Tracheitis in a broiler chicken flock caused by dual infection with Cryptosporidium spp. (Apicomplexa: Cryptosporiidae) and non-hemolytic Ornithobacterium rhinotracheale.

Broiler chickens aged 41-day-old from a flock of a broiler complex, presenting depression, reduced foo d intake, facial edema, dyspnea, gasping, sneezing, and 5% mortality were studied. At necropsy, opaque thoracic and abdominal air sacs and mucous tracheal content were observed. Hi stopathology of tracheas showed multifocal hyperpla sia of mucosa with a large number of small, round and ovoid basophilic organisms on their surface, which were identified as Cryptosporidium spp. In addition, there was an inflammatory respons e due to infiltration of mononuclear cells and hete rophils in the submucosa. Small pin-point colonies without hemolytic activity were isolated from tracheal samples and identified as Ornithobacterium rhinotracheale by conventional and real time polymerase chain rea ction (PCR). Results of tracheal histopathology, bacteriology, and PCR identificatio n provided the diagnosis of tracheal cryptosporidio sis associated with non-hemolytic O. rhinotracheale secondary infection. This report describes the unu sual dual infection with Cryptosporidium spp. and non-hemolytic O. rhinotracheale causing tracheitis in broiler chickens.