US cattle threatened by flesh-eating parasitic fly

Cattle in North America are threatened by a flesh-eating parasitic fly which is making its way up from South America and Mexico.

New World screwworm (NWS), Cochliomyia hominivorax, is a devastating pest which can be fatal for livestock, pets and humans, with the larvae burrowing into living flesh.

NWS had previously been eradicated from the US through a combination of chemical treatment of cattle – reportedly at a cost of $750m (£555m) – and cooler weather.

But the pest has recently been detected in Mexico, prompting the US government to launch a five-pronged plan, working closely with Mexico to improve its surveillance and detection of NWS.

With about 14m cattle in Texas and Florida now at risk, an $8.5m (£6.2m) sterile NWS fly dispersal facility is being established at the former Moore Air Force Base at the southern tip of Texas.

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To keep the parasite out, live cattle, horse, and bison imports through US ports of entry along the southern border were suspended on 11 May.

“The United States has defeated NWS before and we will do it again,” said US secretary of agriculture Brooke Rollins.

“We do not take lightly the threat NWS poses to our livestock industry, our economy, and our food supply chain.”

Biological barriers

To further protect livestock, the US Department of Agriculture (USDA) has invested $21m (£15.6m) to renovate an existing fruit fly breeding facility in Metapa, Mexico, which will provide an additional 60m-100m sterile NWS flies a week to create a biological barrier and stop the spread.

This is in addition to the more than 100m a week already produced in Panama, meaning at least 160m flies a week will be released.

National Cattlemen’s Beef Association president Buck Wehrbein said: “The only way to protect the American cattle herd from the devastating threat of New World screwworm is by having a sufficient supply of sterile flies to push this pest away from our border.”