By Mike Hixenbaugh
State health officials confirmed Monday what many scientists have long suspected: The Zika virus has been transmitted by a mosquito in Texas.
Officials from the Department of State Health Services have descended on the state's southernmost county, along the Mexico border, where it's believed a woman in Brownsville was infected by a mosquito bite.
Cameron County health workers began going door-to-door in the woman's neighborhood Monday evening, helping people remove mosquito-breeding habitat from their yards and taking urine samples from residents to determine if anyone else has been infected.
"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 DSHS commissioner. "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."
There have been more than 250 confirmed cases of Zika in Texas this year; this is the first in someone who hadn't traveled to another country, officials said. The development makes Texas the second state, after Florida, to report localized transmission of Zika virus.
Dr. Peter Hotez, dean for the National School of Tropical Medicine at Baylor College of Medicine, has said for months that Zika has likely been spreading quietly in Texas, in part because the federal government was late in providing funding for active screening of patients.
He wasn't surprised by the report out of Brownsville.
"And don't be surprised if we see additional transmissions this year," said Hotez, noting that aedes aegypti mosquitoes remain active through most of December in the warmth of southern Texas. "It's not going to wind down immediately."
Difficult to track
Most people infected with Zika show no symptoms, another reason it's challenging to track the disease, said Dr. Scott Weaver, director of the Institute for Human Infections and Immunity at the University of Texas Medical Branch in Galveston.
The four most common symptoms among those who do become ill are fever, itchy rash, joint pain and eye redness. While symptoms are usually minor, Zika can also cause severe birth defects, including microcephaly, and other poor birth outcomes in women infected during pregnancy.
"Almost certainly other people have been infected," said Weaver, who began studying Zika a decade ago, long before it began spreading rampantly in South America. "The best thing to do now is to make sure health care providers think Zika if they see someone with a rash."
Pregnant women and their partners also need to take special care, Weaver said. The disease can be transmitted sexually.
The patient, a Cameron County resident, is not pregnant, officials said. The infection was confirmed last week by a state lab, though it's not clear when she was initially tested. She told health officials she hasn't traveled to Mexico or anywhere else Zika has been reported. Many Brownsville residents travel back and forth across the border for work.
'We were expecting this'
Hotez said it's likely the virus is spreading more quickly on the Mexican side, where fewer people have screened windows and air conditioning.
"We were expecting this," said Esmeralda Guajardo, the Cameron County health administrator. "It was only a matter of when. So we're telling people not to panic, just take precautions."
County and city officials have begun trapping and testing mosquitoes in the area where the woman lives. Health workers also are canvassing the areas -- about 24 city blocks in a dense residential section -- to educate residents and collect urine samples.
Pregnant women and anyone showing symptoms will be offered a blood test, Guajardo said.
The samples will be tested at a DSHS laboratory in Austin. The agency has delivered laboratory supplies, educational materials and mosquito traps to Cameron County. The Centers for Disease Control and Prevention also is providing assistance from afar.
Cooler weather helps
In Houston, where overnight temperatures are now regularly below 60 degrees, Weaver said peak season for the spread of mosquito-borne illnesses has passed. The threat, though, is likely to reemerge in the spring.
"At this point, there's no reason to start testing people all over the region or all over Texas," Weaver said. "Not yet."
(c)2016 the Houston Chronicle