A Horse in Bandera County Moved the Screwworm Quarantine Into the San Antonio Metro

The Texas Animal Health Commission added four counties to its screwworm map on Tuesday, and the paperwork for each one begins the same way: a single sentence naming the animal that started it.

On Nov. 9 the parasite was found in a horse in Bandera County. That finding became Infested Zone 31, drawn over parts of Bandera and Medina counties. The same day it was found in a bovine in Reagan County, which became Infested Zone 32, over parts of Crockett, Irion and Reagan. Executive director Lewis R. Dinges signed both orders, each effective immediately and each in force until the commission releases the quarantine.

The state's restricted list went from 21 counties to 25 in an afternoon. Texas Public Radio's tracker, last updated Monday, still carried the older list: Brewster, Crockett, Culberson, Edwards, El Paso, Fisher, Hudspeth, Jeff Davis, Jim Hogg, Mitchell, Nolan, Pecos, Presidio, Reeves, Schleicher, Scurry, Starr, Sutton, Terrell, Val Verde and Zapata. By Wednesday morning the commission's own notice read 25, with Bandera, Medina, Irion and Reagan on it.

Two of those four have no detection of their own. The orders name a horse in Bandera and a bovine in Reagan; Medina and Irion are inside the zones because they sit next to the counties where the fly was actually found. That has been the shape of every designation since June — the boundary is drawn around a finding, not along a county line — but this is the first pair to carry the buffer this far east.

What makes Zone 31 different is not the parasite's behavior. It is the neighborhood. Bandera and Medina are both counted in the San Antonio metropolitan area, and Medina runs east until it touches the Bexar County line. Until Tuesday, no county under screwworm movement restrictions shared a boundary with Bexar. The commission designates "areas of" both counties rather than either county entire, so the precise boundary is a line on the zone map and not something the order's text spells out. The rule inside it, though, is stated without any hedge at all: no warm-blooded animal leaves without prior authorization, every animal that does leave is inspected and treated and issued a movement certificate naming the product used and the animal's official ID, and hides, carcasses and parts are inspected before removal. Moving an animal without that authorization carries administrative penalties or criminal prosecution.

The Hill Country around Bandera is cattle and goats, heavy whitetail, and a growing number of small equine operations on subdivided ranch ground. A horse is a useful animal to find this parasite in. Horses get worked, trailered and hauled to shows, and a horse is rarely short of the thing a screwworm fly needs, which is an open wound — a wire cut, a saddle sore, a scrape nobody looked at twice.

The counts behind the map have moved faster than the map has. Texas Public Radio, working from USDA figures, put the outbreak at 126 confirmed animal infestations since June as of Monday, up from 79 on Nov. 1, which is close to 60 percent in eight days. Sixty-three were still active. All but two involved domestic animals; the exceptions were elk in Pecos and Jeff Davis counties, both now classified inactive. Federal surveillance had also caught wild screwworm flies in six traps by that count, four in October and one in November. Trapped flies are tracked separately from infested animals, and they say something a case count cannot: the fly is present in places where no one has yet found a wounded animal.

For most of the fall this has been a West Texas story — Pecos County, Culberson, Hudspeth, the counties stacked along the New Mexico line, then the Rolling Plains. Zone 31 changes the audience. A quarantine that touches the edge of the country's seventh-largest metro is a different kind of problem for veterinarians, for the stock shows and roping arenas where horses mix, and for anyone who keeps a few head on ten acres and has never had reason to read a movement order.

The commission's number for movement questions is 800-550-8242. What to watch next is whether Medina County produces a detection of its own or stays a buffer, and whether the counties west and north of Bandera follow it onto the list.