Three Britons have been infected with Zika virus after travelling to South and Central America, Public Health England (PHE) has said.
The three travellers picked up the disease, which is linked to brain deformities in babies, through mosquito bites in Colombia, Suriname and Guyana, PHE confirmed.
Pregnant women have been warned not to travel to countries where the infection has been reported.
PHE said Zika "does not occur naturally" in the UK and added: "As of 18 January 2016, three cases associated with travel to Colombia, Suriname and Guyana have been diagnosed in UK travellers."
The virus is transmitted through mosquito bites and "is not spread directly from person to person", according to PHE.
"A small number of cases have occurred through sexual transmission or by transmission from mother to foetus via the placenta," a spokesman said.