Mississippi remains clear of New World Screwworm
STARKVILLE, Miss. (PRESS RELEASE) – According to an MSU press release, while Texas and New Mexico are battling the appearance of the New World Screwworm in a few separate locations, no evidence of this pest has been found in Mississippi.
As of June 25, there have been 20 animal cases found in the U.S, with one in New Mexico and the rest in the central-southwest portion of Texas bordering Mexico.
Jerome Goddard, an MSU Extension professor of medical entomology, said the New World Screwworm is a member of the blowfly family that infests living things. Typical blowflies lay eggs on dead animals, and the developing larvae, known as maggots, eat the dead carcass.
“The problem with this particular species of blowfly is that it lays its eggs on living animals, and the larvae burrow into the living flesh of cattle and other livestock, causing serious damage and sometimes death of the animal,” Goddard said.
The New World Screwworm fly is about the size of a housefly but is greenish blue in color with golden yellow cheeks. Complicating matters is another blowfly common in the U.S. called the secondary screwworm fly that looks almost like the New World Screwworm, but it is harmless to people and animals.
“Screwworms used to be endemic in the entire southern half of the U.S., but they were eradicated in the 1960s to 1970s using the sterile male technique,” Goddard said. “This eradication process eliminated this pest from the U.S. all the way down to Central America.”
Despite the U.S. eradication, there are occasional introductions of the pests, and officials have to eliminate them again. Before the current screwworm fly threat, the most recent outbreak was in the Florida Keys in 2016.
Dr. Jim Watson, state veterinarian with the Mississippi Board of Animal Health and Mississippi Department of Agriculture and Commerce, said the state is prepared with a response plan if there is an incursion of the New World Screwworm. It will launch joint efforts by local, state and federal agencies, including the U.S. Department of Agriculture, MSU and the Mississippi Department of Wildlife, Fisheries and Parks.
“Our goal at the Board of Animal Health is to develop regulations and to put out information that will help, if possible, prevent the pest from coming back into Mississippi, and if it does, we have been working and planning on how we would respond to this,” Watson said.
Animal owners, including those with livestock and pets, are asked to help by monitoring their animals for signs of the pest.
“We’re asking for people to inspect their animals frequently. Look for wounds, draining tracks and places where flies land,” he said. “If you see a wound that has maggots or larvae, call your local veterinarian or our office so we can collect samples.”
Watson said the second highest number of New World Screwworm cases reported in Mexico are in dogs. Mississippi requires a health certificate before animals from Texas or another affected state are brought to the state.
“It can seem kind of frightening to animal owners, but it was eradicated back in the ‘60s and we can do it again,” Watson said.
The USDA’s Animal and Plant Health Inspection Service monitors and combats the New World Screwworm. Find the map of detections and more information at aphis.usda.gov.
