St. Louis Encephalitis Surfaces in Coastal Bend Mosquitoes as Kingsville Sprays for Three Straight Nights

While the rest of Texas has spent the summer watching West Nile virus counts climb, a different mosquito-borne threat has quietly surfaced along the Gulf Coast. Kingsville health officials confirmed that a mosquito pool trapped Tuesday, August 4, tested positive for St. Louis encephalitis virus — the first SLEV detection of the season in Kleberg County — and launched an immediate spraying response.

The infected mosquitoes came from a trap in the 700 block of East Lott Avenue. Beginning Friday night and continuing through Sunday, city crews are spraying within a one-mile radius of the site for three consecutive nights, then returning to re-trap and retest the area to see whether the intervention worked.

"We are working closely with Region 11 to ensure our response effectively reduces the threat of St. Louis Encephalitis Virus transmission," Kingsville City Health Director Emilio Garcia said, referring to the state health service region covering the Coastal Bend.

A widening picture

Kingsville isn't alone. Vector control workers in Robstown, about 40 miles east, found the virus in a mosquito pool in the San Pedro neighborhood, and Corpus Christi detected its second positive pool a week earlier. Robstown has taken the most aggressive posture of the three cities — crews there plan to spray affected neighborhoods every night until traps stop coming back positive.

No human infections have been linked to these detections, health officials said. But the virus's presence in three Coastal Bend cities at once puts the region on alert heading into the late-summer peak of Culex activity.

The forgotten flavivirus

St. Louis encephalitis belongs to the same virus family as West Nile and cycles through the same Culex mosquitoes, which is part of why it tends to get overshadowed. According to the CDC, most people infected with SLEV never develop symptoms. When illness does appear — typically four to 14 days after a bite — it starts like the flu: fever, headache, nausea, fatigue. Severe cases can progress to encephalitis or meningitis, with stiff neck, confusion, tremors, and in the worst outcomes, central nervous system damage. Among patients sick enough to be diagnosed, 5 to 20 percent die from the infection.

Texas has a long history with the virus. A 1964 Houston epidemic hospitalized hundreds and remains one of the largest urban SLEV outbreaks on record in the United States. Detections in Texas mosquito pools this year had previously been confined to West Texas.

What residents can do

Health officials across the three cities are repeating the standard drill: avoid outdoor activity at dusk and dawn when Culex mosquitoes feed, use repellent, wear long sleeves, and drain standing water where the insects breed. Local pulmonologist Dr. Humayun Anjum put the burden plainly in comments to KRIS 6 — municipal spraying helps, but "as individuals we need to do our part."

With spraying in Kingsville wrapping up tonight, retest results expected this week will show whether the one-mile containment zone held.