(FOX NEWS) - Amid growing concern over an increasing number of Zika cases in the Americas, scientists are now cautioning that the usually mosquito-borne virus may be transmitted not only by vaginal sex, but also by oral sex and kissing.
In a letter to the New England Journal of Medicine, a peer-reviewed medical journal, scientists detailed one such case in France. A 46-year-old French man reportedly stayed in Brazil, a Zika hotspot, from Dec. 11, 2015 to Feb. 9, 2016, and unknowingly contracted the virus during his visit. Thereafter, he returned to Paris and had seven sexual encounters with his healthy 24-year-old female partner, who developed Zika symptoms on Feb. 20, 2016. According to scientists' letter, she had not been taking medication or receiving blood transfusions. She also had not traveled to a Zika-afflicted region in recent months. The Aedes aegypti and A. albopictus mosquitoes, the main vectors of Zika, do not reside in Paris.
The couple was not using condoms during sex, but the male partner ejaculated only during oral sex as a form of birth control, according to the letter.
Scientists wrote in the letter that they could not "rule out the possibility that transmission occurred not through semen but through other biologic fluids, such as pre-ejaculate secretions or saliva exchanged through deep kissing." They noted that the male partner's saliva tested negative for Zika after he began exhibiting symptoms, but it was not tested earlier.