The World Health Organisation has urged women in Zika virus zones to have safe sex and cover up to avoid contracting the mosquito-borne disease.

Women in areas with the Zika virus can protect themselves, especially during pregnancy, by covering up against mosquitoes and practising safe sex through the use of condoms, says the World Health Organisation.

The Geneva-based United Nations agency issued recommendations on Wednesday for women regarding microcephaly and other neurological disorders linked to the mosquito-borne Zika virus that has been found in more than 30 countries including Brazil, where babies with birth defects have been reported.

It did not recommend travel restrictions, instead suggesting that women consult their doctors or authorities if travelling.

More evidence is needed to confirm whether sex commonly transmits the Zika virus, WHO said, noting that Zika has been found in semen and citing a report of sexual transmission in the United States.

There is no vaccine or treatment for Zika.

Pregnant women in general, including those who develop symptoms of Zika virus infection, should see their health care provider for close monitoring.

But WHO was also somewhat reassuring, declaring: "Most women in Zika-affected areas will give birth to normal infants."

Microcephaly is a rare condition where a baby is born with a small head or the head stops growing after birth.

It can result in developmental delays as well as seizures, hearing loss, vision problems and trouble swallowing.

"Early ultrasound does not reliably predict microcephaly except in extreme cases," WHO said.

Zika virus has been detected in breast milk but there is currently no evidence that the virus is transmitted to babies through breastfeeding, it said.

The outbreak of Zika across the Americas has raised the issue of a woman's reproductive rights including abortion.

"Women who wish to terminate a pregnancy due to a fear of microcephaly should have access to safe abortion services to the full extent of the law," WHO said.