(CN) - Health officials said Wednesday that the Zika virus may remain in semen for weeks or even months after infection, adding a new risk to men - and their partners - who travel to regions with active Zika transmissions.
While previous travel advisories have focused on pregnant women, the lack of certainty about how long the virus remains active in semen is adding to concerns over the danger that Zika poses.
While only 20 percent of infected adults experience symptoms, Zika's possible link to microcephaly and other birth defects pose the most significant risk.
With few tangible symptoms, health experts have stressed taking precautions against Zika infection, especially if a woman is pregnant or having unprotected sexual contact with a male partner who has visited an affected region.
A letter submitted by British researchers to the Centers for Disease Control and Prevention detailed the case of a British man who was diagnosed with Zika after returning from a trip to the Cook Islands in the South Pacific. The 68-year-old man had a fever, felt lethargic and experienced a rash.
Although the researchers noted a "low viral load, commonly observed even in the acute phase of disease," they tested his blood, urine and semen twice after diagnosis - at 27 days and again at 62 days.
They found the man's blood and urine were Zika-free at day 27. His semen, however, still tested positive for the virus 62 days after diagnosis.
"We want to learn as much as we can quickly to provide the best information we can to men and women thinking of starting a family," Dr. Anne Schuchat, principal deputy director for the CDC, told CNN.
Increased cases of microcephaly, a congenial disorder that results in reduced head size and brain damage in fetuses, have so far only been reported in French Polynesia, Brazil and Colombia.
However, a study involving over 5,000 pregnant women in Colombia may present greater insight into Zika's potential connection to microcephaly and Guillain-Barre syndrome, which was connected to five deaths there. Three of the patients also tested position for Zika.
Guillain-Barre causes the immune system to attack the nervous system and generally occurs a few days after exposure to a parasite, virus or bacteria.
At least 52 countries have reported local transmission of the virus, though cases in the United States, France and Italy were reported in areas where the primary mosquito vector, Aedes aegypti, was not present. This suggests that these transmissions were the result of sexual contact .
Florida's first confirmed case of Zika being sexually transmitted was reported on Wednesday, after a man contracted the virus. Previously, researchers did not know whether women could transmit Zika to men.
The Sunshine State now has 52 Zika infections.
The World Health Organization also sounded the alarm for pregnant women this week, saying evidence continues to mount regarding the link between Zika and birth defects.
"Since this emergency committee on Zika virus first met on Feb. 1, substantial new clinical and epidemiological research has strengthened the association between Zika infection and the occurrence of fetal malformations and neurological disorders," World Health Organization director-general Margaret Chan said at a press conference following the second meeting of the committee on Tuesday.
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