Respiratory Infection by Cyathostoma (Hovorkonema) americana in a Population of Burrowing Owls (Athene cunicularia)—A Potential Case of Zoo–Wildlife Cross-Transmission

Abstract

A population of burrowing owls (Athene cunicularia) under professional care at Zoomarine Portugal presented with sudden respiratory clinical signs. Clinical management included a thorough diagnosis plan, including in-house fecal analysis that revealed the presence of ovoid unioperculate eggs. In the postmortem examination of one hyperacute dyspneic specimen, adult nematode parasites were collected and identified based on their morphology as Cyathostoma (Hovorkonema) americana. Even after a broad-spectrum deworming protocol as part of the treatment and metaphylaxis approach, the incidence of parasitic reinfection was high. The complete clinical resolution was only accomplished after the identification and management of the possible focus of infection, a wild population of cattle egrets (Bubulcus ibis) that frequently congregated above the owls’ habitat. To the authors’ best knowledge, this is the first report of infection by Cyathostoma (Hovorkonema) americana in burrowing owls. Although nematodes of the family Syngamidae are not commonly included in the differential diagnosis of infectious respiratory agents of birds of the order Strigiformes, this report highlights the possibility of opportunistic parasitism in a zoological context, especially where there is a continued proximity to free-ranging avifauna.