Second screwworm case found in Texas

A second case of New World screwworm has been found in a Texas calf, the Agriculture Department confirmed Friday. 

The case was found in a one-month-old calf in Zavala County, around 5.6 miles from the site of the first detection, which was announced Wednesday. It was found after "testing a number of suspect cases," according to a press release. 

“USDA has responded expediently with respect to this second detection, demonstrating our utmost preparedness," Undersecretary for Marketing and Regulatory Programs Dudley Hoskins said in the release.

He added: "Many models projected this pest would reach the United States last year, but thanks to USDA’s phenomenal work and our cooperation with state, federal, and industry partners, we’ve held it off until now—when we are far more prepared to respond. USDA has not wasted any time in this fight, we have defeated New World screwworm before, and we will do it again."

Larvae of the New World screwworm, a parasitic fly, burrow into the flesh of livestock using sharp mouth hooks. The pest was widely considered to be eradicated from the U.S. by 1966, though it re-emerged in the Southwestern U.S. for a few years in the late 1970s, according to a report from the United Nations Food and Agriculture Organization. After that, it was driven off U.S. soil until 2016, when an outbreak in the Florida Keys infested local deer before officials stamped it out.

However, it never disappeared from Latin America, and in recent years, has been pushing steadily northward through Central America and Mexico. It arrived in the U.S. earlier this week, as USDA officials on Wednesday confirmed a case in a 3-week-old calf near La Pryor. 

Hoskins said the second detection is within the movement control zone and enhanced sterile insect dispersal area set up following confirmation of the first. 

According to the release, the Animal and Plant Health Inspection Service has a "strike team" of veterinarians on-site in Texas. They began releasing sterile screwworm flies over the area on June 4 and will disperse 2 million twice a week "to disrupt the pest's lifecycle."

Another 4 million sterile flies are beng sent to Texas, which "will be deployed using 24 ground release chambers, strategically placed in and around the detection zone to maximize impact," the release said.

USDA's National Veterinary Services Laboratories sent an entomologist to a Agricultural Research Service lab in Kerrvile, Texas, to help with the confirmation, according to the release. APHIS will maintain a 20-kilometer infested zone, which is subject to quarantines, movement controls and surveillance. The agency is also sourcing treatment supplies from the National Veterinary Stockpile. 

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