Risk assessment for chikungunya in the EU continental and overseas countries, territories and departments
The risk of transmission of chikungunya virus is the result of simultaneous presence of the virus, the competent mosquitoes and susceptible human hosts, and contact between these three entities.
Risk assessment for the European Union continental
The risk of chikungunya fever spreading in EU is high due to possible importation through infected travellers, presence of the competent mosquito vectors in many countries (particularly around the Mediterranean coast) and population susceptibility. The presence of the vector and the introduction of the virus are necessary conditions for having local transmission.
Chikungunya virus is currently not endemic in continental Europe. Only one large outbreak was reported in northern Italy in 2007 and limited autochthonous cases were reported in France in 2010 and 2014. Otherwise all reported cases are imported.
The risk of importation of infected mosquitoes seems insignificant compared to the risk of infection related to travel to endemic areas. Most aircrafts arriving from tropical regions are disinfected and Aedes aegypti has rarely been found on aircraft .
The highest likelihood for transmission in Europe is linked to importation of virus by infected travellers to areas with competent vectors (Aedes albopictus on mainland Europe and Aedes aegypti in Madeira). Considering the high frequency of travellers between high incidence areas in the world and the European Union and the past experiences in Italy and France, the risk of more chikungunya fever outbreaks in continental Europe is not unlikely.
Travellers returning from outbreak areas should seek medical care if presenting with chikungunya fever compatible symptoms and apply personal protection measures to avoid mosquito bites. Such measures will reduce the risk of chikungunya introduction in the European mosquito population and prevent local transmission during the summer season.
Vigilance must be maintained, as the risk of chikungunya fever outbreaks in continental Europe is definitely present in regions with well-established Aedes albopictus and/or Aedes aegypti populations. With the further spread of the competent vector in Europe, so far impossible to stop, more and more regions are likely to become at risk.
Risk assessment for the overseas countries, territories and EU outermost regions
While chikungunya fever outbreaks occur in the overseas countries, territories and departments, there is no evidence yet that the disease is established as endemic over there. Outbreaks are so far unpredictable and very long periods of silence can be observed.
Up to now, outbreaks of chikungunya fever have been reported in many overseas countries and territories: the tropical British, French and Netherlands territories in the Caribbean (see risk assessment), South America (French Guiana), Indian Ocean (La Réunion, Mayotte) and Pacific regions (French Polynesia, New Caledonia). Chikungunya fever has not been reported in, for example, Madeira, despite the presence of competent Aedes aegypti vector.
Risk assessment: Chikungunya outbreak in Caribbean region and South America, June 2014
The first outbreak in the Americas started on the Caribbean island of Saint Martin in early December 2013 and expanded through the Caribbean during the first half of 2014, then reached Central, South and North Americas in areas where Aedes aegypti is endemic.
Exposure to infected mosquitoes is the principal risk for infection in currently affected areas. Prevention of chikungunya fever among travellers and local residents is essentially based on personal protection against mosquito bites and vector control; these are the same as the preventive measures to be taken against dengue.
Rapid risk assessment: Chikungunya outbreak in Caribbean region
This risk assessment considers the outbreak of chikungunya on the Caribbean island of Saint Martin in early December 2013 which expanded through the Caribbean during the first half of 2014. This is the first documented autochthonous transmission of chikungunya virus in the Americas.