Monitored therapy of sporadic mycobacteriosis caused by Mycobacterium genavense in Atlantic canaries (Serinus canaria) and Bengalese finch (Lonchura striata)

Abstract

Introduction Mycobacteriosis is a significant disease of companion and wild birds which causes emaciation and widely distributed lesions, as well as being a potential zoonosis. Its primary aetiological agents in birds are Mycobacterium avium subsp. avium and the fastidious Mycobacterium genavense. This study monitored the therapy of birds naturally infected with Mycobacterium genavense to gain understanding of its effectiveness and the interrelation of co-infections with the disease course and pharmacotherapy. Material and Methods Five Atlantic canaries (Serinus canaria) and one Bengalese finch (Lonchura striata) with tentative diagnoses of mycobacteriosis resulting from M. genavense infection were treated twice daily with clarithromycin at 40 mg/kg, ethambutol at 30 mg/kg, and moxifloxacin at 10 mg/kg for 6 months. Two canaries were also found to be carriers of Cryptosporidium galli. Mycobacteria in faecal samples of all birds were investigated by bacterioscopy and quantitative PCR. Results Molecular tests yielded positive results for up to four months after treatment initiation for M. genavense and Cryptosporidium, but microscopy failed to detect the latter after four weeks in specimens from one canary. Co-infections with polyomavirus (in all birds) and circovirus and bornavirus (in canaries) were diagnosed. Two birds died during treatment and one was euthanised because of other disease, 1 month after treatment completion. Three canaries were in relatively good health a year after treatment. Conclusion Canary circovirus and polyomavirus co-infection may suppress the immune system and this may facilitate the development of mycobacteriosis. The set of drugs used led to the complete cure of mycobacteriosis in three canaries. In one bird the disease returned. Clarithromycin was the active drug against C. galli. Molecular methods serve well to monitor mycobacteriosis therapy and identify M. genavense and C. galli carriage.

Canary Bornavirus (Orthobornavirus serini) Infections Are Associated with Clinical Symptoms in Common Canaries (Serinus canaria dom.)

“…The relevance of canary bornaviruses as pathogens in common canaries has been unresolved so far. A lack of clinical disease symptoms during observation periods of up to five months in experimental infections of canaries [ 5 , 12 , 20 ] was in contrast to a few case reports of a PDD-like disease in natural infections of single birds [ 12 , 13 , 14 , 15 ]. The investigation presented here, based on a large number of canary patients of a bird clinic, could reveal for the first time, that infections with canary bornavirus are associated with PDD-like disease symptoms in common canaries.…”

“…Avian bornaviruses can, however, be found in a broad range of avian species such as waterfowl [ 9 , 10 ], estrildid finches [ 11 ], and common or domestic canaries, Serinus canaria form. domestica [ 12 , 13 , 14 , 15 , 16 ].…”

“…There are contrastive reports of natural bornavirus infections in canaries which include, at least in a portion of the infected birds, the occurrence of clinical symptoms very similar to PDD in parrots. At present, these reports are limited to a few cases among individual birds kept in Austria, Germany, Poland, Italy, and Brazil [ 12 , 13 , 14 , 15 , 21 , 22 ]. The case report from Austria represented the first description of canary bornaviruses and referred to a canary that had died after a three-day disease with apathy and a dilated proventriculus.…”

“…Circoviruses especially, but also polyomaviruses which frequently infect canaries, might be relevant. Both viruses have been regarded as a cause of immunosuppression in birds and have been frequently detected together with other infectious agents [ 15 , 23 , 24 ].…”