On November 22, the USA 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 because the finish of the nineteenth century. The US–Mexico border stays closed to cattle and will not reopen till the brand new 12 months.
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 might be deadly. Cows are the screwworm’s favourite feast, however the maggots can also feed on other livestock in addition to wildlife and pets. Flies typically 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 are going to then bury themselves within the animal’s flesh and gorge.
The discovering in Mexico follows the latest 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 remedy 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 referred to as on the federal government to clamp down on cattle smuggling throughout Mexico’s southern border. The chance from the parasite is nice, and if it turns into established once more, the price of eliminating it in Mexico can be excessive. Disruption of commerce with the US was even be extremely pricey. In 2023 alone, Mexico’s exports of reside cattle and beef to the US had been value $3 billion.
On the Path of the Screwworm
For practically 20 years, Cochliomyia hominivorax had been eradicated from the USA right down to the Darien Hole in Panama. That was till the summer time 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 12 months respectively. Then in October 2024, Guatemala reported the reemergence of the fly and its larvae, with a calf as its first fatality. The risk to international locations additional north is evident. Based on the Panama–United States Fee for the Eradication and Prevention of Screwworm, as of November 2, these 4 international locations had accrued 15,638 screwworm circumstances in 2024, together with 20,890 documented in Panama.
In stories submitted to the World Group for Animal Well being, three of these international locations—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.
