Folks who live in the Houston and Dallas-Fort Worth need swat teams — the kind that swat mosquitoes, not that respond to high-risk emergencies.

Dallas-Fort Worth appears at No. 6 and Houston at No. 7 on a new ranking of the worst U.S. metro areas for mosquitoes. Much further down on the 50-metro list are Austin at No. 37 and San Antonio at No. 39.

Pest control giant Orkin produced the list based on the number of mosquito treatments it provided to residential and business customers from April 1, 2016, to March 31, 2017. For the fourth year in a row, Atlanta tops the list.

“Mosquitoes are a public health threat,” Orkin entomologist Mark Beavers says. “Zika virus is currently one of the most notable illnesses that can be spread by mosquitoes, and it will likely be a problem again this year, especially in areas where the type of mosquito that can carry the virus thrives.”

Aside from Zika, mosquito-borne viruses include West Nile, chikungunya, and dengue.

Orkin says mosquitoes become more active as temperatures rise, with mosquito season typically running from April to October.

The Texas Department of State Health Service says it’s preparing for the transmission of the Zika virus throughout Texas during the 2017 mosquito season.

“Zika remains a significant health risk to pregnant women and their babies, and it’s only a matter of time until we see local transmission here again,” Dr. John Hellerstedt, the state health commissioner, said in April.

From January 1, 2015, through April 26, 2017, Texas reported 326 Zika cases, according to the federal Centers for Disease Control and Prevention (CDC).

The Houston Health Department is bringing together public health officials, health care providers, infectious disease experts, community-based organizations and government leaders on to help strengthen the city's efforts to combat the Zika virus. Keynote speaker Dr. Carl Vartian, an infectious disease expert, will explore the impacts of Zika in Brownsville, the only Texas city where local mosquitoes have transmitted the virus to people.

The symposium takes place on Thursday, May 11, at the Crowne Plaza-River Oaks, 2721 Southwest Freeway, from 8:30 am until 5 pm. Registration is free, but participants must register in advance. For more information, call 832-393-5076.