Men travelling to Zika infected areas are being told safe sex should be on their agenda even after they return home.

That's the view Dr Stewart Jessamine, the Ministry of Health's Acting Director of Public Health, has given in a briefing on the disease to MPs today.

He said advice to travellers, or Olympians, is practice safe sex, and stay away from mosquitos by wearing repellent and long clothes.

"The only thing we've now added is that if you're a man you should probably practice safe sex for three to six months after you return. That's the key bit of information".

Dr Jessamine said the links between the Zika virus and brain defects in babies are getting stronger.

He said the virus's link to foetal abnormalities is getting stronger as more cases are followed longitudinally.

"Which show that there are, in many cases, ongoing infection in utero which is probably the cause in those cases, of the microcephaly and neurological damage that's seen".

Dr Jessamine is also advising any man travelling to a Zika infected country to practice safe sex for three to six months after returning, to avoid passing the virus on.