Three Britons infected with Zika virus through mosquito bites
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.
Dr Dipti Patel, director at National Travel Health Network and Centre, warned pregnant women not to travel to countries where there is an outbreak of the virus.
She said: "All travellers, especially pregnant women going to the Americas, should ensure they seek travel health advice from their GP or a travel clinic well in advance of their trip.
"We strongly advise all travellers to avoid mosquito bites and urge pregnant women to consider avoiding travel to areas where Zika outbreaks are currently reported.
"If travel is unavoidable, or they live in areas where Zika is reported, they should take scrupulous insect bite avoidance measures both during daytime and nighttime hours.
"Women who are planning to become pregnant should discuss their travel plans with their healthcare provider to assess the risk of infection with Zika and receive advice on mosquito bite avoidance measures."
Dr Hilary Kirkbride, travel and migrant health expert at PHE, said: "The symptoms of Zika are similar to other mosquito-borne infections such as dengue, chikungunya and malaria so laboratory testing is essential for the correct diagnosis.
"If you have recently returned from the Americas, including the Caribbean, and have a fever or flu-like illness, seek medical attention without delay to exclude malaria and mention your travel history."
The Foreign Office advised Britons to seek advice before travelling anywhere where the virus has been reported in the last year "particularly if you're pregnant or planning to become pregnant".
The Brazilian government has announced plans to fund a biomedical research centre to help develop a vaccine against Zika virus.
Health minister Marcelo Castro said the aim is to develop a prevention for Zika "in record time".
Brazil's health ministry reported around 3,530 babies have been born with microcephaly in the country since October 2015.
"Research results confirm four deaths related to maternal Zika virus infection - two newborns at term, who died in the first 24 hours of life and two miscarriages," a Travel Health Pro spokesman said.
US health chiefs issued an alert on Friday advising pregnant women to avoid travelling to Brazil and several other countries in the Americas where Zika outbreaks have occurred.
In March 2015 an Italian traveller contracted Zika virus after he visited Salvador de Bahia in Brazil.
Zika is transmitted by the female Aedes mosquito, a breed which cannot survive in the low temperatures of the UK, PHE said.
Dr Philip McCall, of Liverpool School of Tropical Medicine, said the Aedes bite during the day, which makes it harder to prevent infection.
"For most people who get infected it's quite minor - fever, aches, pains and a skin rash," he told BBC News.
"Many people don't even get hospitalised.
"The problem is in South America because women who are pregnant at the time of infection have given birth with microcephaly, which is a severe deformity and has severe consequences."
The virus has "exploded" in South America within the last three years, he said.
Countries in the Americas with confirmed locally-acquired cases include: Barbados, Brazil, Colombia, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Puerto Rico, Saint Martin, Suriname and Venezuela.