Cases of the Zika virus have been reported at Calderdale and Huddersfield hospitals.
Three people were found to be carrying the virus when treated at the hospitals after returning from overseas.
Zika has been declared a “global public health emergency” by the World Health Organisation and has spread rapidly in South America after being reported in Brazil in May 2015.
Exerts said the virus, a mild infection which is not harmful for most people, was unlikely to spread in the UK.
But pregnant women are advised to delay travelling to affected countries overseas after evidence was found linking Zika to birth defects.
The cases at Calderdale and Huddersfield NHS Foundation Trust emerged in an infection control report to the organisation’s trust board meeting yesterday.
The report said: “Three patients have tested positive for Zika virus following return from foreign travel.”
The Zika virus is mainly spread by mosquitos and can be transmitted between humans by sexual contact.
Dr Gavin Boyd, infection control lead at Calderdale and Huddersfield hospitals, said: “There is no specific treatment for Zika and it usually wears off naturally after two to seven days.
“After a diagnosis patients are cared for by their GPs if needed.
“There is extremely low risk of contracting Zika virus in the UK as the mosquito that transmits the infection is not present in the UK, however it can be spread by sexual transmission.”
Zika has been linked to birth defects including microcephaly, which causes babies to have abnormally small heads.
NHS guidelines said: “It is therefore recommended that pregnant women postpone non-essential travel to areas with active Zika transmission until after pregnancy.
“Discuss your travel plans with your GP, practice nurse or a travel clinic.
“If travel is unavoidable, then you should take extra care to avoid being bitten by mosquitoes.”