne viral diseases, we must all keep vigilant.
Link to full article:
Arboviral screening of invasive Aedes species in northeastern Turkey: West Nile virus circulation and detection of insect-only viruses Mustafa M. Akıner, Murat Öztürk, Aykut Buğra Başer, Filiz Günay, Sabri Hacıoğlu, Annika Brinkmann, Nergis Emanet, Bülent Alten, Aykut Özkul, Andreas Nitsche, Yvonne-Marie Linton, Koray Ergünay
Published: May 6, 2019https://doi.org/10.1371/journal.pntd.0007334