Upper respiratory tract infection caused by Cryptosporidium baileyi in three mixed-bred falcons (Falco rusticolus x Falco cherrug).

Three mixed-bred raptors (Falco rusticolus x Falco cherrug) from a German falcon breeder were presented with a history of respiratory distress. In one bird a laryngeal stridor was noted, and oral examination revealed an epiglottal swelling. In the other two birds, nasal discharge and sneezing were the main clinical symptoms. Nasal flushing samples and biopsies were collected for pathologic, bacteriologic, and parasitologic examination. Results confirmed a cryptosporidial infection. Polymerase chain reaction (PCR) and DNA analysis identified the causative agent to be Cryptosporidium baileyi. No cryptosporidia were detected in fecal samples, indicating the infection was confined to the respiratory system. Analysis of prey animals (pigeons, quail) failed to identify the source of infection. Treatment was initiated with paromomycin in all three birds, whereas in two birds an additional therapy with azithromycin was given. However, no clinical improvement was seen after several weeks of treatment, and the birds either died or were euthanatized. To the authors' knowledge, these are the first confirmed cases of disease caused by cryptosporidia in the order of Falconiformes.