An epizootic of
toxoplasmosis occurred among 22 adult and 30 kit black-footed ferrets (Mustela nigripes) maintained under quarantine conditions at the Louisville Zoological Garden (Louisville, Kentucky, USA) in June, 1992. Black-footed ferrets appear to be highly susceptible to acute and chronic
toxoplasmosis. Clinical signs were observed in 19 adults and six kits and included
anorexia,
lethargy,
corneal edema, and
ataxia. Two adults and six kits died with
acute disease. High antibody titers to Toxoplasma gondii were detected by
latex agglutination and modified agglutination assay in 10 black-footed ferrets. One adult and six kits that died with acute clinical signs were necropsied and T. gondii-like organisms were found microscopically in multiple organs. Diagnosis of
toxoplasmosis was confirmed by immunohistochemical staining with
anti-T. gondii
antibodies and by ultrastructural examination. Although the source of T. gondii for black-footed ferrets was not identified, frozen uncooked rabbit was the most likely source. Chronic
toxoplasmosis resulted in the death of at additional 13 black-footed ferrets that were adults during the epizootic. Affected animals developed chronic progressive posterior weakness and posterior
ataxia 6-69 mo after the epizootic began.
Meningoencephalitis or meningoencephalomyelitis associated with chronic
toxoplasmosis were identified at necropsy in all 13 ferrets. Precautions to prevent introduction of pathogens into the colony were insufficient to exclude T. gondii. Although
toxoplasmosis may cause significant mortality in mustelids, the high mortality of black-footed ferrets in this epizootic was of concern due to their endangered status. This is the first detailed report of
toxoplasmosis in black-footed ferrets.