A new Italian study showed the Zika virus would survive in semen of infected men for up to six months after symptoms appear, local media reported on Thursday.
The study was carried out by Spallanzani National Institute for Infectious Diseases in Rome, and published in the Eurosurveillance medical journal in August, according to Ansa news agency.
It focused on the case of a man in his early 40s, who returned to Italy from a two-week long visit to Haiti in January 2016.
The patient developed high fever and rash for three days after returning to Italy, and had reported mosquito bites in Haiti, scientists explained.
"Laboratory analyses performed at day 3 after symptom onset showed blood cell count and liver function tests within the normal range," they wrote in their Eurosurveillance article.
Yet, testing for infectious diseases demonstrated the presence of Zika virus (ZIKV) in both plasma and urine. The presence of the virus was still detectable in plasma up to 9 days after symptom appeared, and in saliva from 15 to 47 days, respectively.
"Notably, persistent shedding of ZIKV RNA was demonstrated in semen, still detectable at 181 days after onset," the authors wrote.
Several cases of sexually transmitted Zika infections, to which birth severe defects are associated, have been already documented in the world, confirming the disease is not spread only through mosquitos.
Yet, the Spallanzani study's findings might have relevant implications.
"A remarkable aspect of this case was the long duration of viral nucleic acid shedding in semen," the authors said.
"Data from this case suggest a prolonged potential for sexual transmission," the authors added.
However, Italian scientists warned the presence of ZIKV RNA in semen would not necessarily imply the presence of infective virus in the body, since "it could just represent a trace of past infection."
The research was carried out in cooperation with the Dept. of Molecular Medicine, the Microbiology and Virology Unit, and the Infectious Disease Unit of the University Hospital in Padua, northern Italy.
Overall, some 61 cases of Zika infections were registered in Italy, and 1,136 in Europe up to Aug. 5, according to data by the European Centre for Disease Control and Prevention (ECDC).
All of these cases were travel-associated infections.
The Zika infection developed in pregnant women has been particularly linked to microcephaly and acute neurological defects in newborns. Earlier this year, the World Health Organization (WHO) suggested those pregnant women positive to Zika virus who choose to terminate should be granted access to safe abortions.
The Spallanzani Institute in Rome is Italy's major reference medical center for infectious diseases, and is part of the ECDC Network on the Zika virus emergency.