Venezuelan Equine Encephalomyelitis, a nerve disease sometimes fatal to horses but also dangerous to humans, reached epidemic proportions in Colombia, South America, in December 1967. Carried by mosquitoes, it spread through Central America and Mexico during the next three years. By July 3, 1971, the disease had reached Brownsville, Texas, prompting the Department of Agriculture to request Air Force assistance with aerial spraying of insecticide on July 6.
The 4500th Air Base Wing from Langley AFB, Virginia, deployed two C–123 spray aircraft to Brownsville on July 8. Between July 9 and 12, the planes sprayed 120,000 acres with 2,400 gallons of insecticide. Despite these efforts, the disease spread, persuading the Department of Agriculture to ask the USAF for a larger operation. More C–123s, this time from the 319th Special Operations Squadron at Hurlburt Field at Eglin AFB, Florida, arrived in Brownsville on July 12.
On July 17, Col. Edward F. Borsare of the Tactical Air Command’s 1st Sp Ops Wg took command of a Combat VEE task force. By July 20, he had gathered the spray aircraft from Brownsville at his headquarters at Ellington AFB near Houston. That same day, the 548th Special Operations Training Squadron deployed nine C–47s to Ellington to participate in the operation. The 24th Special Operations Squadron at Howard AFB in the Panama Canal Zone sent a C–123 on August 3, becoming the fourth organization involved in the spraying missions.
Between July 8 and August 8, the Combat VEE task force flew 258 sorties in 597 flying hours, spraying over 3.5 million acres from Brownsville to Louisiana with more than 63,000 gallons of insecticide. Eighteen C–123 and C–47 aircraft flew during the operation, primarily in the early morning hours because effective spraying required moderate temperatures. By August 8, the combination of Air Force and civilian aerial spraying had halted the epidemic.