MIAMI • Florida health officials have found evidence of local Zika virus transmission in Miami Beach, one of the world's most popular tourist destinations, opening a new front in the fight against the mosquito-borne virus, said a source familiar with the investigation.

A handful of Zika cases had been identified and health officials were deciding which area or areas to include in any updated travel guidance, the source said. An announcement is expected soon.

The virus, which has spread rapidly through the Americas since it was first detected in Brazil last year, can cause the rare birth defect microcephaly, which is marked by abnormally small heads and developmental problems.

A spokesman for Florida's health department, Ms Mara Gambineri, said the department believes active transmissions were occurring in a small part in the Wynwood area of Miami but acknowledged two new Zika cases outside it. "If investigations reveal additional areas of likely active transmission, the department will announce a defined area of concern," she said in a statement.

Miami Beach mayor Philip Levine told a press conference late on Thursday that state and federal health officials had yet to conclude the tourist hot spot is the latest area where Zika has been transmitted.

"We don't know the exact link, one could be a tourist, one could be someone who may have worked on Miami Beach," Mr Levine told reporters. "If it was confirmed, we'd be able to talk about that, but it's not."

So far, there have been 35 cases of likely local transmission in the state, including the two new cases announced on Thursday.

The prospect of the virus spreading to the tourism-dependent Miami Beach area is likely to alarm tourism officials. Last year, some 15.5 million people spent at least a night in Greater Miami and the beaches, generating nearly US$24.4 billion (S$33 billion) in direct expenditures, according to the Greater Miami Convention & Visitors Bureau. More than 48 per cent of all visitors stayed in Miami Beach.

REUTERS