On November 22, the US Division of Agriculture briefly halted the import of cattle from Mexico after a flesh-eating parasite was detected in animals in southern Mexico. Earlier than the invention of cattle screwworm (Cochliomyia hominivorax) at an inspection level within the state of Chiapas, the species had beforehand been eradicated in North America for the reason that finish of the nineteenth century. The US–Mexico border stays closed to cattle and will not reopen till the brand new yr.
The worm is the larva of a metallic blue-green fly that spends the early a part of its life cycle devouring the dwelling flesh of mammals. Infestations will be deadly. Cows are the screwworm’s favourite feast, however the maggots also can feed on different livestock in addition to wildlife and pets. Flies usually lay their eggs close to open wounds, and if the larvae can discover a gap within the pores and skin to deploy their sharp mouth hooks, they may then bury themselves within the animal’s flesh and gorge.
The discovering in Mexico follows the current reappearance of the parasite in Costa Rica, Nicaragua, Honduras, and Guatemala. Within the face of the reemergence of the parasite, Mexico is intensifying sanitary measures—calling for the therapy of wounds in livestock, larvicide baths, and deworming of cattle—and has launched inspection stations just like the one which found the case in Chiapas. However conservationists from the Wildlife Conservation Society and Mexican ranchers warn that the unlawful cattle commerce would be the actual gateway for the illness to enter North America.
Previous to the closure of its border with the US, Mexico’s Nationwide Confederation of Livestock Organizations had known as on the federal government to clamp down on cattle smuggling throughout Mexico’s southern border. The danger from the parasite is nice, and if it turns into established once more, the price of eliminating it in Mexico could be excessive. Disruption of commerce with the US was even be extremely pricey. In 2023 alone, Mexico’s exports of stay cattle and beef to the US had been price $3 billion.
On the Path of the Screwworm
For almost 20 years, Cochliomyia hominivorax had been eradicated from the US all the way down to the Darien Hole in Panama. That was till the summer season of 2023, when Panama detected a spike in infestations in animals inside 300 kilometers of its northern border with Costa Rica, marking the start of the parasite’s reappearance in Central America.
Costa Rica, declared freed from the aggressive parasite in 1999, then documented outbreaks in July 2023. Nicaragua and Honduras, freed from the screwworm since 1996, confirmed circumstances in April and September of this yr respectively. Then in October 2024, Guatemala reported the reemergence of the fly and its larvae, with a calf as its first fatality. The menace to nations additional north is obvious. Based on the Panama–United States Fee for the Eradication and Prevention of Screwworm, as of November 2, these 4 nations had collected 15,638 screwworm circumstances in 2024, together with 20,890 documented in Panama.
In experiences submitted to the World Group for Animal Well being, three of these nations—Costa Rica, Nicaragua, and Honduras—pointed to the unlawful transit of animals because the origin of infections of their territories. Honduras detected an outbreak after inspecting 68 horses that entered the nation illegally, for instance, simply 8 kilometers from its border with Nicaragua.
