In addition to the threat of zoonoses—animal diseases that can spread to humans—there is growing concern over the screwworm infestation in livestock from Central American countries entering Mexico.

This issue has had an unexpected ripple effect at the border, with stricter regulations for pets and companion animals imposed by U.S. health authorities.

Veterinarian Francisco Ayala explained that due to insufficient education and inadequate sanitary controls at Mexico’s borders, the southern border has been neglected, allowing contaminated livestock from countries like Guatemala and El Salvador—where the disease is endemic—to enter.

Animals traveling from various regions exacerbate health and economic issues, halting the export of cattle for fattening, as the U.S. has closed its borders to livestock from Mexico.

The screwworm lays eggs on livestock, and its larvae can severely harm animals and even affect humans in cases of poor hygiene. Moreover, it can lead to zoonotic diseases. Notably, this disease had been eradicated 40 years ago.

“There are now many requirements we must meet as veterinarians recognized by SENASICA (National Service for Agrifood Health, Safety, and Quality) and linked to the United States to issue health certificates, even for pets or any animal traveling from Mexico to the U.S.,” Ayala explained.

As a result, the U.S. has begun requiring stricter measures to prevent rabies cases in dogs and cats.

In addition to vaccinations, pets must now have a microchip, a rabies certificate, and a screwworm-free certification as part of their animal health passport, Ayala noted.