First U.S. human case in decades raises alarm in NJ over screwworms

A disturbing species of parasitic fly has been creeping north after being declared eradicated decades ago in the U.S.

New World Screwworm, while still in their larval stage, have the ability to eat through live tissue.

If that sounds horrifying to any non-scientist, it is indeed very unusual, according to Rutgers University Entomology Chairwoman Dina Fonseca.

Most flies are associated with either excrement (poop) or decomposing tissue.

Myiasis is the official term for such a parasitic infestation of fly larvae in living tissue.

"I tell my students, whatever you do, do not Google 'myasis' because you'll have nightmares," Fonseca said.

The infection begins when a female fly lays eggs in an open wound or other entry point.

The flies have been causing alarm in Texas, as they can decimate herds of cattle.

And recently, the first U.S. human case in over 50 years was confirmed in Maryland, in a person who had traveled to South America.

So, is this a cause for concern in New Jersey?

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What is the likely NJ impact?

That human element is not something that New Jerseyans should be worried about, Fonseca said.

She said it is still extremely rare, and that any person without very serious underlying conditions would notice the unpleasant start of infection and can undergo treatment to have it cleaned and dealt with.

She said it's a different story for livestock, such as cattle.

They are vulnerable not just through open wounds but also the face area, since such animals cannot reach to brush flies away.

Are NJ cattle at risk?

Screwworms are not likely to impact New Jersey cattle, since flies cannot survive the cold and winter months, Fonseca said.

It is a very different public health issue than say bird flu was in dealing with the scarcity of eggs, since that is a virus that spreads rapidly.

There is also a proven and effective method for controlling these fly populations.

For decades, there has been an international collaboration that exposes male flies to radiation, rendering them sterile and unable to reproduce.

They are then released in very large quantities to mate with female screwworm flies, which only mate once before dying off, Fonseca said.

Those efforts led to screwworms being declared "eradicated" from the U.S. since the late 1960s.

In 2017, there was a small outbreak targeting deer on the Florida Keys, which was successfully ended by the same use of sterile flies.

While eradicated in this country, this type of screwworm has remained endemic in Cuba, Haiti, the Dominican Republic, and countries in South America.

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