More than two billion people across the world could be at risk of contracting the Zika virus.
People in India, Indonesia and Nigeria are some of the most vulnerable to transmission of the disease, according to researchers writing in top medical journal The Lancet.
And Pakistan, Bangladesh, the Philippines and Vietnam could also be particularly at-risk of an outbreak because of their limited health resources.
Up to 5,000 passengers a month travel to these countries from places where Zika is endemic.
However, the researchers added the caveat that people already living in these countries could have developed some level of immunity.
The team, from London School of Hygiene and Tropical Medicine, Oxford University and the University of Toronto, wrote that ‘vast numbers’ of people were living in places where preventing, detecting and responding to the virus would prove difficult.
To work out the risk they looked at the numbers of people travelling from affected areas in South America to Africa and Asia, the climate in these regions, and the presence of Zika-carrying mosquitoes.
‘The impact on populations will also depend heaviy on the country’s ability to diagnose and respond to a possible outbreak,’ Dr Kamran Khan, the study’s author, said.
‘Our findings could offer valuable information to support time-sensitive public health decision-making at local, national and international levels.’
