US health authorities push for measure against Zika virus

Zika fears have prompted US health authorities to issue a travel warning for a small section of Miami where local mosquitoes have spread the Zika virus to 14 people, officials said.

The warning was issued for a one-mile section north of central Miami.

"We advise pregnant women to avoid travel to this area," Centres for Disease Control and Prevention chief Tom Frieden said on Monday, adding that pregnant women who live in or may have travelled to the area since 15 June should talk with their doctor.

Pregnant women in the area have reportedly also been urged to use barrier protection during sex, or to abstain in order to lower the risk of transmission from a partner.

Frieden recommended the use mosquito repellent, wearing long sleeves, repairing screens and draining any standing water to prevent the spread of the mosquitoes.

"In Miami, aggressive mosquito control measures don't seem to be working as well as we would have liked," Frieden said. “It was possible that mosquitoes are resistant to insecticides currently being used, or that they may have hidden breeding areas that haven't been found yet, or that they are simply difficult to control.

The Zika virus is spread mostly by the bite of an infected Aedes species mosquito. These mosquitoes are aggressive daytime biters but can also bite at night. Zika can be passed from a pregnant woman to her foetus,  cause certain birth defects such as microcephaly. There is no vaccine or medicine for Zika.