Susan Miller

USA TODAY

Corrections and clarifications: An earlier version of this story misstated the affiliated of Peter Hotez. He is a dean at Baylor College of Medicine.

The Zika outbreak has experienced a new first: The spread of the virus from state to state.

A Texas resident who recently traveled to an area of Miami known as a hot spot for local Zika transmission tested positive for the virus, the Texas Department of State Health Services said Monday.

While there's no evidence that Zika is spreading in Texas, the new case shows that states other than Florida are vulnerable. All that's required for the disease to spread in Texas is for mosquitoes to bite the infected person, incubate the virus, then bite others.

"This is the first Texas case to be linked to travel within the continental United States. The case will be classified as 'travel-associated' and is being investigated for more details," the department said in a statement..

The El Paso County resident sought testing in Texas after becoming ill. Texas health officials linked the case to Miami after examining dates of travel and the onset of symptoms. It was El Paso County's first Zika case. The Texas health department said the county had no other evidence of the virus or local transmission.

The Zika virus is usually spread from human to human by the bite of infected mosquitoes. It can also pass from mother to child, through sex and through blood transfusions. Both Texas and Florida have the mosquitoes that spread Zika, called the Aedes aegypti and Aedes albopictus. And both have experienced clusters of mosquito-borne diseases in recent years, including dengue and chikungunya. Those outbreaks have been relatively small, however, thanks to the widespread use of screens and air conditioning, which limit Americans' exposure to mosquito bites.

Infectious disease expert Peter Hotez notes that travelers infected with Zika have been returning to Texas for months.

"It's probably not a huge story, given that on any particular day there may be many people from Zika-endemic areas of Central America coming into El Paso," said Hotez, dean of the National School of Tropical Medicine at Houston's Baylor College of Medicine.

New Florida Zika cases prompt Miami travel warning

It is dangerous because it is linked to a birth defect known as microcephaly, which results in small heads and brain damage in infants. It has also been linked to infant eye abnormalities and Guillain-Barre Syndrome, a neurological disorder that can cause temporary paralysis.

There is no vaccine to prevent Zika and no treatment for microcephaly.

On Aug. 1, federal health officials took the unprecedented step of advising women who are pregnant to avoid a one-square-mile area north of downtown Miami where Zika was spreading by local mosquitoes after 10 more homegrown cases were confirmed.

Women who visited the neighborhood of Wynwood, known for its trendy shops, eclectic bars and street art installations, since June 15 were warned by the Centers for Disease Control and Prevention to avoid getting pregnant for at least eight weeks.

Until the identification of local transmissions in Florida, almost all Zika infections in the U.S. were diagnosed in people who traveled abroad or who had sex with a traveler.

Before the El Paso case, Texas reported 108 cases associated with travel to areas with active Zika transmission, Texas health officials said. There were no reported cases of Zika transmission by mosquitoes in the state.

"Texas has been on alert for Zika since January, and we're doing everything we can to delay local transmission here," Carrie Williams, with the Texas health department, said Monday. "This is another significant development, but not an unexpected one."

On Monday, Florida officials reported two new non-travel related cases of Zika in the state, bringing the number to 30 spread by local mosquitoes. The state also reported 28 new travel-related cases of Zika, which included 11 in Miami-Dade County, for a total of 440 travel-related infections.

There are 1,962 Zika virus cases in the U.S. at this time, according to the CDC.

Contributing: Liz Szabo

Follow Miller on Twitter @susmiller