Fifty-three people have been confirmed with Zika virus in the UK, Public Health England has said.

In the most recent cases, a hospital trust said three people had been treated for the virus in Yorkshire.

The Calderdale and Huddersfield NHS Trust said the three had returned from overseas have tested positive for the Zika virus. The condition of the patients is unknown, but the infection itself is mild – some people do not even know they have it – and does not require hospital treatment.

Two cases have been confirmed in Ireland.

An infection control report submitted to the Calderdale and Huddersfield hospitals’ trust board on Thursday said: “Three patients have tested positive for Zika virus following return from foreign travel.”

Dr Gavin Boyd, infection control lead at the trust, said: “There is no specific treatment for Zika and it usually wears off naturally after two to seven days.

“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 virus is widespread across Latin America and particularly in Brazil, which is about to host the Olympics. However, the mosquito-breeding season is now over and the danger of transmission of the virus is low.

On Friday, four patients in Florida became the first of 1,650 to be infected by the virus in the United States whose illness is not linked to foreign travel. Florida’s governor said the state had concluded that the infections probably came from mosquitoes in the Miami area.

The virus has caused Guillain-Barre syndrome in a small number of people in Latin America. The syndrome can be triggered by viral attacks on the immune system and results in muscle weakness and sometimes patients are unable to stand without support. Most get better over time, however.

But the biggest concern is the link between zika infection in pregnant women and brain damage in their babies, which is now known to take forms other than just microcephaly (an under-developed head). Fourteen countries have reported microcephaly cases. The first baby born in Europe with microcephaly was reported in Spain this week. The mother had contracted both dengue fever and Zika virus while travelling in Latin America.

Zika virus is predominantly transmitted by the Aedes Egypti mosquito which cannot live in the cooler climate of the UK. There is a very small risk, however, of sexual infection.

The World Health Organisation and PHE are warning those intending to take part in the Olympics or go to Rio to protect themselves against bites while there and take precautions when they return. Some competitors, including golfer Rory McIlroy, have pulled out, even though the WHO says the risk of contracting Zika at the Olympics is very low.

PHE says men and women should use condoms for eight weeks after returning from an area where there is Zika virus and for six months if they experience any symptoms themselves.

Prof Paul Cosford, medical director of PHE, said in a statement: “We expect to see small numbers of Zika virus infections in travellers returning to the UK, but the risk to the wider population is very low as the mosquito that spreads the Zika virus is not found in the UK. As of 27 July 2016, over 50 cases have been diagnosed in UK travellers since January 2016. Public Health England is monitoring the international situation closely and the risk to the UK remains unchanged.

“If you have recently returned from an area where Zika virus transmissions are currently reported and have a fever or flu-like illness, seek medical attention without delay to exclude malaria and mention your recent travel.”