Health impacts and clinical management of New World Screwworm infestation on dogs and cats in a reintroduction scenario in the United States

Abstract

The New World Screwworm (NWS), Cochliomyia hominivorax, is an obligate myiasis-causing dipteran native to the Americas. Its larval stages voraciously feed on living tissues of a broad range of warm-blooded hosts, including domestic animals, wildlife, and humans. NWS is a parasite of substantial economic importance due to its deleterious effects on livestock health, productivity, and welfare. This led to highly successful eradication efforts from the United States (U.S.), Mexico, and throughout Central America via mass release of sterile males. Nevertheless, the resurgence of cases in Central America and Mexico in recent years, and the current cases diagnosed in Texas and New Mexico, has raised significant concern among U.S. animal health agencies and stakeholders. From a public health perspective, NWS is also noteworthy because human infestations have been reported globally, including in non-endemic regions associated with travel to endemic areas. NWS infestations in companion animals may be influenced by various factors, including ownership status, breed, frequency of animal inspection, and lifestyle, all of which may be associated with a higher propensity for the occurrence of lesions. Depending on the anatomic location of parasitism, the severity of the infestation, and the timeliness of diagnosis and intervention, the infestation may be fatal Current clinical management primarily targets active infestations using agents such as macrocyclic lactones, nitenpyram, or isoxazolines; while preventive medications remain limited. This review provides an overview of the current clinical management of natural NWS infestations in dogs and cats and summarizes the main therapeutic and prophylactic antiparasitic options available in the U.S.