The Zika virus has been located in the sperm of an Italian man six months after his first diagnosis; a significant recurrence as this is twice as long as in previous reported cases.
This suggests that Zika can survive for much longer periods than has generally been believed.
Doctors at the Spallanzani Institute for Infectious Diseases in Rome said it pointed to the possibility that the virus was reproducing itself in the male genital tract.
This is obviously of concern, suggesting that the viruses could spread more readily than was thought to be possible.
The Zika outbreak was originally declared a global public health emergency by the World Health Organisation in February.
There has been considerable controversy over the Rio Olympic Games in Brazil, with numerous competitors pulling out of the competition owing to fears over the Zika virus.
It now seems that sexual transmission of Zika could be far more feasible and widespread than was expected.
Current guidelines recommend infected patients should use condoms or abstain from sex for at least six months after the onset of symptoms.
But these may now need to be revised after this isolated cases, even if no other similar individuals are located.
Christian Lindmeier from the World Health Organisation indicated that the authoritative organisation is assessing its guidelines for Zika.
“The Zika outbreak is a constantly evolving situation and every new piece of evidence is looked into and evaluated as to whether or not guidelines will need to be revised.”
The patient, who was in his early 40s, first presented symptoms after returning to Italy after a two-week visit to Haiti in January.
Follow-up testing showed the Zika virus was still present in his urine, saliva and sperm, 91 days after the onset of symptoms.
This remained positive after 181 days, nearly doubling the previous longest registered symptoms in the span of an individual of 93 days, located in a younger Frenchman.
“The results of this study confirm that the virus could replicate specifically in the male genital tract and may persist in semen,” an Italian team working on Zika indicated.
Since this outbreak occurred, it has been discovered that Zika infections in adults can result in Guillain–Barré syndrome.
Prior to this outbreak, Zika was considered a mild infection, as most Zika virus infections are asymptomatic, making it difficult to determine precise estimates of the number of cases.