New World screwworm found in US wildlife for the first time, in a Texas elk

The New World screwworm, a parasitic fly whose larvae eat living flesh, has been found in American wildlife for the first time, in an elk on a game ranch in Pecos County, Texas, the US Department of Agriculture announced on Wednesday 21 October, CBS News reported. The animal was reported after a hunter shot it.

The USDA's Animal and Plant Health Inspection Service (APHIS) made the announcement. The USDA and the Texas Parks and Wildlife Department are stepping up surveillance of wildlife in the area, and the Texas Animal Health Commission will redraw the infested zone it set up earlier.

What screwworm is

The New World screwworm is a fly that lays its eggs in open wounds or body openings of warm-blooded animals. When the eggs hatch, the larvae burrow into and feed on living tissue, according to the US Centers for Disease Control and Prevention. It mainly attacks livestock and, rarely, people.

• Food: the USDA says it does not affect food safety, but it can hit meat production.
• Spread: it is usually found in South America and parts of the Caribbean, and in recent years has moved north through Central America and Mexico.

Second Texas case this year

This is not the first detection in Texas. In June, the USDA confirmed the parasite in a three-week-old calf in the state. The first US human case was confirmed last year; it was linked to travel, the patient recovered, and officials found no further spread.

Finding it in a wild animal is a bigger worry for farmers than a single calf, because deer and elk move freely between ranches and are much harder to check and treat than herds behind a fence.

Warning signs officials want reported

Hunters, ranchers and pet owners are asked to report at once any animal with:

1. visible maggots in a wound;
2. a foul-smelling injury;
3. an open wound that keeps getting bigger;
4. infestation around the nose, mouth, ears, eyes or genitals;
5. signs of weakness or distress.

Why it matters to readers here

The screwworm in this outbreak is the New World species, which is not established in Pakistan. Livestock keepers here deal with other wound myiasis flies, and the advice is the same in any country: treat and cover wounds on animals quickly, especially after castration, tagging or calving, and call a vet if you see larvae. For readers in the US with family ranches or pets in Texas, the reporting line is the Texas Animal Health Commission.