MIAMI — In a highly unusual travel warning, health officials advised pregnant women to avoid a part of Miami where mosquitoes are apparently transmitting Zika directly to humans.

Health officials last Friday announced that mosquitoes have apparently started spreading Zika on the U.S. mainland, citing four cases they strongly believe were caused by bites. Ten more cases were announced Monday, even though Florida authorities have yet to find any mosquitoes actually carrying the virus.

Of the 14 people infected, two are women and 12 are men. Eight patients showed symptoms of Zika, which can include fever, rash, joint pain and red eyes. The others had no symptoms. The disease is often so mild that most people don’t know they are infected.

All 14 cases are thought to have occurred in Miami’s Wynwood arts district, a trendy, fast-gentrifying neighborhood of warehouses, art galleries, restaurants and boutiques.

Rosemary LeBranch was doing laundry in Wynwood when health officials came to her house a few days ago and took urine samples from her, her daughter and her father. Her father, Gabriel Jean, tested positive for Zika, she said Monday.

He had already spoken with a doctor and was advised to wear long shirts and pants outdoors.

“He said nothing hurts; he doesn’t have any pain. He doesn’t feel anything,” she said.

More than 1,650 cases of Zika have been reported in U.S. states. Nearly all have been the result of travel to a Zika-stricken country or sex with someone who was infected abroad, but now more than a dozen people have been infected in the U.S.