Spain has recorded its first known case of the Zika virus being sexually transmitted, after a woman contracted it from her partner, according to health authorities in Madrid.

Her partner returned to Spain from a Latin American country. The woman most likely contracted the virus just after her partner returned, a spokesman for Madrid’s health authorities said.

The woman’s partner was diagnosed with the virus shortly after he returned from an unspecified country in Latin America, either in late April or early May.

According to Spanish media, the woman is not pregnant.

The Zika virus is spread by mosquitoes and has been linked to thousands of cases of microcephaly birth defects. The babies affected by the defect are born with brain abnormalities and undersized heads.

Countries in South and Central America, as well as some areas in Oceania and Pacific islands, have high numbers of recorded Zika cases. Brazil has declared a public health emergency over the disease.

The risk of Malta being affected by the virus was raised from ‘low’ to ‘moderate’ in June.