Authors:

Notarides, Gregoris / Ergil, Ceyda - Researchers
Meletiou, Sotiris / Soganci, Mustafa – Technicians
Vasquez, Marlen I. / Tuzmen, Sukru– Scientists
Petric, Dusan – QA/QC Scientist
Orek, Yesim / Vasquez, Marlen I. - Coordinators

Highlights:

• Island-wide surveillance of West Nile Virus (WNV) in mosquitoes was established as a mosquito-borne pathogens surveillance model.
• Early detection of Aedes aegypti introduction at a site near the possible entry point.
• Three species, new for the island mosquito fauna, were detected both with morphological and molecular methods: Aedes pulcritarsis, Aedes aegypti, Culex laticinctus.
• Species detected only via molecular methods therefore further investigation is needed to confirm presence Culex quinquefasciatus.

With funding from the EU and implementation by UNDP in coordination with the OSASG-Cyprus, the Support Facility to the Technical Committees provided financial, conceptual, and operational support to the Technical Committee on Health to prepare and implement the Action "Mapping Risk for Vector-Borne  Diseases (ID-VRisk)", from September 2021 to October 2022.

Adult mosquito sampling was performed with both BG-Sentinel and EVS traps (Fig. 1) at biweekly intervals in 61 locations in Nicosia, Larnaca, Famagusta, Limassol, Kyrenia and Paphos. A total of 441 unique sampling sessions were completed, starting on 17-11-2021 and ending on 06-07-2022.   

An invasive mosquito transversal study was performed using 38 ovitraps at the same sampling interval. BG-Sentinel and EVS traps were baited by dry ice, while the BG-Sentinel operated with the addition of the chemical lure. Their placement in 24-hour sampling windows allowed the capture of species with different diurnal activity.

Figure 1: BG-Sentinel (left) and EVS (right) traps

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Two sampling strategies were used. The first sampling strategy clustered sampling stations around the areas with high human population density, known vector presence and where West Nile Virus (WNV) cases were previously observed (Fig. 2). The strategy focused on detecting WNV circulation in mosquitoes. The second sampling strategy was the wide area coverage strategy, where the traps were placed in a larger geographic area, covering 18 km x 18 km squares (Fig. 2). This was done to enhance the knowledge of species diversity and abundance in areas yet to be monitored and to provide a better understanding of mosquito species composition in general. For both sampling strategies, both BG-Sentinel and EVS traps were placed in 61 sampling sites once per month with sampling intervals of 2 weeks between wide area coverage and clustered sampling.

Figure 2: The island-wide sampling stations where BG-Sentinel and EVS traps were placed under the clustered and (left) and wide area coverage (right) sampling strategy.

Action utilized the surveillance network established through the implementation of the previous Action, "Identification and distribution of vectors of medical importance on the island of Cyprus (ID-VEC)" from September 2020 to September 2021, to:

• Complete the island-wide survey for native and invasive mosquito vectors throughout a dry and wet season in regions at higher risk for disease transmission (Aedes pulcritarsis, Aedes aegypti, Culex laticinctus)     

• Develop a vector-borne disease management plan using the model of West Nile Virus (WNV) surveillance.

• Integrate an early warning system in which mosquitoes will be used to predict possible outbreaks of WNV and, later, other mosquito-borne diseases.

• Enhance capacity building of Greek Cypriots and Turkish Cypriots to identify mosquitoes of medical significance and perform surveillance programs for detecting viruses.

• Increase public awareness of prevention and protection measures against mosquito bites and the significance of surveillance.

• Establish the fundamental pillars for integrated vector management (vector and disease surveillance, public outreach and education, quality control of suppression measures and research guidance).

On November 17th 2021, one male and one female of unknown species were caught in BG-Sentinel trap stations at Dromolaxia-Meneou in Larnaca (Fig. 3). Two weeks later, on December 3rd, one similar female was sampled. Specimens were in quite bad condition, and the local team was not confident in the preparation of the male genitalia. The morphological identification of the male genitalia revealed that the specimen belongs to Aedes aegypti. The finding was confirmed by molecular identification for the same male and two females in May 2022. 

The investigation of the way of the new introduction of Aedes aegypti is ongoing.

Figure 3: Area of the first detection Aedes aegypti in November 2021

During ID-VRisk Action, the reintroduction of one of the most dangerous invasive mosquito species, Aedes aegypti, was identified for the first time on the island at Larnaca, near the main point of entry. 

These findings indicate the necessity of maintaining island-wide surveillance as the only tool that can act as an early warning system to reduce the risk of an epidemic.

This project is funded by the European Union. It does not represent the views of the European Union, the United Nations Development Programme or the United Nations. This project is the result of contributions from various experts; the interpretations and opinions contained in it are solely those of the contributors.