Retrospective Evaluation of Clinical Signs and Gross Pathologic Findings in Birds Infected WithMycobacterium genavense

Abstract

Mycobacterium genavense is regarded as the primary cause of mycobacteriosis in passerine and psittacine birds kept in captivity. Mycobacterium genavense is a potential zoonotic pathogen; therefore, early antemortem detection in birds is needed. In humans, infections with M genavense are found predominantly in immunocompromised people. To investigate clinical signs and pathologic lesions and to determine the prevalence of coinfections in birds infected with M genavense, we reviewed records of 83 birds in which DNA from M genavense had been detected via real-time polymerase chain reaction. To evaluate clinical signs in birds presented as patients, results of standardized examinations of 60 birds and radiographic results from 37 birds were investigated. Necropsy results of 82 of the 83 birds were evaluated, including results of additional parasitologic, bacteriologic, and virologic examinations. Birds included in the study comprised 15 species in the orders Passeriformes, Psittaciformes, Coliiformes, Columbiformes, Coraciiformes, and Ciconiiformes. A wide range of clinical manifestations were documented, including neurologic disorders, ocular manifestations, and gastrointestinal signs. Of the 60 birds examined clinically, 15% showed no clinical signs. Coinfections with a wide range of pathogens were detected in 52% (43 of 83) of the tested birds. Coinfections included Macrorhabdus ornithogaster, circovirus, polyomavirus, avian bornavirus, adenovirus, Mycobacterium avium ssp. avium/ silvaticum, Mycoplasma species, Salmonella species, Escherichia coli, Aspergillus species, and various parasites. The high number of coinfections may reflect an impaired immune status in the birds examined. These results also suggest a broad host range for M genavense, and the existence of various clinical signs that may be strongly associated with coinfections with other pathogens.

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

“…Mycobacteriosis in the examined canaries may have been promoted by immunosuppression caused by the concurrent CaCV and CaPyV infections, as it also may have been by FPyV infection in the Bengalese finch. In a retrospective study conducted by Schmitz et al (31) in birds with mycobacteriosis caused by M. genavense detected post mortem, polyomavirus infection was revealed in 25% and circovirus infection in 35% of cases. However, the birds most susceptible to mycobacteriosis were those infected with both of these viruses.…”

“…Due to the concurrent CaCV and CaPyV infections in canary 4, it is difficult to determine which virus had a greater effect on the loss of feathers on the tail. Schmitz et al (31) suggested a significant effect of polyomavirus on moulting in birds. Typical changes in the blood counts associated with mycobacteriosis are leukocytosis, significant heterophilia and monocytosis (25).…”

“…The faecal-oral route is suspected as the route of infection with M. genavense (19), but the inhalation route cannot be excluded (22,23). An important role in this regard is played by factors promoting the disease, such as immunosuppression caused, inter alia, by viral infections (22,30,31).…”

Domestic parrots as a potential source of Mycobacteriosis

“…Grey parrots are the only birds in which cases of tuberculosis caused by M. tuberculosis and M. bovis are often detected (Schmidt et al, 2008;Washko et al, 1998;Fulton and Sanchez, 2013). The reason for the high prevalence of mycobacterial infections among parrots, especially caused by M. genavense, may be genetic factors, specific susceptibility of species, as well as exogenous causes (housing conditions, congestion, stress, etc.…”

“…silvaticum, Mycoplasma sp., Salmonella sp., Escherichia coli, Aspergillus sp., etc. ), violating the immune status, promote the activation of M. genavense in the host (Schmitz et al, 2018a(Schmitz et al, , 2018bManarolla et al, 2007). www.jvmbbs.kharkov.ua Diagnosis of mycobacteriosis caused by M. genavense is based on the detection of acid-fast rods stained by the method of Ziehl-Neelsen in combination with the culture method on special media for 6-12 weeks (Realini et al, 1999).…”