France's health minister said Wednesday that two overseas territories are entering an epidemic phase of Zika, and that measures have been taken to combat the spread of the virus.
France has warned people to take protective measures when traveling to overseas territories, Health Minister Marisol Touraine said.
The World Health Organization advised European countries to take action against the mosquito-borne virus given its increased risk of spread with the onset of spring and summer.
Touraine said that the overseas territories of Martinique and French Guiana have reported 2,287 and 245 potential cases, respectively. One hundred of those were confirmed in a laboratory, she said.
Ten cases have been reported in Guadaloupe, and one in Saint Martin.
Additionally, Touraine said that one of the nine cases reported in France since the start of the year has a "neurological form" of infection. But she added that the risk of an epidemic is low, because the mosquito that transmits the virus does not frequently appear on the mainland.
In the Copenhagen-based office of the WHO, head Zsuzsanna Jakab said that several travellers to Europe had been infected after visiting affected areas, for instance in Latin America. Jakab said the disease had not been transmitted within Europe due to the absence of the mosquito vector.
Zika has been compared to dengue and chikungunya, two other tropical diseases carried by mosquitos. But in Dallas, Texas, on Tuesday, health officials said they had confirmed the first case of virus transmission through sexual contact.
France said a risk of sexual transmission has not been formally established, but recommended the use of condoms in the region.
On Monday, the WHO declared a public health emergency over the Zika virus, which has mainly affected Brazil and other South American nations.
While infection from the virus often presents only minor symptoms, scientists suspect it may be linked to congenital microcephaly. Causation has not, however, been scientifically proven.
In Ireland, health authorities confirmed two unrelated infections among people who traveled to Zika-affected countries but said both adults are recovered and neither was at risk of pregnancy.
"The finding of Zika cases in Ireland is not an unexpected event as many other European countries have reported cases as a result of travel to affected areas," Irish health authorities said in a statement.
Concerns over a rapid spread of the virus are largely due to lack of vaccines and quick, reliable diagnostic testing. There is currently no known treatment for the virus, which is most frequently carried by the Aedes aegypti mosquito.