This map shows the risk of Zika in cities around the world

More cities than previously thought could be at risk of Zika if two species of mosquitoes are found to be effective carriers of the disease, according to a new study.

The study has produced a map showing how likely Zika is to spread to 100 cities around the world – based on two different scenarios. It assessed the risk based on whether or not the two species of mosquito both became effective carriers of the disease.

The researchers then integrated this with international air travel data to and from currently affected areas to outline the risk to global cities.

Source: Gardner, Chen and Sarkar 2016

What does the map show us?

Both mosquito species have been detected as carriers of the virus, but currently only one type (Aedes aegypti) is believed to be effective at spreading the virus. Solid red circles on the map indicate the risk if just this species remains capable of spreading Zika. However, if the other species (Aedes albopictus) also becomes effective then the global risk increases significantly. This is reflected in the number of open, unfilled circles across Europe, Asia and North America.

With the size of the circle reflecting the estimated risk, the threat posed to southern areas of the USA and the Caribbean is clear. Equally, the global risk posed by both species becoming effective spreaders becomes obvious. Cities across Europe, and also Asia and Oceania, face the prospect of Zika outbreaks.

What is Zika?

First discovered in Uganda in 1947, Zika is a mosquito-borne disease causing fever, rash, joint pain and conjunctivitis. It has also been linked to severe complications in pregnancy. There were very few reported cases of the disease prior to 2007. However, a significant outbreak in South and Central America has been declared a Public Health Emergency of International Concern – for just the fourth time in history.

The WHO has described its spread as explosive, and has previously warned that 3 to 4 million people in the region could be affected this year.

As the map above shows though, it’s not just people in Central and Southern America who are potentially at risk.

Have you read?
Zika: how big is the risk?
What does the Zika virus mean for travel?