A woman may have caught Zika virus from her partner during oral sex - or perhaps even through kissing - doctors have warned.

The 24-year-old, from France, was struck down with the illness after her partner returned from Brazil – where there is an epidemic of the virus.

In light of the extraordinary case, doctors have called for guidelines regarding the possibility of transmitting the virus orally through semen.

A woman may have caught Zika virus from her partner during oral sex - or perhaps even through kissing - doctors have warned. Zika is known to cause a birth defect called microcephaly, where babies are born with very small heads. Pictured is a doctor treating a baby born with microcephaly in Recife

The large and spreading outbreak of Zika that began in Brazilhas caused global alarm after thousands of cases of microcephaly in babies were linked to women who become infected with the virus while pregnant.

Microcephaly causes babies to be born with abnormally small heads and birth defects.

The virus has also been linked to Guillain-Barre syndrome, a serious condition of the peripheral nervous system which can cause muscle weakness and paralysis.

Now, medics from the Institut National de la Santé et de la Recherche Médicale - the French Institute of Health and Medical Research - in Paris, have written a letter to the New England Journal of Medicine describing the case.

They say the 24-year-old woman developed a fever, muscle and joint pain and an itchy rash on February 20.

The rash spread to her abdomen, arms and legs – and she was unwell for around a week.

The woman had never travelled to a region where Zika is rife – nor had she had a blood transfusion – other known ways the virus can be transmitted.

In light of the extraordinary case, doctors have called for guidelines regarding the possibility of transmitting the virus orally through semen. Pictured are mothers in Recife whose babies were born with microcephaly

But her 46-year-old partner had just returned from Rio de Janeiro – where Zika is rife.

During his last week in Brazil, he had suffered fever, headache and a rash - known symptoms of the virus - but his illness had ended when he arrived back in France on February 10.

Between February 11 and February 20 the couple had sex seven times – with each time involving vaginal sex – but without ejaculation – and oral sex with ejaculation.

After the woman fell ill doctors suspected Zika and the pair were both tested for the infection.

The man was found to have high levels of the virus in his semen and saliva.

The woman had Zika in her urine and saliva, and antibodies - cells which fight disease – in her blood.

But a swab of her vagina was negative.

The doctors added guidelines are needed to advise couples on how long they should use condoms for after the man has returned from an area where Zika is rife

In the letter, the doctors said the data supports the theory that the virus was Zika was transmitted sexually – either orally or during intercourse.

They added it may have even have been passed from the man to the woman through kissing.

They wrote: ‘We cannot rule out the possibility that transmission occurred not through semen but through other biologic fluids, such as pre-ejaculate secretions or saliva exchanged through deep kissing.’

In light of this couple’s story, the doctors called for better advice on Zika transmission for people who are sexually active.

‘Recommendations regarding the possibility of oral transmission of the virus through semen are needed.

They added: ‘Guidelines regarding how long men who are returning from an area where active Zika transmission is occurring should continue to use condoms during sexual contact with pregnant women and those of child-bearing age are lacking.’