Zika virus 'spreads through sex'

3rd February 2016 - Health officials in the US have reported a rare case of Zika virus being transmitted through sex.

A person in Dallas, Texas is thought to have been infected by sexual contact with their partner who had returned from Venezuala, where Zika is active, according to the Centers for Disease Control (CDC).

Global health threat

On Monday, the World Health Organization (WHO) declared the Zika virus a threat to global health. It has been linked in Latin America to thousands of babies being born with microcephaly - a condition in which infants are born with, or develop in infancy, small, underdeveloped brains.

It is also being linked to cases of Guillain-Barré Syndrome which causes nerve damage and muscle weakness.

Zika is transmitted to humans by bites from aedes species of mosquito, including the Aedes aegypti mosquito, the same mosquito that transmits dengue fever, yellow fever and chikungunya.

However, the latest information from the US suggests that Zika could pose a threat to people in parts of the world where it is not being spread by mosquito bites.

Back in 2008, the CDC reported a possible case of a man spreading the virus to his wife through sexual contact in Colorado after becoming infected in Senegal. Although the wife tested positive, no one checked to see if the virus was in the man's semen, which would be evidence of sexual transmission.

The Texas case appears to be the first endemic case of Zika infection on US soil during this recent outbreak.

Condoms

In a statement, Zachary Thompson, director of Dallas County Health and Human Services, says: "Now that we know Zika virus can be transmitted through sex, this increases our awareness campaign in educating the public about protecting themselves and others. Next to abstinence, condoms are the best prevention method against any sexually transmitted infection."

Several experts have issued statements about the latest development.

Dr Nathalie MacDermott, clinical research fellow at Imperial College London, says: "While a previous case of possible sexual transmission was documented a few years ago, this new case of reported potential sexual transmission further emphasises the ongoing need for research into Zika virus, its presence in semen and how long it may potentially remain in semen follow recovery from acute infection."

Jonathan Ball, professor of molecular virology at the University of Nottingham, says: "With Zika, mosquitoes remain the main reason for the current outbreak, but this finding does support advice that a man should seriously consider using condoms if they have potentially been exposed to, or are infected with, Zika, if their partner is or might become pregnant."

Need for research

Professor Matthew Baylis from the Institute of Infection and Global Health at the University of Liverpool, comments: "As we saw with Ebola viral disease, it may be that the unprecedented number of cases, and close scientific and medical scrutiny, are revealing transmission routes that have not been recorded before.

"This route of transmission may be sufficiently rare (compared to spread by mosquitoes) that it will have little impact on the spread of the outbreak. Further research is clearly needed in this regard."