Chikungunya and Dengue Risk Assessment in Greece

Objective: The aims of the study were:

(1) To assess the mutated CHIKV E1-A226V and DENV II infection and dissemination rates of an Ae. albopictus population established in Athens (Greece)

(2) To assess the risk of outbreaks in four Greek localities based on Ae. albopictus population density whose estimate was based on the number of eggs laid in ovitraps.

Methods: Under laboratory conditions females were offered blood meal infected with the CHIKV titer of 1X106 TCID 50/mL and DENV II titer of 1.76 X106 TCID 50/mL; at day 11 after oral infection, females were sacrificed, legs were removed and processed for PCR analysis to assess the presence of viral replicates. In order to evaluate the risk of outbreak of CHIKV and DENV II, a pilot monitoring program was started in three Greek localities and in Chania (Crete), to estimate the adult female population density on the base of the number of eggs in the ovitraps.

Results: We proved the vector competence of the Greek Ae. albopictus strain for E1-A226V mutated CHIKV and DENV II. Combining the data on the vector competence with those on the female population density, based on the egg density data, the estimated risk of outbreak was relatively low but not negligible.

Conclusion: As the vector competence estimated under laboratory conditions was obtained by offering females moderately low initial virus titers, it can be expected a higher vector competence in the field. This consideration, together with a possible increase of the mosquito population due to the global warming effects, make the quantitative ovitrap-based monitoring a necessary and useful tool to estimate the risk of outbreaks.