Spanish health officials have said a pregnant woman who had returned from Colombia had been diagnosed with the Zika virus, in the first such known European case.

"One of the patients diagnosed in [the northeastern region of] Catalonia is a pregnant woman, who showed symptoms after having travelled to Colombia," the health ministry announced, adding she is one of seven cases in Spain and all are in good condition.

Here, the Health Service Executive has said two unrelated cases of Zika confirmed this week involved a man and a woman who had travelled to a Zika-affected country in the first four to five months. Both have recovered.

The HSE has said more cases can be expected in Ireland, but most people will not know they have the disease.

The organisation said the diagnosis of the first cases of the virus in Ireland is not unexpected, as many other European countries have reported infections - but the case in Spain is the first case of a pregnant woman. 

News of the mosquito-borne virus, thought to cause birth defects, first emerged in Brazil last year, and health authorities have warned the disease could infect up to four million people in the Americas and spread worldwide.

The fever starts with a mosquito bite and normally causes little more than a fever and rash.

But since October, Brazil has reported 404 confirmed cases of microcephaly where the baby's head is abnormally small - up from 147 in 2014 - plus 3,670 suspected cases. 

The timing has fuelled strong suspicions that Zika is causing the birth defect.

Spain's health ministry nevertheless sought to ease concerns, pointing out that all seven patients had caught the disease abroad.

"Up to now, the diagnosed cases of Zika virus in Spain ... don't risk spreading the virus in our country as they are imported cases," it said.