Mexico City, Nov. 25 (Reuters) – The United States has temporarily halted imports of Mexican cattle following the discovery of New World screwworm (NWS) in southern Mexico, the Mexican government confirmed on Sunday. The case was identified in Catazaja, a town in the southern state of Chiapas, near the Guatemalan border.
In a statement, the Mexican government said both countries were working together to implement measures to restore normal trade flows as soon as possible. The suspension, however, only applies to cattle exports, with no impact on other goods.
The U.S. Department of Agriculture (USDA) announced on Friday that Mexico’s chief veterinary officer had notified it of the NWS case, which was detected in a cow at a checkpoint in the region. The USDA explained that NWS larvae infest warm-blooded animals, including livestock and humans, entering through open wounds and feeding on living tissue.
NWS infestations can be challenging to detect early, but symptoms may include the presence of larvae, growing wounds, and signs of discomfort in affected animals. The USDA has urged farmers and producers in the region to closely monitor their livestock and pets for potential signs of infection and report any suspected cases immediately.
In response, the USDA is collaborating with Mexican and Central American authorities to prevent the further spread of the screwworm, a serious threat to animal health in the region.
According to the USDA, the New World screwworm (NWS), ‘Cochliomyia hominivorax’, is a destructive pest that can cause severe, often fatal damage to animals. The larvae (maggots) of the NWS fly burrow into the flesh of living creatures, including livestock, pets, wildlife, and in rare cases, humans. This parasitic infestation is particularly concerning because it can lead to serious health issues and even death for affected animals.
NWS is endemic in parts of the Caribbean, Central America, and South America, including Cuba, Haiti, the Dominican Republic, and several South American countries. Recently, cases have spread northward to Costa Rica, Nicaragua, Honduras, Guatemala, and Mexico. Although the U.S. successfully eradicated NWS in 1966 using a technique called sterile insect release, the threat of reintroduction remains, and the U.S. government continues to monitor the situation.
The USDA’s Animal and Plant Health Inspection Service (APHIS) works in collaboration with Panama to maintain a biological barrier to prevent the spread of NWS into areas free of the pest. Through the Panama-United States Commission for the Eradication and Prevention of Screwworm (COPEG), sterile male screwworm flies are released in Panama’s Darien Province, helping to reduce the local screwworm population.
NWS larvae are particularly dangerous as they feed on living tissue, causing significant harm to their host. The maggots burrow into open wounds, feeding as they go, which can result in growing, painful lesions. In some cases, infestations are not easily detected, but visible signs of the condition may include irritated behavior, head shaking, foul-smelling wounds, or the presence of maggots in an animal’s flesh. These wounds can worsen quickly, causing severe damage.
Screwworm flies, similar in size to a common housefly, are easily recognizable by their metallic blue or green bodies and distinctive orange eyes. The adult flies are capable of laying eggs on open wounds, where the larvae hatch and begin their destructive feeding cycle.
If you suspect that an animal has been infested by screwworms, it is crucial to seek veterinary treatment immediately. For people, those who believe they may have been affected should follow guidelines from the Centers for Disease Control and Prevention (CDC) and seek medical care right away.
To help prevent the spread of NWS, animal owners are encouraged to:
- Be vigilant for symptoms in pets and livestock, especially if traveling internationally from areas where NWS is prevalent.
- Have pets traveling abroad thoroughly inspected for screwworms upon their return.
- Check vehicles for any signs of screwworm flies if in an affected region.
- Report any suspected cases of screwworm infestation immediately to state animal health officials and APHIS. Early detection and rapid response are key to preventing the establishment of the pest in new areas.
Eradicating NWS requires a long-term effort, primarily through the use of sterile insect techniques, which involve releasing sterilized male flies into infested regions. These males mate with fertile females, gradually reducing the population of screwworms until the pest is eliminated.
If you encounter or suspect NWS, act quickly and report it to local authorities to help protect animal health and prevent the spread of this dangerous pest. For more information on New World screwworms and their impact on human and animal health, visit the CDC’s website.
