A terrifying flesh-eating parasite that eats animals from the inside out is pouring across the US border from cattle imported from Mexico.
The parasite, commonly called a New World screwworm, was eliminated in North America in the late 19th century, but has made a return as cattle from Panama are being smuggled into the nation.
The US Department of Agriculture (USAD) was alerted about the invasion last month after livestock at the border was infected, warning the parasite could have moved into the nation.
Screwworm larvae are creamy white in color and are deposited on the edge of superficial wounds.
When the eggs hatch, they typically enter the bloodstream through the open wound and will not only infest themselves in livestock, but can also burrow their way into humans.
The Mexican Chief Veterinary Officer notified the US that it had found an infestation in a cow in the southern state of Chiapas during an inspection near the Guatemalan border.
Because it is so difficult to identify screwworm infestations, it is highly likely that infected cattle have crossed into the US – although the USDA has not stated how many may have been impacted.
The USDA has asked cattle producers to monitor their livestock and pets to stop the screwworm’s spread and to immediately report any possible cases.
US Chief Veterinary Officer Dr Rosemary Sifford said that ‘given the northward movement of NWS, APHIS has in recent months stepped up its efforts in Central America to partner with impacted countries to push this pest out of newly affected areas.
‘With this latest find in Mexico, we will further intensify this work to protect American agriculture and reestablish the barrier in Central America.’
The US, Mexico and Central America paid a collective cost of $800 million to completely eradicate the screwworm more than three decades ago, but illegal cattle trafficking has fueled a resurgence.
Screwworms typically don’t travel more than a couple of miles, but the illegal trade of infected cattle has forced the parasite to spread 700 miles from North America’s southern border to Central America’s Pacific coast.
The infestation originated in Nicaragua, passing through Honduras and Guatemala before it spread to Mexico’s livestock.
It reached the US in just two and a half months and has likely spread to American livestock and pets, according to Jeremy Radachowsky, the Wildlife Conservation Society’s Regional Director for Mesoamerica.
‘Evidence directly links illegal cattle trafficking to the screwworm’s resurgence,’ Radachowsky said.
‘By bypassing sanitary controls, often with stressed, undernourished, and injured livestock, cattle smuggling creates the ideal conditions for transboundary transmission of diseases, including brucellosis, tuberculosis, and parasites such as the screwworm.’
The Wildlife Conservation Society (WCS) warned that if the screwworm infestation continues to spread, it ‘could cause catastrophic economic losses, devastate rural economies and trigger a public health crisis.’
If the parasite isn’t eradicated quickly, it could take decades to fully remove the parasite, likely costing American taxpayers billions of dollars, according to WCS.
The disruption of cattle trade will have a costly impact, with the number of incoming beef exports amounting to $3 billion in profit for the US last year alone.
As of November 21, 2024, the number of cattle imports from Mexico to the US amounted to more than 1.2 million – an increase from just over one million last year.
In the wake of the infestation, Mexico authorities have said they’re taking drastic measures to prevent further spread including treating wounds on livestock, deworming cattle and implementing larvicide baths.
These baths are applied through a spray that is used to kill the screwworm larvae before it can transform into a full-fledged parasite.
