Health officials watching mosquitoes in Texas after Harvey

DALLAS — Health officials in Texas will be on watch in coming weeks for any increases in mosquito-borne diseases including the West Nile and Zika viruses after Harvey’s heavy rains and flooding brought water that filled ponds and ditches and crept into trash and debris that piled up.

“We’re not out of the woods. I still think we don’t really know what we’re going to see, so that’s why we’ve got to monitor it,” said Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston. “The next month is going to be the critical time,” he added.

Officials are hopeful, though, that aerial and ground spraying done after Hurricane Harvey made landfall on Aug. 25 will help ensure that populations don’t swell. The Texas Department of State Health Services said more than 7 million acres were sprayed by plane across areas inundated from Harvey.

“It looks like they’ve gotten pretty good results,” said health department spokesman Chris Van Deusen, adding, “Hopefully it will prevent any kind of uptick.”

Of particular concern is West Nile. Texas trails only California this year in the number of cases of the virus, which is transmitted from infected birds to humans by the common Culex mosquito. Most people don’t develop any symptoms, but those who do may have fever, headache, vomiting and diarrhea. In rare cases, people develop severe illnesses such as encephalitis and meningitis, which can be deadly. Texas has had at least 100 human cases this year, including three deaths.

While there’s currently no evidence of ongoing transmission of mosquito-borne diseases including Zika, dengue or chikungunya in Texas — all three spread by the Aedes aegypti mosquito — officials are watching on guard for any emergence. That could happen if someone who had traveled to a place with active cases got the disease, returned to Texas and was bitten by a mosquito that in turn bites and infects someone else.