WHO reveals low to moderate risk of Zika virus outbreak in Europe during late spring and summer

The overall risk of a Zika virus outbreak across the WHO European Region is low to moderate during late spring and summer, according to a new risk assessment published today by the WHO Regional Office for Europe. While this risk varies across the Region, it is higher in countries where Aedes mosquitoes are present.

“The new evidence published today tells us that there is a risk of spread of Zika virus disease in the European Region and that this risk varies from country to country,” says Dr Zsuzsanna Jakab, WHO Regional Director for Europe. “With this risk assessment, we at WHO want to inform and target preparedness work in each European country based on its level of risk. We call particularly on countries at higher risk to strengthen their national capacities and prioritize the activities that will prevent a large Zika outbreak.”

Results of the risk assessment

WHO assessed the risk of an outbreak in Member States in the Region and Lichtenstein, based on the combination of two factors: the likelihood of Zika virus spread and existing national capacity to prevent or rapidly contain local transmission.

Likelihood

The likelihood of local Zika virus transmission, if no measures are taken to mitigate the threat, is moderate in 18 countries in the European Region and high in limited geographical areas: the island of Madeira and the north-eastern coast of the Black Sea. In detail, this means that:

• the areas in the Region with the presence of Aedes aegypti, the primary Zika vector, have a high likelihood of local Zika virus transmission;
• 18 countries (33%) have a moderate likelihood, owing to the presence of Aedes albopictus,  a secondary Zika vector; and
• 36 countries (66%) have a low, very low or no likelihood, owing to the absence of Aedes mosquitoes and/or suitable climatic conditions for their establishment.

Capacity

The results of a questionnaire on capacity – how fast and well a country would respond to Zika virus spread – from 51 Member States in the Region and Liechtenstein indicate that 41 countries (79%) have good and very good capacity, although specific capacities varied substantially.

Risk

Combining the likelihood and capacity results provided the estimated level of risk of a Zika virus outbreak. The results show that across the WHO European Region the risk is low to moderate during late spring and summer.

Recommendations to European countries

For the purpose of recommendations, WHO focused on the likelihood, not the risk, of Zika virus spread. For countries with high and moderate likelihood of local Zika virus transmission, WHO recommends:

• strengthening vector-control activities to prevent the introduction and spread of mosquitoes, and reduce their density (particularly for areas with Aedes aegypti);
• equipping health professionals to detect local transmission of Zika virus early and to report the first case of local transmission, as well as complications from infections, within 24 hours of diagnosis;
• ensuring that the skills and capacity to test for Zika virus or protocols to ship blood samples abroad are in place;
• encouraging communities to reduce mosquito breeding sites;
• enabling people at risk, especially pregnant women, to protect themselves from infection, including through sexual transmission; and
• mitigating the effects of Zika virus and its complications.

All other countries should focus on adopting vector-control strategies according to their likelihood of local Zika virus transmission, detecting imported cases of Zika virus early and providing public health advice to travellers to and from affected countries, including on sexual transmission.

WHO response

“We stand ready to support European countries on the ground in case of Zika virus outbreaks,” says Dr Nedret Emiroglu, Director of the Communicable Diseases and Health Security Division, WHO Regional Office for Europe. “Our support to countries in the Region to prepare for and respond to health risks such as Zika is a key aspect of the reform of WHO’s work in emergencies.”

To address the risk of Zika virus spread in the European Region, WHO is scaling up efforts:

• to provide guidance on vector control in coordination with other sectors;
• to facilitate the shipment of samples to WHO reference laboratories or deliver diagnostic tools for local testing; and
• to advise on risk communication and community engagement.

WHO will convene a regional consultation in Portugal on 22–24 June 2016 to examine the conclusions of the risk assessment and identify countries’ needs, strengths and gaps in relation to preventing and responding to Zika virus disease.