Idaho Adds Requirements For Animal Entry In Response To U.S. New World Screwworm Cases
The Idaho State Department of Agriculture instated additional state entry requirements for animals on Wednesday following detections of New World screwworm — a flesh eating parasite — in Texas and New Mexico
Idaho officials are treating the New World screwworm as the serious threat it is, implementing new entry requirements for livestock and other warm-blooded animals arriving from states with confirmed infestations. The measures include veterinary inspections, movement permits for animals coming from designated infestation zones, and warnings to pet owners that dogs and cats can also carry the parasite back into the state.
This is exactly the sort of precaution sensible stewards take before a problem becomes a catastrophe. Waiting until a flesh-eating parasite arrives in your herds is a poor substitute for keeping it out in the first place. Idaho's livestock industry, wildlife, and rural communities have far too much at stake to gamble on wishful thinking when a proven threat is already moving across the landscape.
NOTE: this article was originally published to Idaho Capital Sun on June 10, 2026. It was written by Abigail Gernstein.
The Idaho State Department of Agriculture instated additional state entry requirements for animals on Wednesday following detections of New World screwworm — a flesh eating parasite — in Texas and New Mexico.
The parasite, first confirmed in the U.S. on June 3, would pose a serious threat to Idaho’s livestock industry, should it spread to the state. The screwworm’s larvae burrow into, and feed on, the living tissue of warm-blooded animals, with the potential to cause severe wounds, pain and bleeding.
The agriculture department’s Wednesday administrative order requires a Certificate of Veterinary Inspection granted, at most, five days before arrival for all warm-blooded animals entering Idaho from states with New World screwworm infestations.
For animals arriving from a designated screwworm-infested zone, the state agriculture department has mandated that a copy of the movement permit from the state-of-origin allowing the animal to depart must be presented. As of Wednesday, the U.S. Department of Agriculture has only declared screwworm-infested zones in southern Texas.
State officials are also encouraging Idahoans to refrain from taking their pets to states with New World screwworm cases to help mitigate the spread of the disease.
“Dogs and cats are just as susceptible to the pest as livestock, but pet owners may be less aware of the importance of thoroughly inspecting their pets for fly larvae that are very small and easy to miss,” said Scott Leibsle, Idaho state veterinarian. “Owners who do decide to travel with their pets to states affected by NWS will be required to get a health certificate, from a veterinarian in that state, within 5 days of their return to Idaho.”
Spurred by significant losses of cattle to the screwworm, the USDA began efforts to combat the parasite in the 1950s and achieved full eradication in 1986.
Cases recurred in Florida in 2016, but the screwworm was dispelled by early 2017.
The consequences of a outbreak of the New World screwworm among cattle is especially serious for Idaho, as cattle and dairy production are the largest two sectors of the state’s agriculture industry.
“Idaho has been preparing for the possibility of New World screwworm reaching the United States, and we are well-positioned to respond,” said Chanel Tewalt, the state’s Department of Agriculture director. “We are coordinating closely with USDA officials and our counterparts across the West.”