A leading British expert has warned pregnant women and couples looking to conceive to ‘think twice’ about travelling to parts of the US – including Florida, home to Walt Disney World – because of the growing threat of the Zika virus.

Those considering holidays to southern states including Texas, Louisiana and Florida – which contains Miami, Cape Canaveral and the Florida Keys – should look at alternatives, said Professor Jimmy Whitworth of the London School of Hygiene and Tropical Medicine.

There is currently no evidence that mosquitoes on the US mainland are infected with the virus, which can leave babies with under-developed brains if their mothers are infected during pregnancy.