Regular summer travel to and from Zika-affected areas will place some parts of Europe at risk of the local spread of virus in the coming months, a new study suggests.
Barcelona, Milan and Rome are the most likely to be affected, with the risk highest in July and August, according to the research published in the journal EBioMedicine, according to Statnews.com.
Also at risk is Madeira, an archipelago of islands that is part of Portugal but located in the Atlantic, west of Morocco.
The findings will be of interest to an expert panel that was to meet Tuesday to consider whether World Health Organization should urge the International Olympic Committee to postpone the Rio Olympics.
At least 227 academics have signed a petition arguing that it is unsafe to hold the Olympics and Paralympics in Rio this summer.
Olympic organizers have estimated the games will draw 500,000 to 600,000 visitors to Brazil. Some scientists worry that the travel will expedite the global spread of Zika virus, projecting it to new places in the bloodstreams of athletes, officials and spectators who get infected in Rio.
But travel between the Zika-affected countries and Europe is already substantial, the study reported. Paris, for instance, normally gets between 120,000 and 200,000 travelers a month from Zika-affected countries during July and August. London gets as many as 130,000 and Madrid is not far behind.
Zika is spread mainly through the bite of infected mosquitoes. The primary species involved in its spread is Aedes aegypti, which is not found much in Europe. Another species, Aedes albopictus, is more commonly found, especially along the Mediterranean.
While there is evidence that these mosquitoes may be able to transmit Zika, it is uncertain if they will play a major role in spreading the virus.
“It is quite possible that we go through the year and we don’t actually see anything in southern Mediterranean Europe,” said senior author Kamran Khan, an infectious diseases specialist at St. Michael’s Hospital in Toronto, Canada.
“The risk is potentially there. But a lot of this hinges on how Aedes albopictus will actually act as a vector for Zika virus. And that’s still a bit of an unknown,” he said.
Khan cautioned that the research does not address how probable it is that local spread will take place. The right mosquitoes and an influx of infected travelers are key ingredients for local spread, but other factors like population density and housing conditions could also influence the likelihood of an outbreak.
“We’re saying if an outbreak is going to happen, these are the places we would expect it to be more likely to occur,” said Khan, whose research focuses on projecting how infectious diseases spread using international travel data.
