Health officials announced Thursday a new Zika zone in Miami — a setback less than a month after declaring the nearby Wynwood neighbourhood cleared of the virus following aggressive mosquito spraying.

Five people have been infected with Zika in a 1.5-square-kilometre area of the city just north of the Little Haiti neighbourhood and about 4.8 kilometres north of Wynwood, according to a statement released Thursday by Gov. Rick Scott's office.

It is the third Miami-area neighbourhood identified where mosquitoes have transmitted the virus to people, after Wynwood and a tourist-friendly section of Miami Beach, which is still considered an active transmission zone. Wynwood was declared free of the virus after 45 days went by without any new infections.

These are the first such areas of transmission confirmed in the continental U.S., following major outbreaks in Latin America of the disease, which can cause major birth defects, including stunted heads.

A travel advisory for the area for pregnant women was expected, similar to current warnings for pregnant women to consider postponing non-essential travel to Miami Beach and the rest of Miami-Dade County, said Tom Skinner, a spokesman for the U.S. Centers for Disease Control and Prevention.

"We're not yet at the end of mosquito season, so we might continue to see local transmission going on for a little while yet," Skinner said.

Officials in Florida had warned that Hurricane Matthew would interrupt efforts to eradicate the mosquitoes that spread the virus, and Gov. Rick Scott had told residents to be mindful of draining standing water on their properties after the storm passed. However, Miami was not as seriously affected by the storm as other areas of the state.

Four cases from the new zone first reported symptoms in September, and the fifth began suffering symptoms earlier this month, Florida Department of Health spokeswoman Mara Gambineri said in an email.

The patients in the new zone include two women and three men, according to the statement from Scott's office. Three live in the area while the other two either visited or worked there.

Zika infections have been reported in over 1,020 people in Florida, the vast majority of them deemed related to travel to affected areas outside the country. Miami-Dade County has the largest share of the state's burden, with more travel-related Zika infections than any other Florida county.

Health officials have so far traced 105 cases to three Miami-area infection zones.

Scott has directed another $7.4 million US in state funding to hire more mosquito control staff and pay for more pesticide spraying in Miami-Dade County.

"We have seen that aggressive mosquito control efforts have worked in areas like Wynwood and we hope the county also aggressively sprays in this area so we can limit the spread of this virus and protect pregnant women and their growing babies," Scott said in the statement.

Health officials also were investigating a non-travel Zika infection reported Thursday in a Broward County resident. Officials there said aerial pesticide spraying targeting mosquito larvae would resume early Friday in the Fort Lauderdale area.