Protecting Dogs from the Dangerous Return of the New World Screwworm

Host Laura Reeves and veterinarian Marty Greer discuss the alarming resurgence of the New World Screwworm, outlining vital travel precautions, key symptoms to watch for and the medications used to treat this invasive parasite.

• The Return of a Lethal Threat:After being successfully managed since 1966 using a sterile fly release program, the New World Screwworm has crossed back over the U.S. border. Confirmed cases have already appeared in livestock and dogs.
• How Screwworms Differ from Normal Maggots:Unlike typical fly larvae that only infest damaged or dead tissue, New World Screwworm larvae aggressively penetrate and destroy healthy, normal tissue in dogs, cats, livestock and even humans.
• Fluid Travel Restrictions:State and international borders are experiencing rapidly shifting regulations. Dog owners are warned to avoid traveling across the Mexican border, remain highly cautious when traveling interstate and ensure they carry official health certificates.
• What to Do If You Find a Larva:This is a federally reportable disease. If you discover a larva in a wound, do not throw it on the ground where it can pupate. Instead, preserve it in alcohol or formalin and immediately contact your veterinarian to notify authorities.
• Treatment Options:Oral flea and tick medications in theisoxazolineclass (such as Cridelio, Nexgard, Brevecta, and Semperica) andnicotinamides(such as Capstar) are the primary medications utilized or suspected for emergency treatment, although their preventative capabilities are still being studied.
• Other Exotic Diseases on the Rise:The episode also flags other global health threats creeping into the U.S. due to warming temperatures, includingChagas disease(transmitted by the kissing bug and causing severe cardiac disease) and aliver flukeshowing up in the Colorado River Valley.

Featured Resources:

• Worms and Germs Blog(Infectious disease updates by veterinarian Dr. Scott Weese)
• CapcVet(veterinarian-authored parasite prevalence maps)