Avian mycobacteriosis in companion birds: 20-year survey

Avian surfactant protein (SP)-A2 first arose in an early tetrapod before the divergence of amphibians and gradually lost the collagen domain

The air-liquid interface of the mammalian lung is lined with pulmonary surfactants, a mixture of specific proteins and lipids that serve a dual purpose-enabling air-breathing and protection against pathogens. In mammals, surfactant proteins A (SP-A) and D (SP -D) are involved in innate defence of the lung. Birds seem to lack the SP-D gene, but possess SP-A2, an additional SP-A-like gene. Here we investigated the evolution of the SP-A and SP-D genes using computational gene prediction, homology, simulation modelling and phylogeny with published avian and other vertebrate genomes. PCR was used to confirm the identity and expression of SP-A analogues in various tissue homogenates of zebra finch and turkey. In silico analysis confirmed the absence of SP-D-like genes in all 47 published avian genomes. Zebra finch and turkey SP-A1 and SP-A2 sequences, confirmed by PCR of lung homogenates, were compared with sequenced and in silico predicted vertebrate homologs to construct a phylogenetic tree. The collagen domain of avian SP-A1, especially that of zebra finch, was dramatically shorter than that of mammalian SP-A. Amphibian and reptilian genomes also contain avian-like SP-A2 protein sequences with a collagen domain. NCBI Gnomon-predicted avian and alligator SP-A2 proteins all lacked the collagen domain completely. Both avian SP-A1 and SP-A2 sequences form separate clades, which are most closely related to their closest relatives, the alligators. The C-terminal carbohydrate recognition domain (CRD) of zebra finch SP-A1 was structurally almost identical to that of rat SP-A. In fact, the CRD of SP-A is highly conserved among all the vertebrates. Birds retained a truncated version of mammalian type SP-A1 as well as a non-collagenous C-type lectin, designated SP-A2, while losing the large collagenous SP-D lectin, reflecting their evolutionary trajectory towards a unidirectional respiratory system. In the context of zoonotic infections, how these evolutionary changes affect avian pulmonary surface protection is not clear.

A review of avian mycobacteriosis: An emerging bacterial disease of public health concern

Avian mycobacteriosis is a chronic debilitating disease of birds which poses a public health threat. In avian species, the disease is primarily caused by Mycobacterium avium subspecies avium. Nearly all bird species are susceptible to this infection, with older birds being more susceptible than younger ones. Ingestion of feed and water contaminated by the excreta of infected or chronic carrier birds is the main route of Mycobacterium infection and transmission; however, the respiratory route is also possible. Migratory wild or free-living birds play an important role in mycobacteriosis transmission, and affected birds show severe depletion, emaciation, anemia, diarrhea, and respiratory manifestations. The appearance of characteristic tuberculous nodules in the digestive system, especially in the intestine, liver, and spleen, is pathognomonic. Confirmation of Mycobacterium infection can be achieved through isolation on specifically selected media, direct smear for detection of characteristic acid-fast bacilli, and detection of the bacterium using molecular diagnostic methods. Serological and allergic tests can also be applied. Different species of Mycobacterium, especially M. avium, have public health significance and can be transmitted from birds to humans. Such zoonosis is especially dangerous in human immunocompromised patients. Authorities and governments have implemented strict and comprehensive eradication programs for avian mycobacteriosis. These biosecurity measures, including surveillance monitoring programs and antimicrobial susceptibility testing, are essential for the prevention and treatment of Mycobacterium infection in poultry production systems. This review was designed to focus on avian mycobacteriosis in birds and humans.

Mycobacteriosis in Various Pet and Wild Birds from Germany: Pathological Findings, Coinfections, and Characterization of Causative Mycobacteria

A total of 50 birds diagnosed with mycobacteriosis were examined for pathomorphological lesions, coinfections, and causative agents. Mycobacterial species were identified and isolates differentiated using multilocus sequence typing (MLST) and mycobacterial interspersed repetitive-unit variable-number of tandem-repeat (MIRU-VNTR) analysis. Possible associations between mycobacterial species, pathomorphological findings, coinfections, bird orders, and husbandry conditions were evaluated statistically. Mycobacteria were isolated from 34 birds (13 of 22 Psittaciformes, 12 of 18 Passeriformes, five of six Columbiformes, and four other orders) belonging to 26 species in total. Mycobacterium genavense (Mg) was cultured from 15 birds, Mycobacterium avium subsp. avium (Maa) from 20 birds, and Mycobacterium avium subsp. hominissuis (Mah) from three birds; hence, four birds had mixed infections. About equal numbers of psittacines and passerines were infected with Ma and Mg. The genetic diversity differed; Mg isolates belonged to one MLST type, Maa to six, and Mah to three combined genotypes. Several coinfections were detected; viruses and/or endoparasites affected 44%, fungi 38%, and bacteria 29% of the birds. Pathological findings and mycobacteriosis-affected organs were independent of coinfections. Overall, gross pathological findings were more often seen in mycobacteriosis caused by Ma (95%) compared with Mg (66%). Organ distribution of mycobacteriosis was independent of the mycobacterial species. Pathomorphological changes were seen in the small intestine of 71% and the lung of 65% of the birds, suggesting oral or pulmonal ingestion of mycobacteria. There were no associations between mycobacterial species and bird orders or bird husbandry conditions. Not only Mg, but also Maa and Mah, were clearly identified as primary cause of mycobacteriosis in pet birds. IMPORTANCE In this study, the causative agents and confounding factors of mycobacteriosis in a set of pet and some wild birds from Germany were examined. Not only Mycobacterium genavense, but also M. avium subsp. avium and M. avium subsp. hominissuis, contributed to mycobacteriosis in these birds. Various coinfections did not affect the manifestation of mycobacteriosis. Due to different gross necropsy findings, however, a different pathogenicity of the two species was assumed. New strains of M. avium subsp. hominissuis originating from birds were identified and characterized, which is important for epidemiological studies and for understanding the zoonotic role of this pathogen, as the subsp. hominissuis represents an increasing public health concern. The study provides some evidence of correlation between M. avium subsp. avium genotypes and virulence which will have to be confirmed by broader studies.

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

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.

Retrospective Review of Mycobacterial Conjunctivitis in Cockatiels (Nymphicus hollandicus)

The etiologic disease organism responsible for causing mycobacteriosis in avian species is an acid-fast gram-positive bacterium. This bacterium causes granulomatous disease in various internal organs, but in cockatiels (Nymphicus hollandicus) it has been commonly identified within the conjunctival tissues. Twenty-six cases of mycobacterial conjunctivitis in cockatiels were diagnosed through histopathologic assessment of diseased tissue samples, Fite acid-fast staining, and polymerase chain reaction in this retrospective study. Clinicians who saw these cases were contacted, and information was obtained regarding recommended treatment protocols prescribed for the patients, the Mycobacterium species identified, and case outcomes. All patients in this retrospective study had a biopsy performed on the affected conjunctival tissue, and because of the small size of the patients, this excisional biopsy removed the affected tissue in its entirety or significantly debulked the lesion. Of the 26 cases, 10 were lost to follow-up, 4 were euthanatized, 7 died, and 5 were alive at the time this information was submitted for publication.

Mycobacterial Airsacculitis Caused by Mycobacterium fortuitum in a Southern Rockhopper Penguin (Eudyptes chrysocome)

A 21-year-old male southern rockhopper penguin (Eudyptes chrysocome) was presented with a chronic history of intermittently decreased appetite, lethargy, and regurgitation. On the external physical examination, the bird was determined to be in fair-to-thin body condition with the complete blood count and plasma chemistry panel being largely unremarkable. Full-body radiographic images were considered normal, and gastroscopy showed only mild gastritis and duodenitis. The penguin was euthanatized shortly thereafter due to acute onset of respiratory distress. During the gross necropsy examination, the bird had severe airsacculitis with thick, yellow-to-tan, moist granular plaques adhering to the surface of many air sacs, as well as regional contiguous pneumonia. Intralesional acid-fast bacilli were observed in histologic sections of air sac tissue, and polymerase chain reaction of the affected air sacs was positive for Mycobacterium fortuitum. This clinical case study describes mycobacteriosis in a sub-Antarctic penguin and to the best of the authors' knowledge, the first reported isolation of M fortuitum from a penguin.

Cutaneous Mycobacteriosis Caused by Mycobacterium kansasii in a Yellow-naped Amazon Parrot (Amazona auropalliata)

An approximately 25-year-old, female, yellow-naped Amazon parrot (Amazona auropalliata) was evaluated for a chronic, raised, ulcerative mass on the lateral aspect of the left thigh. Histopathology of an excisional biopsy revealed severe, chronic, multifocal-to-coalescing, ulcerated dermal and subcutaneous granulomas. No infectious organisms were observed on Ziehl-Neelsen or Gomori methenamine silver stains. The parrot was treated with oral sulfamethoxazoletrimethoprim and meloxicam. When reexamined 2 weeks later, the biopsy site had healed. Surgical biopsies were resubmitted 14 months after the original presentation due to recurrence of similar ulcerative lesions on the right leg. Histopathology revealed a similar inflammatory pattern, and hematoxylin-eosin, Ziehl-Neelsen, and silver stains on the biopsy samples were all negative. A Fite-Faraco stain revealed rare acid-fast bacilli throughout the lesion. Tissue polymerase chain reaction test was negative for Mycobacterium avium and Mycobacterium genavense. Mycobacterial culture and subsequent genotyping revealed Mycobacterium kansasii. Mycobacterium kansasii is a significant cause of mycobacteriosis in humans and, therefore, should be considered a potential zoonotic organism. This report describes an unusual primary cutaneous presentation of avian mycobacteriosis.

Longitudinal social network analysis of avian mycobacteriosis incidence in a large population of zoo birds

The goal of this study was to evaluate longitudinal patterns of avian mycobacteriosis spread through a social network. Specifically, we wanted to determine whether the patterns of connectivity over time can predict future infections, and whether this pattern can distinguish between different sources of infection. The study population included 13,409 individuals nested in a larger population of birds that were closely monitored in zoological facilities for over 22 years (1992-2014). A retrospective cohort study design and social network connectivity were used to estimate the association between exposure to an infected bird, and development of mycobacteriosis. Avian mycobacteriosis was diagnosed from histopathology and network connectivity was defined by enclosure histories over discrete time periods. Single-variable and multivariable longitudinal, mixed effects logistic regression models examined whether exposure to infected birds, both directly- and indirectly-connected, was associated with development of mycobacteriosis at the next time step. Our adjusted model showed an increased odds of developing mycobacteriosis (odds ratio = 2.15; 95 % CI: 1.48-3.12; p < 0.001) for birds that were directly exposed (i.e., housed in the same aviary) to another infected bird, compared to those with no exposure. Exposure to a positive, indirectly-connected bird at a previous time step was independently associated with an increased risk of mycobacteriosis (odds ratio = 1.56; 95 % CI: 1.11-2.19). This association persisted in adjusted models even when the indirect contacts were housed in distinctly different aviaries and never had contact with the subject of interest or its environment. Adjusted, risk-stratified models further characterized the type of exposure that increased the risk of avian mycobacteriosis. Birds that were exposed in small aviaries were more likely to develop mycobacteriosis than those exposed in larger aviaries and those with no exposure. The lesion distribution and species of the contact (same species versus different species) were also significant predictors of disease risk. Some findings were sensitive to model variation of time divisions and initiation time. Our study shows avian mycobacteriosis spread through the social network in quantifiable and discernable patterns. We provide empirical evidence that a contagious process drives some of the observed infection, but we also show low transmissibility based on sustained patterns of low incidence over time even when large groups of birds are exposed. Targeted risk mitigation efforts based on the characteristics of the exposure may be effective at reducing risk of avian mycobacteriosis while enhancing population sustainability.

Social network analysis and whole-genome sequencing to evaluate disease transmission in a large, dynamic population: A study of avian mycobacteriosis in zoo birds

This study combined a social network analysis and whole-genome sequencing (WGS) to test for general patterns of contagious spread of a mycobacterial infection for which pathways of disease acquisition are not well understood. Our population included 275 cases diagnosed with avian mycobacteriosis that were nested in a source population of 16,430 birds at San Diego Zoo Wildlife Alliance facilities from 1992 through mid-2014. Mycobacteria species were determined using conventional methods and whole genome sequencing (WGS). Mycobacterium avium avium (MAA) and Mycobacterium genavense were the most common species of mycobacteria identified and were present in different proportions across bird taxa. A social network for the birds was constructed from the source population to identify directly and indirectly connected cases during time periods relevant to disease transmission. Associations between network connectivity and genetic similarity of mycobacteria (as determined by clusters of genotypes separated by few single nucleotide polymorphisms, or SNPs) were then evaluated in observed and randomly generated network permutations. Findings showed that some genotypes clustered along pathways of bird connectivity, while others were dispersed throughout the network. The proportion of directly connected birds having a similar mycobacterial genotype was 0.36 and significant (p<0.05). This proportion was higher (0.58) and significant for MAA but not for M. genavense. Evaluations of SNP distributions also showed genotypes of MAA were more related in connected birds than expected by chance; however, no significant patterns of genetic relatedness were identified for M. genavense, although data were sparse. Integrating the WGS analysis of mycobacteria with a social network analysis of their host birds revealed significant genetic clustering along pathways of connectivity, namely for MAA. These findings are consistent with a contagious process occurring in some, but not all, case clusters.

Resolution of a Localized Granuloma Caused by Mycobacterium avium-intracellulare Complex on the Cere of a Bruce's Green Pigeon (Treron waalia)

A 3-year-old female Bruce's green pigeon (Treron waalia) was presented with granulomatous inflammation of the cere and underlying tissues with osteomyelitis and bone proliferation of the dorsal premaxilla. Biopsy and culture revealed the presence of Mycobacterium avium-intracellulare complex, and multi-antimicrobial treatment was initiated with clarithromycin, ethambutol, rifabutin, and enrofloxacin. The cere lesion improved and no evidence of systemic granulomas was observed over 4 months of treatment, although leukocytosis and monocytosis persisted. Five months after discontinuation of antibiotic therapy, the white blood cell count had normalized, but distal beak irregularities and partial recurrence of the mass were present. The bird died 15 months after discontinuation of antibiotic therapy and necropsy revealed no evidence of active mycobacteriosis of the beak or cere. This report documents an unusual clinical presentation of mycobacteriosis, in addition to its successful resolution.

High prevalence of Mycobacterium genavense within flocks of pet birds

Mycobacterium genavense is regarded as the primary cause of mycobacteriosis in psittaciform and passeriform birds, which are commonly kept as pets. In humans, Mycobacterium genavense is especially pathogenic for young, old, pregnant and immunocompromised people (YOPIs). In birds, only few studies, mainly case reports, exist and there is still little e information about occurrence and relevance of this zoonotic pathogen. In this first pilot study concerning the prevalence of Mycobacterium genavense within flocks of naturally infected pet birds, real-time PCR examinations of 170 individual passeriform and psittaciform birds, including commonly kept budgerigars, lovebirds and zebra finches as well as gold finches and weaver finches, were conducted to determine the infection rate in six different aviaries. Antemortem examinations of faeces and cloacal swabs were compared with postmortem examinations of tissue samples to evaluate the reliability of antemortem diagnostics. Additional ophthalmologic examinations were performed to evaluate their diagnostic potential. Molecular examinations for viral co-infections, including circovirus, polyomavirus and adenovirus, were conducted to identify potential risk factors. PCR results revealed a detection prevalence of Mycobacterium genavense in the flocks varying from 3% to 91% based on postmortem testing, while antemortem diagnostics of faecal samples and swabs showed 64% discrepant (false negative) results. Ophthalmologic examinations were not useful in identifying infected birds within the flocks. Viral co-infections, especially with polyomavirus, were common. It has to be assumed that Mycobacterium genavense infections are widespread and underdiagnosed in companion birds. Viral infections might be an important risk factor. There is urgent need to improve antemortem diagnostics.

MYCOBACTERIOSIS IN CAPTIVE PSITTACINES: A BRIEF REVIEW AND CASE SERIES IN COMMON COMPANION SPECIES (ECLECTUS RORATUS, AMAZONA ORATRIX, AND PIONITES MELANOCEPHALA)

In 2015, three psittacines were presented within 30 days, each with differing clinical signs and patient histories. A 13-yr-old male eclectus parrot (Eclectus roratus) was presented for weakness, depression, and acute anorexia. On presentation it was determined to have a heart murmur, severely elevated white blood cell count (93.9 10³/μl) with a left shift (2.8 10³/μl bands), and anemia (30%). Severe hepatomegaly was noted on radiographs, ultrasonography, and computed tomography. A cytological sample of the liver obtained through a fine needle aspirate revealed intracellular acid-fast bacilli identified as Mycobacterium avium. A 20-yr-old female double yellow-headed Amazon parrot (Amazona oratrix) was presented for a 1-mo history of lethargy and weight loss despite a good appetite. The parrot's total white blood cell count was 16.8 10³/μl and the PCV was 35%. Following its death, a necropsy revealed a generalized granulomatous condition that involved the small intestines, lungs, liver, spleen, and medullary cavities of the long bones, with intracellular acid-fast bacilli identified as Mycobacterium genavense. The third case, an 18-mo-old female black-headed caique (Pionites melanocephala), was presented with a 1-day history of lethargy and depression. On presentation, the caique had a heart murmur, distended coelom, palpable thickening of the coelomic organs, and increased lung sounds. Following the caique's death, a complete necropsy revealed mycobacteriosis of the liver, spleen, small intestines, pericardial fat, and bone marrow. The infection was identified as Mycobacterium genavense. The importance of advances in Mycobacterium spp. identification, continued presence of this organism in captive avian populations, difficulty in obtaining a definitive antemortem diagnosis, and conflicting recommendations regarding treatment are thought-provoking areas of focus in this case series.

Respiratory tract infection caused by Mycobacterium bovis in a black swan (Cygnus atratus)

A 3-year-old male black swan (Cygnus atratus), belonging to a private collection, died suddenly and was subjected to post mortem examination. At necropsy, caseous exudate was observed in the lungs and air sacs; granulomatous lesions characterized by epithelioid macrophages and abundant mycobacteria were observed microscopically. Avian tuberculosis associated with Mycobacterium bovis was confirmed by bacteriologic isolation, biochemical tests and molecular methods. The organism was identified as spoligotype SB0140, which is frequently found in cattle and people in North America. In this case, interspecies transmission could have been the source of infection because the swan cohabited with cattle.

IDENTIFICATION OF MYCOBACTERIUM GENAVENSE IN A DIANA MONKEY (CERCOPITHECUS DIANA) BY POLYMERASE CHAIN REACTION AND HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

A 25-yr-old Diana monkey (Cercopithecus diana) with a 1.5-yr history of chronic colitis and diarrhea was found to have disseminated granulomatous disease with intralesional acid fast bacilli. Bacilli were identified as Mycobacterium genavense by polymerase chain reaction, sequencing of the 16S-23S ribosomal RNA intergenic spacer (ITS) gene, and mycolic acid analysis by high-performance liquid chromatography. Mycobacterium genavense is a common cause of mycobacteriosis in free-ranging and captive birds. In addition, recognition of opportunistic infection in human immunodeficiency virus-positive patients is increasing. Disease manifestations of M. genavense are similar to Mycobacterium avium complex (MAC) and include fever, wasting, and diarrhea with disseminated disease. Similar clinical signs and lesions were observed in this monkey. Mycobacterium genavense should be considered as a differential for disseminated mycobacterial disease in nonhuman primates as this agent can mimic MAC and related mycobacteria.

An outbreak of Mycobacterium genavense infection in a flock of captive diamond doves (Geopelia cuneata)

Two diamond doves (Geopelia cuneata) in a flock of 23 birds housed in an aviary in a zoo in central Japan were found dead as a result of mycobacteriosis. Fecal samples of the remaining doves were positive for mycobacterial infection, and thus they were euthanatized. Clinical signs and gross pathology, including weight loss and sudden death and slight enlargement of the liver and intestine, were observed in a small number of birds (3/23). Disseminated histiocytic infiltration of either aggregates or sheets of epithelioid cells containing acid-fast bacilli, in the absence of caseous necrosis, were observed in different organs of the infected doves, especially lungs (23/23), intestines (9/23), livers (7/23), and hearts (6/23). Mycobacterium sp. was isolated from the livers of three birds (3/23). DNA extracted from frozen liver and formalin-fixed, paraffin-embedded tissues (5/23) were used for amplification of the gene encoding mycobacterial 65-kDa heat shock protein (hsp65). The causative Mycobacterium species was identified by PCR-restriction fragment length polymorphism analysis. Mycobacterium genavense infection was confirmed in three of the diamond doves. Moreover, partial 16S rDNA gene sequencing revealed 100% identity across the three samples tested, and 99.77% nucleotide homology of the isolate sequence to M. genavense. The main route of M. genavense infection in the diamond doves was most likely airborne, suggesting a potential zoonotic risk of airborne transmission between humans and birds.

Evaluation of Multidrug Therapy With Azithromycin, Rifampin, and Ethambutol for the Treatment of Mycobacterium avium subsp avium in Ring-neck Doves (Streptopelia risoria): An Uncontrolled Clinical Study

An uncontrolled clinical study was conducted to evaluate the efficacy of a multidrug protocol in 16 ring-neck doves ( Streptopelia risoria ) from a flock naturally infected with Mycobacterium avium subsp avium. The doves were considered infected on the basis of a high prevalence of infection in a group of 29 birds that were euthanatized from the same flock and clinical signs and pathologic results consistent with infection in the remaining birds. All birds were treated with azithromycin (43 mg/kg), rifampin (45 mg/kg), and ethambutol (30 mg/kg) administered orally once daily for 180 days. Five birds died during treatment and were confirmed positive for mycobacteriosis on postmortem examination. Of the remaining 11 birds, infection and disease were present in 9 (81.8%) at the end of the treatment. Postmortem investigation showed that 2 mycobacterial isolates were resistant to ethambutol, intermediately sensitive to rifampin, and sensitive to azithromycin. Microscopic examination of liver sections equivalent of those that would be taken for biopsy showed that biopsy as a method of monitoring birds for treatment success had poor sensitivity. Toxicity associated with drug therapy was not observed in these doves nor in 6 outwardly healthy ring-neck doves exposed to the same treatment. The results of this study showed that this protocol of azithromycin, rifampin, and ethambutol has poor efficacy when administered for 180 days for treatment of doves infected with M avium subsp avium.

Taking a rational approach in the treatment of avian mycobacteriosis

Treatment for avian mycobacteriosis is still in its infancy and based on extrapolations from human medicine. The optimum drug choice, dose, or length of treatment has yet to be determined for most exotic animal species. Treatment should include multiple drugs for extended periods of time with appropriate monitoring of both drug levels and overall animal health. Risk to owners and handlers needs to be minimized through appropriate identification of the species of mycobacteri causing disease. More research is necessary on the pharmacokinetics of these drugs in other animal species and antibiotic resistance. Currently, euthanasia remains the most common action in the face of active mycobacteriosis.

Pathology of mycobacteriosis in birds

Avian mycobacteriosis is a disease that affects companion, captive exotic, wild, and domestic birds. The disease in birds is generally caused by Mycobacterium avium subsp avium but more than 10 other species of mycobacteria infect birds. Oral route of infection appears to be the primary mode of transmission. In some cases, the extensive involvement of the respiratory system suggests an airborne mode of transmission. Molecular diagnostic techniques have improved the ability to confirm the disease. Avian mycobacteriosis is an important veterinary and economic risk in birds and mammals. Exposure of humans to infected birds may cause a zoonotic infection.

Molecular epidemiology of mycobacteriosis in wildlife and pet animals

The ecology of mycobacteria is shifting in accordance with environmental change and new patterns of interaction between wildlife, humans, and nondomestic animals. Infection of vertebrate hosts throughout the world is greater now than ever and includes a growing prevalence in free ranging and captive wild animals. Molecular epidemiologic studies using standardized methods with high discriminatory power are useful for tracking individual cases and outbreaks, identifying reservoirs, and describing patterns of transmission and are used with increasing frequency to characterize disease wildlife. This review describes current features of mycobacteriosis in wildlife species based on traditional descriptive studies and recent molecular applications.

Mycobacterium genavense as a cause of subacute pneumonia in patients with severe cellular immunodeficiency

BACKGROUND

Mycobacterium genavense is a rare nontuberculous mycobacteria (NTM). Human infections are mostly disseminated in the setting of the AIDS epidemic or the use of aggressive immunosuppressive treatments. M. genavense culture is fastidious, requiring supplemented media. Pulmonary involvement rarely occurs as a primary localization.

CASES PRESENTATION

We report here two patients with pneumonia as the predominant manifestation of M. genavense infection: one kidney transplanted patient and one HIV-infected patient. Both patients were initially treated with anti-tuberculous drugs before the identification of M. genavense on sputum or broncho-alveolar lavage fluid culture. A four-drug regimen including clarithromycin and rifabutin was started. Gamma interferon has been helpful in addition to antimycobacterial treatment for one patient.

CONCLUSION

Clinicians should be aware that M. genavense could be the etiologic agent of sub-acute pneumonia mimicking tuberculosis in patients with cellular immunodeficiency status.

Tuberculosis in Birds: Insights into the Mycobacterium avium Infections

Tuberculosis, a List B disease of World Organization for Animal Health, caused by M. avium or M. genavense predominantly affects poultry and pet or captive birds. Clinical manifestations in birds include emaciation, depression and diarrhea along with marked atrophy of breast muscle. Unlike tuberculosis in animals and man, lesions in lungs are rare. Tubercular nodules can be seen in liver, spleen, intestine and bone marrow. Granulomatous lesion without calcification is a prominent feature. The disease is a rarity in organized poultry sector due to improved farm practices, but occurs in zoo aviaries. Molecular techniques like polymerase chain reaction combined with restriction fragment length polymorphism and gene probes aid in rapid identification and characterization of mycobacteria subspecies, and overcome disadvantages of conventional methods which are slow, labour intensive and may at times fail to produce precise results. M. avium subsp. avium with genotype IS901+ and IS1245+ causes infections in animals and human beings too. The bacterium causes sensitivity in cattle to the tuberculin test. The paper discusses in brief the M. avium infection in birds, its importance in a zoonotic perspective, and outlines conventional and novel strategies for its diagnosis, prevention and eradication in domestic/pet birds and humans alike.

Comparative immunological and microbiological aspects of paratuberculosis as a model mycobacterial infection

Paratuberculosis or Johne's disease of livestock, which is caused by Mycobacterium avium subsp. paratuberculosis (MAP), has increased in prevalence and expanded in geographic and host ranges over about 100 years. The slow and progressive spread of MAP reflects its substantial adaptation to its hosts, the technical limitations of diagnosis, the lack of practical therapeutic approaches, the lack of a vaccine that prevents transmission and the complexity and difficulty of the on-farm control strategies needed to prevent infection. More recently evidence has accumulated for an association of MAP with Crohn's disease in humans, adding to the pressure on animal health authorities to take precautions by controlling paratuberculosis. Mycobacterial infections invoke complex immune responses but the essential determinants of virulence and pathogenesis are far from clear. In this review we compare the features of major diseases in humans and animals that are caused by the pathogenic mycobacteria M. ulcerans, M. avium subsp. avium, M. leprae, M. tuberculosis and MAP. We seek to answer key questions: are the common mycobacterial infections of humans and animals useful "models" for each other, or are the differences between them too great to enable meaningful extrapolation? To simplify this, the immunopathogenesis of mycobacterial infections will be defined at cellular, tissue, animal and population levels and the key events at each level will be discussed. Many pathogenic processes are similar between divergent mycobacterial diseases, and at variance between virulent and avirulent isolates of mycobacteria, suggesting that the research on the pathogenesis of one mycobacterial disease will be informative for the others.

Acinetobacter baumannii in Localised Cutaneous Mycobacteriosis in Falcons

Between May 2007 and April 2009, 29 falcons with identically localized, yellowish discolored cutaneous lesions in the thigh and lateral body wall region were presented at Abu Dhabi Falcon Hospital. Out of 18 falcons integrated in this study, 16 tested positive to Mycobacterium. avium complex. The 2 negative falcons tested positive in the Mycobacterium genus PCR. Moreover, 1 falcon tested positive to M. avium. paratuberculosis in tissue samples by PCR. In all cases, blood and fecal samples tested negative. In the acid-fast stain, all samples showed the for mycobacteriosis typical rods. Moreover, in 13 samples Acinetobacter baumannii was detected by PCR and proven by DNA sequencing. Clinical features included highly elevated WBCs, heterophilia, lymphocytopenia, monocytosis, severe anemia and weight loss. A. baumannii, a gram-negative bacillus with the ability to integrate foreign DNA, has emerged as one of the major multidrug resistant bacteria. In veterinary medicine, it has so far been detected in dogs, cats, horses and wild birds. To the authors' knowledge, this is the first report of an A. baumannii infection in falcons and of a veterinary Mycobacterium-Acinetobacter coinfection.