Pregnant women are being advised to postpone non-essential trips to Florida because of the Zika virus.
The advice comes a day after confirmation that three people have tested positive for the virus in Yorkshire after returning to the UK from abroad.
Calderdale and Huddersfield NHS Trust said that the patients were carrying the infection but released no further information.
A report from the trust’s director of infection prevention and control said these cases were identified in the period April 1 to June 30.
Infection control lead for the trust Dr Gavin Boyd, said: “There is extremely low risk of contracting Zika virus in the UK as the mosquito that transmits the virus is not present in the UK.
“A small number of cases of sexual transmission globally have been reported but the risk is very, very small. There is no specific treatment and it wears off naturally after two to seven days. After a diagnosis patients are cared for by their GPs.”
Meanwhile, Public Health England updated its travel advice after the first cases of Zika transmitted by mosquitoes on the US mainland appeared in the state.
The health body has said the risk in the state on the south-east coast of the United States is moderate, while many countries in South America, including Olympic host Brazil, is high.
The Zika virus has been associated with a birth defect called microcephaly, which results in children being born with abnormally small heads and brain damage.
More than 1,650 Zika infections have been reported in the US, but four patients in Florida have tested positive for the virus and appear to be the first not linked to travel outside the US mainland.
A total of 53 people have been treated in the UK for the infection.
The updated travel advice reads: “The risk in Florida is considered moderate based on the number and spread of cases and their demonstrated ability to implement effective control measures for similar diseases such as dengue - a virus transmitted by the same mosquito.
“Pregnant women should consider postponing non-essential travel to affected areas until after the pregnancy.
“At present, only a zone of about one square mile in Miami-Dade County is considered at risk of active transmission.”
Since the Zika epidemic began in 2015, nearly 5,000 cases of microcephaly have been recorded in affected regions.
On February 1 this year the World Health Organisation declared the epidemic an international public health emergency.
Worldwide concern has centred on north-east Brazil but more than 20 other countries have now been affected.
The mosquitos that transmit the infection are now thought to be able to live in colder climates, like in the UK.