New Florida Parasite Screwworm Could Eat Your Pet Alive

Resurfaced Parasite Could Eat Your Pet Alive

There is a new parasite that has resurfaced in Florida that could possibly eat your pet alive. On a narrow strip of road linking the Florida Keys to the mainland is the front line for the fight against maggots that can kill livestock and pets.
The New World screwworm has been confirmed in the Keys. Now those driving with animals must stop for agriculture officials to check for signs of the screwworm at the Key Largo visitor center.

On September 30th the U.S. Department of Agriculture confirmed that screwworm was killing rare, dog-sized deer found in the island chain. There hadn’t been an infestation of the parasite in the U.S. for 30 years. The last time there was an infestation it cost the U.S. livestock industry millions each year.

Florida Agriculture Commissioner Adam Putnam said the source of the infestation isn’t known, but hopefully isolating the Keys’ will help stop the screwworm from spreading again.

Florida’s fight against the screwworm fifty years ago had gave way to a kind of birth control for insect pests, which could potentially be helpful in the fight against Zika and other mosquito-borne viruses.

What Are Screwworms And How Can You Prevent Them

Screwworms, Cochliomyia hominivorax, are about the same size as common houseflies as adults, but they have orange eyes instead. The parasite lays eggs near open wounds in warm-blooded animals. Unlike most maggots, these larvae hatch and “screw down” into the host organism, feeding on living flesh along the way. After they cause substantial damage, distress and sometimes death to the host animal, the screwworms fall away from their host to pupate and turn into flies.

Photo: Lyle J. Buss, University of Florida.
Photo: Lyle J. Buss, University of Florida.

The flies don’t often fly very far, but infected animals can spread infestations if they move to new areas. Livestock and pets are at the highest risk, though in some rare cases humans can become infected as well.

Symptoms of a screwworm infestation include a festering wound or sore, unexplained lumps under the skin, and an unusual discharge or foul odor.

About 30 Key deer have been found dead or have been euthanized in the last two weeks because of screwworm.

Photo: Artist view of larval screwworms embedded in would. U.S.D.A. Emporia State Univeristy, Screwworm Eradication.
Photo: Artist view of larval screwworms embedded in wound. U.S.D.A. Emporia State Univeristy, Screwworm Eradication.

Back in the mid 1950’s when Florida was experiencing its last outbreak of the parasite, entomologists studying ways to counter the insect found that they could render males sterile through exposure to X-rays. Since female screwworm flies only mate once, releasing millions of sterilized males into the infested areas would relatively break the life cycle. When Florida began this sterilization method in 1958 it took less than one year for screwworms to be completely wiped out in the state.

Agriculture officials announced the release of millions of sterilized male screwworm flies on Tuesday. Any eggs produced won’t hatch, eventually killing the fly population over time.

Putnam said the releases may continue twice weekly for six months.

Chemical treatments are available for infested cattle and pets, but the sterilized insect release is so effective that pesticides aren’t necessary.