Health officials have announced the first case of Zika transmitted by local mosquitoes in Texas, the second state in the country to find local mosquitoes apparently carrying the virus.

The tropical virus country-hopped through Latin America and the Caribbean in the last year, first arriving in the United States in the territory of Puerto Rico, before arriving in Miami, Florida. Zika can cause severe birth defects in pregnant women infected with the disease.

“We knew it was only a matter of time before we saw a Zika case spread by a mosquito in Texas,” said Dr John Hellerstedt, the state health commissioner.

Until Monday, Texas had 257 confirmed cases of Zika, though all were associated with travel or sexual transmission. Zika is most commonly spread by infected mosquitoes.

“We still don’t believe the virus will become widespread in Texas, but there could be more cases, so people need to protect themselves from mosquito bites,” Hellerstedt said. “Especially in parts of the state that stay relatively warm in the fall and winter.”

The announcement comes one week after Florida governor Rick Scott sought to quell Zika anxiety in Miami.

The governor held a press conference to announce that three miles of Miami Beach, a popular winter tourist destination, was “cleared” of active Zika transmission. Pregnant women are still advised to postpone travel to about 1.5 miles of Miami Beach, and a nearby area of Miami-Dade county called Little River.

The World Health Organization also dropped Zika from the category of “global health emergency”, instead settling in for a long fight against the disease.

However, tools to fight the mosquitoes that carry Zika remain scarce. Mosquitoes can grow resistant to pesticides, and the widespread application of common airborne sprays has prompted outcry in some places, such as Puerto Rico.

Further, alarming discoveries about the virus have continued.

For example, a study released in mid-November found some babies of Zika-infected mothers may develop microcephaly after children appear normal at birth. Children with microcephaly are born with abnormally small heads and suffer severe developmental disorders. Microcephaly is considered the most severe birth defect associated with Zika.

One Texas-based epidemiologist also criticized politicians’ focus on small geographic areas, such as Miami Beach, noting that public health officials are not surveilling for the disease, and that four out of five patients are asymptomatic.

“The idea that Zika is confined to a small, circumspect area of Miami is ridiculous,” said Dr Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston, Texas. “There’s probably a lot of transmission going on in Texas, Louisiana, Alabama and Florida that we’re not aware of because we’re not really doing active surveillance, so this is not a surprise at all.”

Though Zika infection is believed to be widespread in Puerto Rico, officials said they did not expect the disease to spread as far in Texas. Many epidemiologists believe that widespread window screens and air conditioning in Texas is responsible for hindering the spread of mosquito-borne diseases.

The infected area, in Brownsville, tends to be a hotspot for mosquito-borne diseases, Hotez said, including a recent case of Chikungunya.

The city is one of the poorest in Texas. Brownsville is the southernmost city in Texas, on the Gulf of Mexico bordering the Mexican state of Tamaulipas. In Cameron County, where Brownsville is located, almost half of children live in poverty, according to the Texas Tribune – the highest rate in the state.