To date, there have been no reported cases of the New World screwworm in Missouri, but that doesn’t mean that cattle farmers and others aren’t preparing themselves against the possible threat.
The New World screwworm is a parasitic fly that lays its eggs in open wounds and body orifices, such as ears, eyes, noses, genitals and anuses.
The larvae, or maggots, once hatched, feed on living tissue. This can lead to worsening wounds, secondary infections and death, if left untreated.
“What makes it a little bit different than our domestic fly species larvae... they only feed on necrotic tissue, whereas New World screwworm larvae feed on live tissue,” said Craig Payne, the Director of Veterinary Extension at the University of Missouri. “So, essentially what's happening is that these screwworm larvae are eating the animal alive in order to complete a particular phase of their life cycle.”
Payne said while the attention has been on cattle and other livestock, it’s important for people to remember that the parasite can impact any warm-blooded animal.
“We're just not talking about a threat to livestock or cattle, but we're also talking about a potential threat to household pets, wildlife – again, anything. There are cases that have been occasionally reported in humans as well,” Payne said.
He said the best thing people can do is keep a close eye on their livestock and pets, as well as make sure that any open wounds are quickly treated and covered.
"[There is] some information that will suggest even something as small as a tick bite is a location in which these can gain entry."Craig Payne, Director of Veterinary Extension at the University of Missouri
“That could be anything from a cut associated with coming up against barbed wire to… in the umbilicus of newborn animals, and you will see some information that will suggest even something as small as a tick bite is a location in which these can gain entry,” Payne said.
Mike Deering, the executive vice president of the Missouri Cattlemen’s Association, said the association is working closely with neighboring states to ensure that any infected animals stay contained and don’t cross state borders.
“[This is to] make sure that we are not disrupting the marketplace and that we continue providing safe, affordable beef products for our consumers, but also protecting herd health and human health, as well,” Deering said.
He said farmers should remain diligent with comprehensive pest strategies, as well as handle and examine their herds daily to watch for signs and symptoms of the parasite, such as growing or foul-smelling wounds, animals acting agitated or withdrawing from the herd.
But Deering stressed that the single most important thing a cattle farmer in Missouri can do right now to prepare is make sure they have a relationship with a large animal veterinarian.
“They're critical boots on the ground, that's your first step, and that's what you need to do today,” Deering said. “If you do not have a relationship – get one.”
There is an ongoing national shortage of large animal and food animal veterinarians in the country, but Deering said if you need to be connected to a veterinarian in your area, to contact the Missouri Veterinary Medical Association or the Missouri Cattlemen’s Association.
He added that while the New World screwworm is a devastating pest of the cattle industry, it does not pose a risk to food safety.
