#19,214
After going more than a week without any new reports, late yesterday the USDA updated their New World Screwworm dashboard to show 3 new detections; 2 (cattle) in Edwards County, Tx, and 1 (sheep) in Crockett County, Tx.
Previously, Edwards county had reported 2 cases (1 cattle, 1 goats), while this is the first report from Crockett county.
As discussed previously, the New World Screwworm (NWS) fly lays its eggs in exposed wounds on practically any warm-blooded animal, including birds. While reported cases remain low, most of our surveillance is among livestock, while infections in the wild go largely unmonitored.
The CDC describes its life cycle as:
New World screwworm infestations begin when a female fly lays eggs on open wounds or other parts of the body in live, warm-blooded animals. Most infestations occur in animals, but they also occur in people. The smell of a wound or body opening such as the nose, mouth, eyes, ears, or genitals can attract female flies. Wounds as small as a tick bite may attract a female fly to lay her eggs. One female can lay 200 – 300 eggs at a time and may lay up to 3,000 eggs during her 10- to 30-day lifespan.
Eggs hatch into maggots that burrow into the wound to feed on the living flesh. After feeding for about 7 days, larvae drop to the ground, burrow into the soil, and emerge as adult screwworm flies.
The arrival of the NWS this early in the summer maximizes the number of cycles that may occur before winter weather sets in, which greatly limits the spread and survival of the NWS.
While the USDA continues to release sterile flies in the infested areas, it will take many months - possibly more than a year - to ramp up sterile fly production enough to combat a multi-state outbreak.
This is only part of the USDA's 8-part plan (see below) to try to contain this threat.
The ultimate goal is not only to eradicate the NWS in the United States, but also to drive the screwworm back south to its old control line - below the Darien Gap in Panama - to prevent yearly reintroductions from Northern Mexico.
All of which means winning this battle will likely take years, not months.
Meanwhile, state veterinarians from as far north as Minnesota are considering their options (see MPR News Minnesota state veterinarian worries New World screwworm could enter the state).
Stay tuned.
