Zika Virus Updates: WHO Warns of 'Marked Increase' of Outbreak in Europe

— -- The Zika virus outbreak continues to spread throughout the Western Hemisphere, including in wide swaths of Central and South America, and concerns are growing for pregnant women because the mosquito-borne virus has been shown to cause a serious birth defect called microcephaly, characterized by an abnormally small head and brain.

Here are the latest updates about the outbreak, which the World Health Organization has deemed a "global health emergency."

WHO Warns of "Marked Increase" in Virus in Europe This Summer

Warming weather throughout Europe could mean the Zika virus will spread at a greater rate, a World Health Organization official said this week.

Dr. Marie-Paule Kieny, an assistant director-general for health systems and innovation at the WHO, addressed the possibility of an expanding range for the mosquitoes that spread the Zika virus.

With mosquito season arriving in Europe, "the possibility of local transmission combined with the likelihood of onward sexual transmission could see a marked increase in the number of people with Zika and related complications," she said, according to Agence France-Presse.

"As seasonal temperatures begin to rise in Europe, two species of Aedes mosquito, which we know transmit the virus, will begin to circulate," Kieny said, according to the AFP.

Currently, 42 countries are experiencing a first outbreak of Zika virus since 2015, with no previous evidence of circulation and ongoing transmission by mosquitoes, according to a WHO situation report last week.

Three European countries -- France, Italy and Portugal -- are among the eight countries that have reported person-to-person transmission of the virus via sexual contact.

Canada Reports First Case of Sexually Transmitted Zika Virus

Canada has reported its first case of person-to-person Zika transmission due to sexual contact.

An unnamed resident from Ontario is thought to have contracted the Zika virus from sexual contact with a partner. The partner was diagnosed with the virus after traveling to a country where the transmission of the virus is spread from mosquito to people, according to a statement from government officials on Monday.

There have been no confirmed cases if Zika spreading from mosquitoes to people in either Canada or the U.S. There have been a few cases reported of the virus transmitting through sexual contact in the U.S.