New World screwworm on the move
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By Jeff Snyder
MOUNT AYR, Iowa — An old foe in the cattle world is making an unwelcome comeback across the United States.
The New World screwworm fly is once again starting to infect some cattle in the nation.
In recent weeks, new cases of Screw Fly infestation have been detected in the United States with most being in the southwestern portion of the country, primarily in Texas and New Mexico
The infestation has reached a confirmed 32 cases. Most of the cases are located in 21 specific counties located in southwest Texas. As a result, the Texas department of agriculture have teamed up with the (TAHC) Texas Animal Health Commission, and have introduced a livestock movement moratorium. No animals will be allowed to navigate outside the identified counties without prior approval of the TAHC. Texas agriculture personnel are keeping a watchful eye on the various illegal drug cartels as cattle shipping is a significant revenue tool for these groups. Changed ear tags, doctored vet certifications and illegal cross border shipping enterprises all contribute to the 320 million dollar illegal cattle traffic programs currently in place. These illegal activities can also lead to additional screw fly infestations
In the late 1950s the United States became a victim of an infestation that nearly crippled the U.S. cattle industry. Cochliomyia hominivorax, or the New World screwworm fly, made its way into the southern United States, via its native South and Central American habitats. In 1959, Florida had a significant outbreak with over one million cows infected. Wound treatments, chemicals and inspection costs saw millions in revenue losses in Florida alone.
This invasive species of fly seeks out open wounds on cattle and livestock and then lays eggs in the wound site. The fly larvae then burrow into the animal and cause extensive damage and ultimately death if left untreated.
By the mid 1960s these flies were nearly eradicated through an aggressive bio experiment called STI (sterile insect treatment) whereby millions of male flies were sterilized using low doses of radiation rendering the flies sterile. Once sterilized, the flies were reintroduced into the pathway of the invading insects and allowed to mate with the arriving females.
The New World screwworm only mates once in its lifetime. The sterile male flies gave rise to an unfertilized generation of insects eventually eradicating the pest. This method of control was considered one of the most successful cases of bio-engineering ever conducted.
It is believed that the COVID-19 crisis in recent years gave rise to a new infestation, as sterile fly introduction during this period nearly disappeared. The USDA is concerned that another widespread outbreak could further damage an already strained cattle production industry.
Although there have been no reported instances in the Midwest or Iowa in particularly, it is something that local cattlemen are paying attention to.
“Farmers and ranchers have to practice good husbandry,” long time area cattle rancher Colby Holmes said.
Fellow rancher Steve Knapp every cattleman must be watchful.
“It’s up to the rancher to keep an eye on his herds,” Knapp said. “You just have to take care of it before it gets out of hand. It’s not just cattle that can be effected, its any animal that has an open wound. Just take care of your animals.
Recent droughts and packing company issues have driven U.S. cattle herds to their lowest levels in 70 years. Wholesale beef prices and subsequently retail beef prices are at historic highs.
The blue print for controlling this invasion is already in place. The Agriculture Department is attempting to get out ahead of this potential problem before it fully takes hold. Experts are quick to point out that the mere presences of the screwworm does not automatically equate to a public health threat as cross species contamination for this parasite is rare. Continued vigilance is encouraged by the USDA as this potential problems is dealt with. Livestock farmers have grown accustomed to hardships in recent years especially those that are outside of their control. The New World screwworm is no exception. They keep careful track of situations like this and are fully prepared for any contingency.
