ORLANDO, Fla. — Pet owners and livestock owners are being urged to watch for signs of New World screwworm after federal officials confirmed the parasite has returned to the United States.
The U.S. Department of Agriculture confirmed the first U.S. animal case in the current outbreak on June 3 in a calf in Zavala County, Texas. Additional cases have since been confirmed in Texas and New Mexico, including a dog, according to USDA updates.
New World screwworm is a parasitic fly. Its larvae can burrow into the living tissue of warm-blooded animals, causing serious wounds that can become life-threatening if not treated quickly, according to the USDA.
The Centers for Disease Control and Prevention said no locally acquired human infestations have been reported in the United States during the current outbreak. The CDC said the outbreak has been moving north through Central America and Mexico since 2023, mainly affecting livestock, pets and wildlife.
Veterinarians say pet owners should check animals for wounds, especially after flea or tick bites, outdoor activity or time around livestock.
Warning signs can include open wounds, a foul smell, visible larvae, swelling, unusual behavior or an animal repeatedly licking or scratching one area.
Federal officials said suspected cases should be reported immediately.
The warning comes as the CDC said emergency room visits for tick bites have also been higher than usual in many parts of the country. In April, the CDC said weekly ER visits for tick bites were at their highest level for this time of year since 2017 in all regions except the South Central U.S.
Pet owners should talk with their veterinarian about parasite prevention, especially for animals that spend time outside or may be exposed to ticks, fleas or open wounds.
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