The first case of sexually transmitted Zika virus in Europe has been reported in France, Marisol Touraine, France’s minister for social affairs, health and women’s rights, said Saturday. The virus, which has been linked to congenital defects in babies born to infected pregnant women, was found in a couple in the Paris area, according to media reports.

Francois Bourdillon, the director general of the French Institute for Public Health Surveillance, told local media outlets that “the patient had not travelled [to Zika affected nations], her companion was returning from Brazil” where he was infected with the Zika virus. He also said the infected couple was “doing well.”

The Zika virus, which was until recently limited to a handful of countries in equatorial Africa and Asia, first appeared in Brazil in May. Since then, an estimated 1.5 million people are believed to have been infected in the country, and a total of 46 nations have reported some level of Zika infection.

Until now there have been no known cases of local transmission — infections that are generated within a country — in France, but authorities have detected such cases in the country's overseas departments and territories. In January, French medical authorities notified the World Health Organization (WHO) of two "locally acquired" cases of Zika virus in the overseas territories of Guadeloupe and  Saint Martin.

Although the Aedes mosquito-borne Zika infection normally causes mild symptoms, such as fever, rash, joint pain, and conjunctivitis, or no symptoms at all, health officials across the globe are concerned because the latest outbreak has been linked to a drastic increase in the rate of microcephaly — a birth defect in which babies are born with small heads and undeveloped brains.

“Every European country in which Aedes mosquitos are present can be at risk for the spread of Zika virus disease,” Zsuzsanna Jakab, WHO’s regional director for Europe, said in a statement released earlier this month. “Now is the time for countries to prepare themselves to reduce the risk to their populations. As there is no vaccine or treatment for Zika virus disease, we must protect the European Region by stopping the disease at its source. … As a precautionary measure, national governments may issue travel recommendations to their own populations after assessing the available evidence and local risk factors.”

In the U.S., for instance, in response to an increase in the number of travel-related cases of the infection, the Centers for Disease Control and Prevention recently issued a travel alert advising pregnant women to postpone travel to 14 countries and territories in the Americas affected by the Zika virus.