Flesh-eating screwworms are feasting on pets; 4 dogs and cat attacked this week

Pet owners must now be vigilant for unusual wounds on their animals, as screwworm infestations are present in the US.

The New World Screwworm (NWS), a parasitic fly whose larvae feed on living flesh, has re-invaded the United States. Since June, the United States Department of Agriculture (USDA) has identified 74 animal cases across three states: Texas, New Mexico, and most recently, Arizona. This week alone, four dogs and one cat were confirmed to be infected, bringing the total number of pet cases to ten since the infestation began. The flies lay eggs in animal wounds and orifices, and the resulting maggots burrow into and consume the host's tissue. Historically eradicated in the US by the 1960s through sterile male fly releases, the NWS has returned after a biological barrier in the Darién Gap was breached in 2022. While primarily a threat to livestock, the screwworm also affects wildlife and, in rarer instances, humans. Mexico has reported 806 human cases and nine fatalities from the parasite.

The re-emergence of New World Screwworms in the US signifies a potential biological threat to domestic animals and livestock, underscoring the fragility of pest eradication efforts. The breach of the Darién Gap barrier highlights challenges in maintaining biosecurity across international borders, suggesting that previously contained threats could resurface more broadly. This event may lead to increased monitoring and preventative measures along southern US borders and a renewed focus on international cooperation for pest management strategies.

For pet owners and livestock producers, the immediate impact is an increased risk of parasitic infestation that can cause severe, potentially fatal wounds. This necessitates greater vigilance in animal health monitoring and prompt veterinary care for any wounds. The spread also poses economic risks to the agricultural sector and could strain resources for animal health agencies tasked with containment and eradication efforts.