Diseases / List of Bacterial Diseases / Disease description:

Avian Tuberculosis in Waterfowl, Cranes, Lagomorphs and Ferrets (with notes on Hedgehogs)

Large granuloma in a crane with avian tuberculosis. Click here for full-page view with caption. Large granuloma, sectioned. Click here for full-page view with caption.

INFORMATION AVAILABLE

GENERAL INFORMATION

CLINICAL CHARACTERISTICS & PATHOLOGY

INVESTIGATION & DIAGNOSIS

TREATMENT & CONTROL

SUSCEPTIBILITY & TRANSMISSION

ENVIRONMENT & GEOGRAPHY

 

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General and References

Disease Summary

WATERFOWL A chronic debilitating bacterial disease.
CRANES A chronic, insidious, debilitating disease
LAGOMORPHS A severe, fatal disease in captive Brachylagus idahoensis - Pygmy rabbits; very rare in domestic rabbits.
FERRETS Occasionally seen as a clinical disease in pet ferrets.

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Alternative Names (Synonyms)

  • Avian TB
  • Mycobacteriosis
  • Tuberculosis
  • TB

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Disease Type

 Bacterial Infection

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Infectious/Non-Infectious Agent associated with the Disease

  • Mycobacteria of the Mycobacterium-intracellulare avium complex . (Species included within the complex which affect birds and common synonyms: MAIC, Mycobacterium avium complex (MAC), MAI Complex, Mycobacterium avium- Mycobacterium intracellulare Complex, Mycobacterium avium, Avian tubercle bacillus; Mycobacterium intracellulare; Battey bacillus Nocardia intracellularis, Mycobacterium intracellularis)
  • Mycobacterium avium (serotypes 1, 2 and 3) are the major causes of disease in birds (B15).

Infective "Taxa"

Non-infective agents

--

Physical agents

-- Indirect / Secondary

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References

Disease Author

Dr Debra Bourne MA VetMB PhD MRCVS (V.w5)
Click image for main Reference Section

Major References / Reviews

Code and Title List

B10.26.w10, B11.39.w7, B13.46.w1, B14, B15, B32.7.w3, B36.8.w8, B37.x.w1, B47, B48.10.w10
J2.30.w1
J5.33.w1
J6.19.w1, J6.22.w3
J7.11.w2, J7.32.w1, J7.34.w1, J7.40.w3, J7.43.w3
J44.72.w1
J8.17.w1
P3.1990-1991.w1
P4.1992.w1, P4.1993.w4
P16.1993.w1
Th2
V.w4

Cranes:
B115.8.w4, B214.3.28.w19
J1.13.w12, J1.22.w9, J311.21.w1
P1.1991.w9, P36.1994.w8, P62.12.w1, P87.7.w9, P92.1.w4

Lagomorphs:
J2.37.w3, J42.26.w1, J212.1.w1, P3.2006b.w4

Ferrets:
B627.14.w14
J4
.204.w2, J42.123.w1, J212.18.w2, J215.23.w1, J238.132.w2

Other References

Code and Title List

B39.w1
J3.140.w3
J4.99.w1
J5.20.w4, J5.40.w2
J7.5.w1, J7.6.w1, J7.9.w1, J7.12.w2, J7.25.w1, J7.30.w2, J7.30.w4, J7.33.w2, J7.33.w3, J7.43.w1, J7.43.w2
J14.19.w1
J18.39.w1
J29.6.w1
J36.41.w1, J36.44.w1

Hedgehogs:
J3
.114.w7
J10.43.w1
J21
.22.w2

Cranes:
B485.22.w22
J1.47.w5, J40.52.w2

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Clinical Characteristics and Pathology

Detailed Clinical and Pathological Characteristics

General

BIRDS Avian tuberculosis is a chronic, insidious, debilitating disease, generally seen in individual birds rather than in epizootics, and characterized by numerous caseous lesions, particularly in the liver.
HEDGEHOGS Hedgehogs (Erinaceus europaeus - West European Hedgehog) have been demonstrated to carry acid-fact organisms, sometime definitively typed as Mycobacterium avium-intracellulare complex, however no clinical disease has been described associated with the isolations. (J3.114.w7, J21.22.w2)
LAGOMORPHS A fatal disease of captive Brachylagus idahoensis - Pygmy rabbit. and occasionally of Oryctolagus cuniculus domesticus - Domestic rabbit. (J2.37.w3, J42.26.w1, , J212.1.w1, P3.2006b.w4)
FERRETS Usually localised lesions, but sometimes fatal disease.

Clinical Characteristics

BIRDS
  • Early in infection, no clinical signs.
  • Weight loss, muscle atrophy particularly seen as increased prominence of the keel.
  • Occasionally oral plaques.
  • Occasionally lameness (arthritis and osteomyelitis)

(P1.1975.w3)

  • Often only non-specfic signs such as weight loss and anorexia. (J4.169.w6)
  • Emaciation and lameness late in infection. (B214.3.28.w19)
WATERFOWL
  • Clinical signs are not pathognomonic.
  • Usually loss of condition leading to eventual emaciation, with wasting of the pectoral muscles very evident (prominent sternum or keel).
  • Weakness, lameness, diarrhoea and deterioration of the plumage may be noted, including retarded moult.
  • Abdominal distention (usually due to ascites) in advanced disease.
  • Rarely, skin lesions - abscess or nodular growth near eyes, sides of face, base of the bill, wing joints or on legs.
  • Clinical signs of tuberculosis are rarely described in wild waterfowl.

(B10.26.w10, B11.39.w7, B13.46.w1, B14, B15, B36.8.w8, B37.x.w1, P4.1992.w1)

CRANES
  • Clinical signs are variable. (P92.1.w4)
  • Infected birds may not show any clinical signs. (P92.1.w4)
  • Weight loss, prominent keel, anorexia, enlargement of abdominal organs. (B115.8.w4, P36.1994.w8, )
    • Weight loss in a crane which is still eating is suggestive. (P62.12.w1)
    • Debility. (J311.21.w1, P36.1994.w8)
    • Palpation may reveal the presence of one or more abdominal masses. (J311.21.w1, P36.1994.w8, P98.1998.w1)
    • Radiography of the body cavity may reveal the presence of masses. (B115.8.w4, P36.1994.w8, P62.12.w1)
    • WBC is often elevated, with an elevated monocyte percentage. (B115.8.w4, J311.21.w1, P62.12.w1)
    • May be anaemic. (J311.21.w1)
  • In a wild Grus americana - Whooping crane, and a captive Grus rubicunda - Brolga, a mass, granulomatous or ulcerating, protruding from the cloaca. (P36.1994.w8, P98.1998.w1)
    • In the Grus rubicunda - Brolga, histopathological analysis of a biopsy from a cloacal mass revealed a mycobacterial granuloma. (P98.1998.w1)
  • In a free-living Grus americana - Whooping crane from the experimental Rocky Mountain flock, debilitation, weight loss (thin, weight 5.78 kg) and a chronic cloacal prolapse; there was also a large, easily-palpable mid-coelomic mass. (P87.7.w9)
  In Brachylagus idahoensis - Pygmy rabbit 
  • Non-specific signs - weight loss (64%) lethargy (50%), soiling of the perineum (39%), anorexia (32%); other signs less commonly (e.g. lameness in 14%), pale mucous membranes; in three nonpregnant females, lactation (11%). (J2.37.w3)
  • Clinical pathology:
    • Abnormal complete blood cell counts seen in 91% of affected rabbits at some stage of the illness: heterophilia (most common), leucocytosis, monocytosis (29% of samples), anaemia (38% of rabbits - normocytic normochromic nonregenerative or macrocytic hypochromic regenerative), nucleated red blood cells in peripheral blood smears in six rabbits, metamyelocytes in one rabbit. Gneerally, rabbits exhibeted more than one haematological abnormality. (J2.37.w3)
    • In about half of tests, hypoalbuminaemia and/or hyperglobulinaemia. Less often hypercholesterolaemia and azotaemia. Elevated alkaline phosphatase in one individual with osteomyelitis. (J2.37.w3)

In Oryctolagus cuniculus domesticus - Domestic rabbit

  • Illness in two rabbits (Belgian hare and Dutch breeds); one (Dutch breed) with observed weight loss. (J42.26.w1)
  • Deaths of rabbits reported. (J212.1.w1)
  • Chronic (one year when first seen) nasal discharge and violent sneezing. (P3.2006b.w4)
    • A large mass was visible on endoscopic examination of the nasal passages. (P3.2006b.w4)

 

 
  • In a pet ferret, intermittent anorexia, diarrhoea and vomiting over a period of six weeks, continuing through another three weeks of supportive care. (J4.204.w2)
  • In a six-year-old neutered male ferret with concurrent lymphoma, weight loss. (J212.18.w2)
  • In ferrets experimentally infected by the oral route, initial weight loss in the first four weeks post infection, but then weight was regained. (J42.123.w1)

 

Incubation

WATERFOWL Chronic disease (B11.39.w7).
CRANES --
LAGOMORPHS
FERRETS
  • In one pet ferret, clinical signs resumed eight months after initial resection of a jejunal lesion. (J4.204.w2)
  • In experimentally infected ferrets, signs (weight loss) were seen in the first four weeks after infection. (J42.123.w1)

Mortality / Morbidity

WATERFOWL Low in wild birds (e.g. recognised in 9/3000 (0.3%) waterfowl examined in one study J4.99.w1); can be very high in waterfowl collections (B11.39.w7).
CRANES
  • Infection is commonly reported in captive cranes. (B115.8.w4)
  • May be responsible for as much as 10-12% of mortality in cranes in zoos. (B214.3.28.w19)
  • This is a significant problem in both wild and captive Grus americana - Whooping crane and Grus canadensis - Sandhill crane in the USA. (P62.12.w1)
  • In 167 wild Grus grus - Common crane in Germany, 1998-2008, mycobacteriosis was diagnosed as the cause of death in two birds (1.2%), both subadult females, and was found in another crane which died following collision with a power line. [2011] (J1.47.w5)
LAGOMORPHS
  • In Brachylagus idahoensis - Pygmy rabbit: in captive pygmy rabbits, this has been the most common cause of death - 28 deaths (28% of the adult captive population) compared with 18 deaths of adults from other causes, June 2002 - September 2004. (J2.37.w3)
  • Reported very rarely as a spontaneous disease in individual Oryctolagus cuniculus domesticus - Domestic rabbit. (J212.1.w1, P3.2006b.w4)
    • On one farm, 20 adult rabbits and about 40 kits died over a short period. Infection was confirmed in the single rabbit necropsied. (J212.1.w1)
FERRETS
  • Reported most commonly in the past from laboratory ferrets in Europe (including UK), also from farms in New Zealand. (B627.14.w14)
  • A six-year-old neutered male ferret with concurrent lymphoma was euthanised. (J212.18.w1)
  • This is more common in [pet] ferrets than is Mammalian Tuberculosis. (B660.41.w41)

Pathology

BIRDS Gross pathology:
  • General: Usually emaciated, with marked muscle wasting, a prominent keel and absence of fat stores. (P1.1975.w3)
  • GIT: pinpoint to several centimetre diameter yellowish-white nodules. (P1.1975.w3)
  • Hepatic: pinpoint to several centimetre diameter yellowish-white nodules. (P1.1975.w3)
  • Splenic: pinpoint to several centimetre diameter yellowish-white nodules. (P1.1975.w3)
  • Respiratory: lesions are often found in the lungs and air sacs. (P1.1975.w3)
  • Other organs: lesions are often present in bone, but may also be found in other organs, such as the heart. (P1.1975.w3)
  • Lymph nodes: lesions in regional lymph nodes associated with infected organs. (P1.1975.w3)

Histopathology:

  • Variable, "from noncaseous histiocytic granulomas containing sheets of large histiocytes to more traditional granulomas with lymphocytes, epitheliod cells, and several types of giant cells." (P1.1975.w3)
WATERFOWL Gross Pathology:
  • Emaciated. Prominent sternum (keel). Sometimes large volumes of ascitic fluid.
  • Multiple nodules, yellow, white or grey, may be less than 1mm or up to several centimeters in diameter, solid to soft or crumbly in texture. Centre usually caseous in older lesions. Occur most frequently in the liver, but also commonly in the intestines, spleen and less frequently the lung, and may be found in other organs.
  • Liver and spleen may also be enlarged and fragile, with tan-to-green translucent appearance due to amyloid deposition. Occasionally liver and spleen may be large, pale and firm (B36.8.w8).
  • Pericarditis and airsacculitis may be noted. "grape-like" clusters of tubercles have been described on the serous membranes of the thorax (B48.10.w10).
  • Endocarditis, aortic arteritis, skeletal and skin lesions have been noted infrequently.
  • Amyloidosis may be found, developing secondary to the chronic infection (B39.w1).

Histopathology:

  • Recent lesions: mass of histocytic cells with variable numbers of lymphocytes. Later centre of lesion becomes an amorphous eosinophilic mass, with surrounding epithelioid cells and giant cells, with an outer layer of fibrous tissue in older lesions (less fibrosis usual in waterfowl than in some other bird species).

(J7.11.w2, J8.17.w1, B10.26.w10, B11.39.w7, B14, B15, B36.8.w8, B37.x.w1, B48.10.w10).

Unusual Presentations of the Disease:

  • An unusual form of the disease has been described which resembled Amyloidosis, with ascites, an enlarged, pale, firm liver and spleen, sometimes with multiple 1-2 mm foci in the liver, and sometimes hydropericardium. Large amounts of pale amorphous eosinophilic material replaced the normal tissue and inflammatory cells including lymphocytes and large phagocytic cells were found within this (B15).
  • Polycystic liver lesions with a greatly enlarged liver have also been reported as an unusual form of the disease (J5.33.w1).
CRANES Gross Pathology
  • White, cheesy nodules (granulomas) in one or more organs. (P62.12.w1, P62.12.w1)
    • Typically in the gastro-intestinal tract, liver and spleen. (P62.12.w1, P92.1.w4)
    • Granulomas vary in size from 1-5 mm to 100 mm diameter. (P62.12.w1)
    • Mature lesions are characterised by caseous necrosis. (P92.1.w4)
  • In a wild Grus canadensis - Sandhill crane shot in Alaska in 1973. (J1.13.w12)
    • Hepatic: In the liver, "grossly visible tuberculosis-like lesions measuring up to 1 cm." (J1.13.w12)
  • In a wild Grus canadensis - Sandhill crane shot in New Mexico. (D443)
    • Hepatic: Multiple large white nodules "characteristic of tuberculosis lesions". (D443)
    • GIT: In the small intestines, multiple large white nodules "characteristic of tuberculosis lesions". (D443)
  • In a wild Grus americana - Whooping crane found dead near Monte Vista National Wildlife Refuge, Rio Grande County, Colorado. (J1.22.w9)
    • General: Severe atrophy of pectoral muscles, absence of subcutaneous and mesenteric fat.
    • GIT: 
      • Along the small intestine, four clusters of caseous nodules, 2-10 mm diameter, white to cream, partially occluding the intestinal lumen.
      • Between the proventriculus and ventriculus, a crateriform ulcer, 20 mm diameter, firm, with a central caseonecrotic area, partially hollowed and impacted with vegetation.
    • Hepatic: Liver enlarged, containing numerous caseous nodules, 2-3 mm diameter, white to cream, throughout the parenchyma.
    • Splenic: Enlarged, containing many coalescing casous 2-10 mm nodules.
    • Renal: Caseous nodules in the kidneys.
    • Adrenal: Enlarged, light yellow in colour.
    • Respiratory: Caseous nodules on the serosal surface of the trachea.
    • Oral: Near the epiglottis, on the dorsal aspect of the oral cavity, a 10-15 mm diameter caseonecrotic plaque.
    • Impression smears: Acid-fast bacilli present in all caseous lesions. 

    (J1.22.w9)

  • In a captive Grus rubicunda - Brolga: (P98.1998.w1)
    • Hepatic: Multiple granulomas in the liver.
    • GIT: Multiple granulomas in the gizzard wall.
    • Abdomen: one large 6-7 cm long granulomatous mass, and granulomas "scattered throughout the abdomen." (P98.1998.w1)

Histopathology

  • In a wild Grus canadensis - Sandhill crane shot in Alaska in 1973. (J1.13.w12)
    • Hepatic: Granulomas with caseous necrotic centres and a thick encapsulating wall of fibrous connective tissue and epithelioid cells. Within the fibrous capsule a zone of epitheliod cells and vacuolar structures, some filled with clear yellow droplets, apparently lipid, was present. Near the large tubercles, numerous microscopic granulomas. (J1.13.w12)
    • Mycobacterium avium serotype 1 was isolated (nonchromogenic slowly growing acid-fast bacilli). (J1.13.w12)
  • In a wild Grus americana - Whooping crane found dead near Monte Vista National Wildlife Refuge, Rio Grande County, Colorado. (J1.22.w9)
    • Hepatic, splenic, intestinal and tracheal: Typical granulomatous tubules, with central caseous debris, throughout which were vacuoles conatining numerous acid-fast bacilli. No giant cells were found. Some granulomas were surrounded by a thin fibrous capsule. (J1.22.w9)
    • Hepatic: Also small areas of focal necrosis associated with nonacid-fast bacilli. (J1.22.w9)
      • Salmonela enteritidis serotype agona. (J1.22.w9)
    • Oropharyngeal lesion: Streptococcus fecalis, Streptococus sanguis, Streptococcus morbillorum and Staphylococcus sp. were isolated from the lesion.(J1.22.w9)
    • Growth of mycobacteria: From liver and spleen lesions collected in a saturated sodium borate solution. A nonphotochromogenic, slowly growing acid-fast isolate was obtained and confirmed as Mycobacterium avium serovar 1. (J1.22.w9)
  • In a captive Grus rubicunda - Brolga: (P98.1998.w1)
    • Multiple granulomas, surrounded by giant cells and with "central fibrinoid coagulum with some cleft spaces." In the gizzard, granulomas contained masses of degenerate neutrophils, and the central debris contained obvious bacterial colonies.(P98.1998.w1)
    • Impression smeares revealed low numbers of acid-fast bacilli.
    • Ziehl Neelsen staining of tissues revealed many acid-fast bacilli in gizzard lesions, few in liver lesions.
    • Culture: Mycobacterium avium complex and Mycobacterium scrofulaceum complex bacteria were isolated. 
  • In three wild Grus grus - Common crane in Germany, 1998-2008, multiple granulomas containing acid-fast coccoid rods, in the liver, spleen, kidney and GIT.[2011] (J1.47.w5)
LAGOMORPHS In Brachylagus idahoensis - Pygmy rabbit 

Gross pathology:

  • Granulomas in a variety of tissues. These were generally yellow, slightly firmer than normal fat and up to several millimetres in diameter.
  • Note: 
    • There was no correlation between the number/size of lesions detected at necropsy and the clinical state (degree of debilitation) of the animal. For example, pulmonary disease was rarely diagnosed in life but gross lesions were found in the lungs of 18 rabbits. (J2.37.w3)
  • No granuloma formation in one wild-caught (captive 17 months) Idaho pygmy rabbit. (J2.37.w3)

Histopathology:

  • Granulomas detected in 19 tissues. (J2.37.w3)
  • Present in liver and kidney in more than 50%. Pulmonary lesions in 27 rabbits. Lesions were "granulomatous inflammation, discrete granulomas, and areas of necrosis. Inflammation was predominantly comprised of macrophages with fewer neutrophils, lymphocytes and plasma cells, sometimes organised into discrete granulomas oriented around foci of caseous necrosis." There were occasional Langhans-type multinucleate giant cells at the margin of necrotic areas and inflammation. With Fite's acid-fast stain, acid-fast bacilli were detected in low to moderate numbers in necrotic foci and were sometimes seen in the cytoplasm of multinucleate cells or macrophages. (J2.37.w3)
  • No histologically detectable granuloma formation in one wild-caught (captive 17 months) Idaho pygmy rabbit, but necropsy tissues were positive for Mycobacterium avium. (J2.37.w3)

In Oryctolagus cuniculus domesticus - Domestic rabbit

Gross pathology
In one rabbit (Belgian hare breed): 
  • Lungs: numerous small caseous tubercles. (J42.26.w1)
  • Liver: numerous small caseous tubercles. (J42.26.w1)
  • GIT: Small tuberculous nodules throughout the small intestine, reaching the size of a small pea in the duodenum. In the caudal jejunum, large ulcers. In the large intestine, "about half a dozen of the little pouches which are normally present were greatly dilated and covered externally with copious tufts of villous growth. Internally the mucous membrane lining these dilatations was ulcerated, and some of them contained an incarcerated faecal pellet." Vermiform appendix mottled and containing caseous patches, most visible from the serosal side. (J42.26.w1)
  • Lymph nodes: mesenteric lymph nodes contained superficial caseous foci.(J42.26.w1)
  • Spleen: Single small caseous focus.(J42.26.w1)
  • Kidneys: whitish tubercles projecting prominently from the serosal surface. (J42.26.w1)

In one rabbit (Dutch breed):

  • Joints: Right stifle, elbow and tibio-tarsal joint and left hock joint. Synovial membrane yellow, swollen, protruding between the tendons. (J42.26.w1)
  • Lymph nodes: Enlarged popliteal and right axillary lymph nodes but no obvious lesions.

In one adult rabbit examined following deaths of 20 adults and 40 kits on a farm:

  • General: cachexia, severe muscle atrophy. (J212.1.w1)
  • Lungs: in the parencyma and on the serosal surface, white nodules. (J212.1.w1)
  • Liver: in the parencyma and on the serosal surface, white nodules. (J212.1.w1)
  • Kidney: in the parencyma and on the serosal surface, white nodules. (J212.1.w1)
  • Mesentry: white nodules. (J212.1.w1)
  • Intestines: in all layers, white nodules. (J212.1.w1)
  • CNS: 
    • In the cerebrum, white nodules, one 1 mm diameter, the other 3 mm diameter with a localised area of haemorrhage nearby in the leptomeninges. (J212.1.w1)
    • In the medulla oblongata, a 1 mm nodule. (J212.1.w1)
Histopathology

In one rabbit (Belgian hare breed): (J42.26.w1)

  • "Tubercle bacilli were fairly numerous in the lungs and kidneys." (J42.26.w1)
    • Bacilli cultured from kidney lesions and confirmed as Mycobacterium avium. (J42.26.w1)

In one rabbit (Dutch breed):

  • Joints: In the swollen synovial membranes, small numbers of bacilli. (J42.26.w1)
    • Bacilli cultured from the affected knee joint and confirmed as Mycobacterium avium. (J42.26.w1)

In one adult rabbit examined following deaths of 20 adults and 40 kits on a farm:

  • Lung, liver, kidney, intestine: multiple granulomas, generally with central caseous necrosis (sometimes with slight calcification) surrounded by variable zones of infiltrating lymphocytes, epithelioid macrophages, and multinucleated giant cells, with proliferating fibrous connective tissue around the lesions. (J212.1.w1)
  • CNS: 
    • In the cerebrum, two granulomatous lesions, focal, with central necrosis, slight mineralisation of the larger lesions, and numerous lymphocytes. The necrotic zone was encircled by a thin zone of epithelioid macrophages and lymphocytes and there were also small collections of lymphocytes and epithelioid macrophages in the affected gyrus, lymphocytic perivascular cuffs of several vessels, and in the adjacent leptomeninges, focal thickening with epithelioid macrophages and lymphocytes. (J212.1.w1)
    • In the medulla oblongata, a granuloma with central caseous necrosis and numerous lymphocytes, encircled by a thin zone of epithelioid macrophages; lymphocytic perivascular cuffs were present around nearby vessels. (J212.1.w1)
  • Acid-fast bacilli demonstrated by auramine-stain in cerebrum, medulla oblongata, lung, liver, kidney, and intestinal lesions. (J212.1.w1)

In a pet rabbit with respiratory signs (violent sneezing):

  • Mass in nasal passageways was sown on histopathology (following aggressive debridement) to be granulomatous, with acid-fast oragnisms. (P3.2006b.w4)
  • Mycobacterium avium complex cultured. (P3.2006b.w4)
FERRETS
Gross pathology

In a pet ferret: (J4.204.w2)

  • GIT: 
    • Initial lesion removed at surgery: 1 cm constricting band in the jejunum. (J4.204.w2)
    • Pyloric mass, 1 cm diameter, projecting into the gastric lumen, eight months later. At necropsy two weeks after that was resected, thickened pylorus. (J4.204.w2)

In a six-year-old neutered male ferret with concurrent lymphoma. (J212.18.w2)

  • GIT: Stomach wall thickened (2 mm thick) causing the mucosa to form folds. (J212.18.w2)
  • Hepatic: multiple tan 0.5-1.0 cm masses. (J212.18.w2)
  • Mesenteric lymph nodes: enlarged to twice normal size; no obvious cortex-medulla boundary. (J212.18.w2) 

In ferrets experimentally infected by the oral route, no gross lesions. (J42.123.w1)

Histopathology

In a pet ferret: (J4.204.w2)

  • GIT: pylorus: submucosa and lamina propria, sheets of macrophages present. Jejunum and stomach, severe granulomatous inflammation. (J4.204.w2)
  • Lymph nodes: mesenteric, severe granulomatous inflammation. (J4.204.w2)
  • Hepatic: small granulomas present. (J4.204.w2)
  • Splenic: small granulomas present. (J4.204.w2)
  • Acid-fast staining: acid fast bacilli detected. (J4.204.w2)

In a six-year-old neutered male ferret with concurrent lymphoma. (J212.18.w2)

  • GIT: Stomach wall normal mural architecture obliterated by mixed neoplastic lymphocytes (30-50 um diameter round cells with marked anocytosis, large, oval irregular nuclei, moderate eosinophilic cytoplasm, moderate mitotic figures) and granulomatous inflammation (macrophages with abundant, lightly eosinophilic cytoplasm, containing numerous acid-fast bacilli). (J212.18.w2)
  • Hepatic: mixed neoplastic lymphocytes and granulomatous inflammation (macrophages with abundant, lightly eosinophilic cytoplasm, containing numerous acid-fast bacilli). (J212.18.w2)
  • Mesenteric lymph nodes: mixed neoplastic lymphocytes and granulomatous inflammation (macrophages with abundant, lightly eosinophilic cytoplasm, containing numerous acid-fast bacilli). (J212.18.w2)
  • Renal: in the cortex and pelvis, a few small aggregates of macrophages, containing acid-fast bacilli. (J212.18.w1)
  • Pulmonary: In alveolar macrophages, acid-fast bacilli present. (J212.18.w2)
  • PCR: positive for Mycobacterium avium; negative for Mycobacterium bovis and for Mycobacterium avium subsp. paratuberculosis. (J212.18.w2)

In ferrets experimentally infected by the oral route: (J42.123.w1)

  • Mesenteric lymph node: In 1/9 ferrets, microscopic lesions but no detectable acid-fast bacilli with Ziehl-Neelsen staining in any of the ferrets (in contrast to those infected with Mycobacterium bovis, in which 9/9  had microscopic lesions and AFB were found in 8/9). (J42.123.w1)

 

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Human Health Considerations

Humans are considered relatively resistant to bacteria of the Mycobacterium avium-intracellulare complex associated with Avian Tuberculosis of birds; however infections do occur and this is an important opportunistic pathogen of people with HIV or otherwise immunosuppressed (Th2, B32.7.w3, B36.8.w8, P62.12.w1). 
  • In addition to immunocompromise, individuals with existing lung pathology are more susceptible. (P24.334.w4)
  • Transmission to humans is by ingestion or inhalation. (P24.327.w4)
    • Human infection may occur by kissing of, or close contact with, infected birds, such that sufficient numbers of infective organisms are inhaled or ingested. (P24.334.w4)
  • In males over 40 years old, pulmonary chronic cavity tuberculosis may be seen, in children, cervical lympadenitis. Systemic lymphogenic disease can occur. (B12.22.w13)
  • Infections in humans tend to be progressive, refractory to treatment and are often fatal. (B12.22.w13, B47)
    • Cervical lymphadenopaty in children may be treated by surgical excision of the affected lymph node. (B12.22.w13)

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Susceptibility / Transmission

General information on Susceptibility / Transmission

BIRDS Susceptibility:
  • Mortality of infected birds may be seen associated with handling, heat stress (hot, humid weather) or other stressors. (P1.1975.w3)
WATERFOWL Transmission:
  • Usually ingestion of bacilli in contaminated food, water and environment, also inhalation and direct contact. Infected birds can shed large numbers of bacilli in their faeces, with excretion of bacilli occurring in advance of obvious illness. Wastewater discharges, sewage effluents and manure-spreading may contaminate the environment for free-living or captive waterfowl. Transmission between domestic/captive and wild birds probably occurs (B11.39.w7, B15, B36.8.w8).

Susceptibility:

  • All species of birds are susceptible to M. avium infection. Ducks and swans show a higher incidence than geese, and dabbling or diving species are affected more than species that mainly graze on land; this is probably related to higher rates of exposure in species feeding mainly in and around water. (J6.22.w3, J7.34.w1, J44.72.w1, P3.1990-1991.w1, B11.39.w7).
  • Species normally from environments that may have low contamination with mycobacteria, such as seaducks and perching ducks, may be more susceptible, and this susceptibility may have a genetic basis, due to decreased evolutionary pressure to develop resistance. However, genetic variation may be found even within such a group, such as the apparent relative resistance of eider ducks in comparison to the greater susceptibility of mergansers, scoters and goldeneyes. (J7.32.w1, J7.43.w3, J44.72.w1, P3.1990-1991.w1, B11.39.w7).
  • Susceptibility is increased by physiological and environmental stressors, including reproduction, poor nutritional status, poor ventilation, overcrowding, general poor management and hygiene. Pinioning may exert a stress effect by preventing the normal flight response in response to danger in some species (J7.43.w3, J44.72.w1, B11.39.w7, B36.8.w8).
  • Clinical disease is usually seen in older birds, due to the time taken for the disease to develop; disease in a young bird may indicate the individual is immunocompromised (B11.39.w7).

 

CRANES
  • Cranes may be among the more susceptible bird groups. (B115.8.w4)
  • Grus americana - Whooping crane may be particularly susceptible. About 39% of whooping cranes necropsied at the National Wildlife Health Centre were found to be infected. (B36.8.w8)
  • In general, bacterial diseases are seen in cranes which are predisposed to infection due to population or environmental stressors. (B336.20.w20)
LAGOMORPHS Transmission:

In Brachylagus idahoensis - Pygmy rabbit 

  • Thought to be from soil in pens. (J2.37.w3)

In Oryctolagus cuniculus domesticus - Domestic rabbit

  • Associated with close contact with poultry. (J42.26.w1, J212.1.w1)

Susceptibility

In Brachylagus idahoensis - Pygmy rabbit 

  • The susceptibility of pygmy rabbits may have been associated with partially ineffective cell-mediated immunity which was detected in these rabbits. (J2.37.w3)
  • Susceptibility was higher in captive Columbia Basin pygmy rabbits than in Idaho pygmy rabbits of the same age range. (J2.37.w3)

In Oryctolagus cuniculus domesticus - Domestic rabbit

  • Rabbits are known to be susceptible for infection, having been used for many years in studies for example to distinguish between different mycobacteria. However, they appear to be relatively refractory to diseases caused by spontaneous infection, with very few cases reported. (J42.26.w1, J212.1.w1)
FERRETS
  • Ferrets appear to be highly susceptible to Mycobacterium avium infection (and to Mycobacterium bovis and Mycobacterium tuberculosis). (B627.14.w14)
  • Possibly occurs in farmed ferrets (New Zealand) following food contamination by infected wild birds. (J195.11.w2)
  • Experimentally, ferrets were found to be much less susceptible to an isolate of Mycobacterium avium (from a lesion in a farmed deer in New Zealand) than to infection with Mycobacterium bovis). (J42.123.w1)

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Disease has been reported in either the wild or in captivity in:

  • A wide variety of waterfowl, also many other bird species.
  • Captive Canada geese Branta canadensis and Ross's geese Anser rossii, also mute swans Cygnus olor and tundra swans Cygnus columbianus, green-winged (common) teal Anas crecca, wild northern shoveler Anas clypeata, wood duck Aix sponsa (B15).
  • Domestic geese and ducks in Europe (J18.39.w1).
  • Wild mallard Anas platyrhynchos, redhead Aythya americana and gadwall Anas strepera in USA (J5.33.w1).
  • White-headed tree duck (white-faced whistling-duck) Dendrocygna viduata and garganey Anas querquedula (J5.20.w4).
  • Hooded merganser Lophodytes cucullatus in Japan (J5.40.w2).
  • Northern pintail Anas acuta, cinnamon teal Anas cyanoptera in a collection in the UK (J3.140.w3).
  • Wild green-winged (common) teal Anas crecca, redhead Aythya americana, northern pintail Anas acuta, mallard Anas platyrhynchos, northern shoveler Anas clypeata, whistling (tundra) swan Cygnus columbianus (J4.99.w1).
  • Red-breasted merganser Mergus serrator in a collection in the UK (J7.5.w1).
  • African yellow billed duck Anas undulata, New Zealand scaup Aythya novaeseelandiae in a collection in the UK (J7.6.w1).
  • Wild Eurasian wigeon Anas penelope and common shelduck Tadorna tadorna in the UK (J7.9.w1).
  • Wild common pochard Aythya ferina in the UK (J7.11.w2).
  • Wild common eiders Somateria mollisima in the UK (J7.12.w2).
  • Dark-bellied brent goose Branta bernicla on the Wash, UK (J7.25.w1).
  • Seaducks, particularly sawbills (Mergus spp.) in a collection in the UK (J7.30.w2).
  • Shelducks and sheldgeese in a collection in the UK (J7.30.w4).
  • Brazilian teal Amazonetta brasiliensis, maned goose (duck) Chenonetta jubata, mandarin Aix galericulata , Carolina (wood duck) Aix sponsa, pygmy goose Nettapus spp., comb duck Sarkidornis melanotos, Hartlaub's duck Pteronetta hartlaubii, white-winged wood duck Cairina scutulata, muscovy duck Cairina moschata, spur-winged goose Plectropterus gambensis, ringed teal Callonetta leucophrys in a collection in the UK (J7.32.w1).
  • Spotted whistling duck Dendrocygna guttata, Eyton's whistling-duck Dendrocygna eytoni, wandering whistling-duck Dendrocygna arcuata, fulvous whistling-duck Dendrocygna bicolor, Cuban whistling-duck Dendrocygna arborea, Javan (lesser) whistling-duck Dendrocygna javanica, white-faced whistling-duck Dendrocygna viduata, red-billed whistling-duck Dendrocygna autumnalis in a collection in the UK (J7.33.w2).
  • North American ruddy duck Oxyura jamaicensis, white-headed duck Oxyura leucocephala, maccoa duck Oxyura maccoa, blackheaded duck Heteronetta atricapilla, white-backed duck Thalassornis leuconotus in a collection in the UK (J7.33.w3).
  • Adult true or northern geese (Branta spp. and Anser spp.): swan goose Anser cygnoides, bean goose Anser fabalis, pink-footed goose Anser brachyrhynchus, greater white-fronted goose Anser albifrons, lesser white-fronted goose Anser erythropus, greylag goose Anser anser, bar-headed goose Anser indicus, emperor goose Anser canagicus, snow goose Anser caerulescens, Ross's goose Anser rossii, Canada goose Branta canadensis, barnacle goose Branta leucopis, brent goose Branta bernicla, red-breasted goose Branta ruficollis; noted particularly in lesser whitefronted geese Anser erythropus, Canada geese Branta canadensis, and rarely in emperor geese Branta canagicus and greylag geese Anser anser, also reported in juvenile barnacle goose Branta leucopsis and red-breasted goose Branta ruficollis (J7.34.w1).
  • All swan species in a collection in the UK: Bewick's swan Cygnus columbianus bewicki, black swan Cygnus atratus, black-necked swan Cygnus melanocorypha, Coscoroba swan Coscoroba coscoroba, mute swan Cygnus olor, trumpeter swan Cygnus buccinator, whistling swan Cygnus columbianus columbianus, whooper swan Cygnus cygnus (J7.43.w1).
  • Wild mute swan Cygnus olor and Bewick's swan Cygnus columbianus in the UK (J7.43.w2)
  • White-winged wood ducks Cairina scutulata at a collection in the UK (J7.43.w3).
  • Wild waterfowl in British Columbia, Canada (J14.19.w1).
  • Wild mute swan Cygnus olor in the UK (J36.41.w1)
  • Wild mute swan Cygnus olor in the UK (J36.44.w1).
  • Free-living mute swan Cygnus olor, Bewick's swan Cygnus columbianus, ping-footed goose Anser brachyrhynchus, greylag goose Anser anser, Canada goose Branta canadensis, brent goose Branta bernicla, northern pintail Anas acuta, common teal Anas crecca, mallard Anas platyrhynchos, gadwall Anas strepera, Eurasian wigeon Anas penelope, Common pochard Aythya ferina, tufted duck Aythya fuligula in the UK, mainly associated with sites with captive waterfowl (P16.1993.w1).
  • Mute swan Cygnus olor, whistling and Bewicks' (tundra) swans Cygnus columbianus, trumpeter swans Cygnus buccinator, whooper swan Cygnus cygnus, barnacle goose Branta leucopsis (Th2).
  • Common eider Somateria mollissima, Australian grey teal Querquedula gibberifrons (Grey teal Anas gracilis), Eurasian wigeon Anas penelope, common shelduck Tadorna tadorna, tufted duck Aythya fuligula, American wigeon Anas americana, trumpeter swan Cygnus buccinator, (American) green-winged teal Anas crecca, red-headed duck Aythya americana, mallard Anas platyrhynchos, (northern) shoveler Anas clypeata, whistling swan Cygnus columbianus columbianus (B48.10.w10).

Cranes:

Hedgehogs:

Lagomorphs:

In Brachylagus idahoensis - Pygmy rabbit 

  • Disseminated mycobacteriosis diagnosed in 28 captive pygmy rabbits; this was the most common cause of death (28% of the adult captive population) compared with 18 deaths of adults from other causes, June 2002 - September 2004. (J2.37.w3)
  • Spontaneous disease due to Mycobacterium avium has been diagnosed rarely in Oryctolagus cuniculus domesticus - Domestic rabbit. (J212.1.w1)
  • On one farm, 20 adult rabbits and about 40 kits died over a short period. Infection was confirmed in the single rabbit necropsied. (J212.1.w1)

In Oryctolagus cuniculus domesticus - Domestic rabbit

  • Spontaneous infection reported for the first time in two rabbits in 1913. (J42.26.w1)
  • Spontaneous infection reported occasionally, for example confirmed in the one rabbit examined post mortem after 20 adults and 40 kits died on one farm, J212.1.w1)
  • Seen causing respiratory signs associated with a large mass in the nasal passages of a pet rabbit. (P3.2006b.w4)

Ferrets

  • In a pet ferret. (J4.204.w2)
  • In a ferret in a zoo in France (pulmonary infection). (B627.14.w14)
  • In research ferrets obtained from dealers. (B627.14.w14)
  • In a six-year-old neutered male ferret with concurrent lymphoma in the USA. (J212.18.w1)
  • A study of 21,481 feral ferrets from wildlife areas of New Zealand, 2004-2008 detected 175 isolates of Mycobacterium avium complex. (J238.132.w2)

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

WATERFOWL

CRANES

MAMMALS

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Disease has been specifically reported in Free-ranging populations of:

  • A wide variety of species of waterfowl, also many other bird species.
  • Wild green-winged (common) teal Anas crecca, redhead Aythya americana, northern pintail Anas acuta, mallard Anas platyrhynchos, northern shoveler Anas clypeata, whistling (tundra) swan Cygnus columbianus (J4.99.w1).
  • Wild mallard Anas platyrhynchos, redhead Aythya americana and gadwall Anas strepera in USA (J5.33.w1).
  • Wild Eurasian wigeon Anas penelope and common shelduck Tadorna tadorna in the UK (J7.9.w1).
  • Wild common pochard Aythya ferina in the UK (J7.11.w2).
  • Dark-bellied brent goose Branta bernicla on the Wash, UK (J7.25.w1).
  • Wild mute swan Cygnus olor and Bewick's swan Cygnus columbianus in the UK (J7.43.w2)
  • Wild waterfowl in British Columbia, Canada (J14.19.w1).
  • Wild mute swan Cygnus olor in the UK (J36.41.w1)
  • Wild mute swan Cygnus olor in the UK (J36.44.w1).
  • Free-living mute swan Cygnus olor, Bewick's swan Cygnus columbianus, pink-footed goose Anser brachyrhynchos, greylag goose Anser anser, Canada goose Branta canadensis, brent goose Branta bernicla, northern pintail Anas acuta, common teal Anas crecca, mallard Anas platyrhynchos, gadwall Anas strepera, Eurasian wigeon Anas penelope, Common pochard Aythya ferina, tufted duck Aythya fuligula in the UK, mainly associated with sites with captive waterfowl (P16.1993.w1).
  • Common eider Somateria mollissima, Eurasian wigeon Anas penelope, common shelduck Tadorna tadorna, tufted duck Aythya fuligula, American wigeon Anas americana, trumpeter swan Cygnus buccinator, (American) green-winged teal Anas crecca, red-headed duck Aythya americana, mallard Anas platyrhynchos, (northern) shoveler Anas clypeata, whistling swan Cygnus columbianus columbianus (B48.10.w10).

Cranes:

Hedgehogs:

Ferrets

  • A study of 21,481 feral ferrets from wildlife areas of New Zealand, 2004-2008 detected 175 isolates of Mycobacterium avium complex. (J238.132.w2)

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

WATERFOWL

CRANES

MAMMALS

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Environment/Geography

General Information on Environmental Factors/Events and Seasonality

  • The Mycobacterium avium-intracellulare complex associated with Avian Tuberculosis of birds contains organisms of the air-freshwater interface, which are found most commonly in temperate regions, and survive best out of sunlight. Shady conditions and completely enclosed houses, by protecting the bacteria from sunlight, may enhance survival and thereby increase contamination (J7.32.w1, J44.72.w1, P3.1990-1991.w1).
  • Bacteria of the Mycobacterium avium-intracellulare complex associated with Avian Tuberculosis of birds can survive for at least four years and possibly up to seven years in the environment. Sites on which waterfowl have been maintained for many years may have high levels of contamination, due to excretion of bacilli by infected birds over time (B32.7.w43, B14, P3.1990-1991.w1, P16.1993.w1).
  • For wild waterfowl, exposure to the bacterium in wastewater and sewage contaminated sites may be higher in autumn and winter, when they may be attracted since warm water discharges keep water ice-free and hunting is often not allowed at such sites (B36.7.w7).
  • Deaths may occur more frequently in females in summer and in males in winter. This is probably related to differences in energy expenditure, body condition and physiological changes: females reach a low body condition in summer, associated with egg laying and incubation, while males tend to reach their lowest body weight in winter. (J7.32.w1, J7.43.w3, J44.72.w1, P3.1990-1991.w1).
  • Species from very hot and very cold environments may appear more susceptible when maintained in temperate areas due to increased stress from inappropriate climate. Additionally, they may have a lower natural immunity to bacteria of the Mycobacterium avium-intracellulare complex associated with avian tuberculosis of birds, due to less exposure to the organism in their natural environment (J44.72.w1, P3.1990-1991.w1).

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Regions / Countries where the Infectious Agent or Disease has been recorded

  • Worldwide, but most commonly reported from the North Temperate Zone. Variation in occurrence e.g. across Canada and Australia (Th2, B32.7.w3).
  • In the USA (in a ferret with concurrent lymphoma). (J212.18.w1)
  • In the past, laboratory ferrets in Europe (including UK), also from farms in New Zealand. (B627.14.w14)
  • In a ferret in a zoo in France (pulmonary infection). (B627.14.w14)

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Regions / Countries where the Infectious Agent or Disease has been recorded in Free-ranging populations

Worldwide, but most commonly reported from the North Temperate Zone (Th2, B32.7.w3).

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General Investigation / Diagnosis

General Information on Investigation / Diagnosis

WATERFOWL At post mortem examination:
  • Typical pathological lesions (caseous nodules). Numerous acid-fast bacilli seen on Ziehl-Neelsen stained smears of lesions allows presumptive diagnosis.
  • Acid-fast organisms are present within the large phagocytic cells in the form resembling amyloidosis.
  • N.B. Culture and/or identification (standard techniques or molecular techniques) is required for definitive diagnosis of the organism as bacteria of the Mycobacterium avium-intracellulare complex.

(J8.17.w1, B10.26.w10, B11.39.w7, B14, B15, B32.7.w3, B36.8.w8, B37.x.w1)

In live birds:

  • Diagnosis is difficult.
  • The tuberculin test and agglutination tests are useful for diagnosis of infected chicken flocks but less useful for exotic birds. The tuberculin test appears unreliable in ducks and the skin sensitivity response may be 'switched off' in waterfowl with advanced tuberculosis. An agglutination test, which can be carried out on whole blood or serum, was found to be quick and easy to perform, but some false negatives (particularly with blood samples collected into EDTA) and false positives were noted (J6.22.w3, B32.7.w3).
  • An ELISA has been developed which is sensitive, specific and capable of detecting the disease at an early stage, but this is not currently commercially available (J6.22.w3, P4.1993.w4).
  • Haematological changes - anaemia, leucocytosis (high white blood cell count), monocytosis, heterophilia and hyperfibrogenaemia - are seen relatively late in the course of the disease, but may be useful for the detection of individual cases. Early cases may show moderate elevations in white cell counts and heterophilia (J6.19.w1, J6.22.w3).
  • Faeces can be tested for acid-fast bacilli with Ziehl-Neelsen stain or by culture, but the absence of organisms does not confirm a negative diagnosis. Positive findings may indicate the disease but are not in themselves diagnostic.
  • A new technique involving sample processing with a zwitterionic detergent followed by PCR analysis showed high sensitivity but appeared to have a relatively low specificity. This may be a useful screening test for use on faecal samples to identify birds on which further tests should be performed (J2.30.w1).
  • N.B. Bacteria of the Mycobacterium avium-intracellulare complex associated with avian tuberculosis may be isolated from birds without evident clinical disease or lesions i.e. having infection without disease (J6.22.w3).
  • Laparoscopy may be used in particularly valuable individual birds to see liver surface lesions.

(B11.39.w7, B14, B15, B37.x.w1).

CRANES
  • Diagnosis can be difficult. (B115.8.w4)
  • There is no reliable ante-mortem test. (P62.12.w1)
    • The tuberculin skin test for poultry does not work for cranes. (B115.8.w4)
    • In a Grus americana - Whooping crane, tuberculin skin test sites (0.1 mL avian )T and 0.1 mL avian PPD) developed marked induration by 48 hours post injection, with skin fold caliper thickness increased from 2 mm to 5 mm. Biopsy at 72 hours revealed superficial and deeper dermal infiltration by macrophages and lymphocytes, compatible with a delayed type hypersensitivity reaction. (P98.1998.w1)
  • Combination of laparoscopy, liver biopsy and faecal culture. (B115.8.w4)
  • Gross lesions are suggestive but not pathognomonic. A raised white cell count with elevated monocyte percentage is also suggestive. (P62.12.w1)
  • Presumptive diagnosis from the presence of acid-fast bacilli in impression smears. (P62.12.w1)
  • Definitive diagnosis by histopathological examination of biopsy or necropsy samples using acid-fast stains, and by culture and isolation of acid-fast bacilli from affected organs/granulomas. (J1.13.w12, P36.1994.w8, P62.12.w1, P98.1998.w1)
  • Experimental infection of chickens has been used to further confirm infection. (J1.13.w12)
  • In a free-living Grus americana - Whooping crane from the experimental Rocky Mountain flock, histological examination of a biopsy of the cloacal mass revealed numerous coalescing granulomas, surrounding zones of macrophages, and in the centres of many of the granulomas, acid-fast bacilli. Mycobacterium avium complex was then isolated, and confirmed as Mycobacterium avium subsp. avium by specific DNA probe. (P87.7.w9)
LAGOMORPHS In Brachylagus idahoensis - Pygmy rabbit 
  • Physical examination. (J2.37.w3)
  • Radiographs of thorax and skeleton. See: Imaging in Lagomorph Diagnosis and Treatment
    • Note: lesions did not change over the course of the disease (one to three months). (J2.37.w3)
  • Acid-fast stains on prepared cytological samples - aspirates or impression smears - from masses.
  • Haematology and serum biochemistry. 
  • Antibody assays on serum or plasma: immunoblot. (J2.37.w3)
  • Note: mycobacteria were detected by faecal culture in only one individual, although 11 had intestinal granulomas. (J2.37.w3)
  • Sometimes positive by mycobacterial culture of urine or blood. In three animals, culture-positive urine or blood samples developed two to 10 weeks after onset of antibiotic treatment (in previously culture-negative individuals). (J2.37.w3)
  • See: Clinical Pathology of Lagomorphs

In Oryctolagus cuniculus domesticus - Domestic rabbit

  • Necropsy findings of multiple small granulomas, acid fast bacilli detected, and the organism grown in culture. Identity as Mycobacterium avium serovar 2 confirmed following animal inoculations. (J212.1.w1)
  • In a pet rabbit with chronic respiratory signs:
    • Endoscopic examination of the nasal passages, followed by CT scan to determine the extent of the mass seen endoscopically. (P3.2006b.w4)
    • Histopathology (of debrided tissue): granulomatous inflammatory mass in the nasal passages, containing acid-fast organisms. (P3.2006b.w4)
    • Repeated culture of Mycobacterium avium complex. (P3.2006b.w4)
FERRETS
  • Consider Mycobacterium avium (and other mycobacteria) as possible causes of illness in ferrets showing lethargy, weight loss and diarrhoea. (J215.23.w1)
  • Ziehl-Neelsen staining: detection of acid fast bacilli. (J4.204.w2, J212.18.w1)
  • Culture of Mycobacterium avium from spleen and liver following necropsy. (J4.204.w2)
  • PCR: positive for Mycobacterium avium; negative for Mycobacterium bovis and for Mycobacterium avium subsp. paratuberculosis. (J212.18.w1)
Related Techniques
WaterfowlINDEXDisInvTrCntr.gif (2325 bytes)

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Similar Diseases (Differential Diagnosis)

BIRDS
  • Other causes of chronic weight loss and muscle wasting: mycotic diseases, chronic parasitism, nutritional problems. (P1.1975.w3)
WATERFOWL
  • Aspergillosis (Aspergillosis) (caseous nodules), neoplasia (Neoplasias) (B15), yersiniosis (Yersiniosis) (B14).
  • Amyloidosis (Amyloidosis) (for the form of avian tuberculosis characterised by ascites, diffuse liver enlargement (pale and firm), sometimes enlarged spleen (pale and firm) (B15).
CRANES
LAGOMORPHS In Brachylagus idahoensis - Pygmy rabbit 
  • (J2.37.w3)
FERRETS Other mycobacterial infections:

Other causes of weight loss, anorexia and diarrhoea. (J215.23.w1)

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Treatment and Control

Specific Medical Treatment

WATERFOWL
  • Bacteria of the Mycobacterium avium-intracellulare complex associated with Avian Tuberculosis of birds are highly resistant to antituberculous drugs.
  • The simultaneous use of multiple drugs in combination e.g. 1) isoniazid 30mg/kg, ethambutol 30 mg/kg, rifampicin 45 mg/kg (B32.7.w3); 2) rifabutin (56 mg/kg daily), azithromycin (43 mg/kg daily) or clarithromycin (85 mg/kg daily), ciprofloxacin or enrofloxacin (15 mg/kg twice daily, and amikacin (15 mg/kg twice daily), over a period of several months has been used in psittacines and may be effective. Problems with toxicity may be of concern (J29.6.w1).
  • Treatment is not normally attempted as infected birds are a source of infection for others, but might be considered for a particularly valuable individual.

(B10.26.w10, B11.39.w7, B13.46.w1, B15, B32.7.w3, B37.x.w1)

CRANES
  • Antibiotic treatment may reduce clinical signs but not cure the infection. Treatment is not recommended unless the crane is a particularly valuable individual and it can be kept isolated from other animals for the complete treatment period. (P62.12.w1)
  • In a Grus americana - Whooping crane, apparently successful treatment involved several months of administration of ethambutol (Myambutol, Lederle, 30 mg/kg daily) plus rifampin (Rifadin, Marion Merrell Dow, Inc., 30 mg/kg twice daily, later increased to 45 mg/kg once daily); isoniazid was given also on two occasions, but both times caused anorexia within three days, and was discontinued. (P62.12.w1, P87.7.w9, P98.1998.w1)
    • Drugs were loaded into gelatin capsules and given to the bird inside a herring or mouse. (P98.1998.w1)
    • Additionally, after about two months, an experimental immunotherapeutic agent, Mycobacterium vaccae vaccine, was given, 0.05 ml intradermally into the thick skin of the head, repeated after eight weeks. (P87.7.w9, P98.1998.w1)
    • Masses were considerably reduced in size (cloacal mass from 2 cm to 1 cm, abdominal mass and spleen size reduced on radiography) by four months after the start of treatment with antitubercular drugs. By nine months, no masses were palpable and cloacal samples were negative for Mycobacterium avium complex. The crane's weight decreased by 0.34 kg (5% of body mass) over several months of treatment. (P98.1998.w1)
    • About ten months after treatment ceased, weight loss, raised WBC count and radiographic findings led to suspicion of recrudescence of infection. Treatment with azithromycin (Pfizer Laboratories Inc.) at 20 mg/kg once daily in food, then increased to 40 mg/kg after one week, produced dramatic improvement over 16 weeks, with weight gain and a drop in WBC count. However, ethambutol (30 mg/kg daily) was added on the advice of the drug manufacturer to reduce the risk of development of drug resistance and three weeks later the crane was found collapsed and, despite discontinuing the drugs and giving supportive care for three weeks, it deteriorated and was euthanased. At necropsy, no Mycobacterium avium was isolated. (B197.9.w9, P87.7.w9)
      • At necropsy, no Mycobacterium avium or other mycobacteria could be isolated from faeces or tissues, and no acid-fast bacilli were found in any tissues. Severe chronic active fibrosing cardiomyopathy and severe hepatopathy were present, suggestive of a toxic reaction. (P87.7.w9)
LAGOMORPHS In Brachylagus idahoensis - Pygmy rabbit 
  • Azithromycin 50 mg/kg orally every 24 hours, plus rifabutin 25 mg/kg orally every 12 hours. (J2.37.w3)
    • Ethambutol may be added (45 mg/kg orally every 12 hours) to form a triple combination therapy; this triple combination did not produce any adverse effects in more than six months of treatment of one pygmy rabbit. (J2.37.w3)
  • NSAID and/or vitamin E may be given to relieve tissue inflammation/discomfort. (J2.37.w3)
  • Gamma-interferon might be a useful adjunct therapy to try. (J2.37.w3)
  • Granulocyte-macrophage colony-stimulating factor might be synergistic with azithromycin (as shown in mice). (J2.37.w3)

In Oryctolagus cuniculus domesticus - Domestic rabbit

  • In a pet rabbit with a mass in the nasal passages, aggressive debridement followed by rifampin 75 mg/kg orally every 12 hours, azithromycin 50 ,g/kg orally every 24 hours and ciprofloxacin 10 mg/kg orally every 12 hours appeared effective for about eight months. Later (due to change of sensitivity as indicated by a sensitivity panel), clarithromycin 50 mg/kg orally every 24 hours, rifabutin 25 mg/kg orally every 12 hours and ethambutol 45 mg/kg orally every 12 hours. (P3.2006b.w4)
FERRETS --
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General Nursing and Surgical Techniques

WATERFOWL --
CRANES
  • In a Grus americana - Whooping crane, initial treatment included intravenous fluids, steroids, antibiotics, reduction of the cloacal prolapse (including a 2 cm mass) and insertion of a purse-string suture, and tube-feeding for a week until it became self-feeding. (P87.7.w9, P98.1998.w1)
LAGOMORPHS --
FERRETS
  • In a pet ferret with a jejunal constriction, surgical excision of the affected area and end-to-end anastomosis (mycobacterial infection was not diagnosed at that time). (J4.204.w2)
    • Eight months later, a further 1 cm diameter raised mass was resected from the pylorus. (J4.204.w2)
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Preventative Measures

Vaccination WATERFOWL
  • No commercial vaccines are available.
  • A vaccine has been being developed and is presently being trialled at The Wildfowl and Wetlands Trust.

(Th2, J7.40.w3, B11.39.w7, V.w4).

Prophylactic Treatment

WATERFOWL

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Environmental and Population Control Measures

General Environment Changes, Cleaning and Disinfection

BIRDS

Good hygiene and sanitation. (P1.1975.w3) 
WATERFOWL
  • Good hygiene, removal and incineration of build-ups of droppings and organic matter
  • Turning of soil and removal of shading vegetation will increase bacterial decay due to sunlight.
  • Removal of topsoil, liming and replacement of clean soil could be used to decontaminate an area, but even this may not be effective.
  • The use of wastewater to maintain or create wetlands for wild waterfowl should be carefully thought out with the risks of introducing mycobacteria into the environment assessed. The use of wastewater for either captive or free-living waterfowl should be avoided unless testing and/or treatment can assure the water is free of Mycobacterium bacilli.

(B11.39.w7, B36.8.w8, B37.x.w1, P4.1992.w1)

CRANES
  • Infected individuals intermittently shed organisms, contaminating the soil. Strict sanitation is required. (P62.12.w1)
LAGOMORPHS For Brachylagus idahoensis - Pygmy rabbit 
  • House in non-soil pens, if possible, or sterilise the soil before putting it in the pens. (J2.37.w3)

 

FERRETS
  • Food should be protected from wild birds which might contaminate food with Mycobacterium avium. (B627.14.w14)
Population Control Measures BIRDS
  • If a large proportion of birds in a collection are probably infected, euthanasia of the whole population followed by restocking at a new site might be required to eliminated the infection. (P1.1975.w3)
WATERFOWL
  • Keep stocking densities low.
  • Ensure birds are well fed and avoid stress.
  • Avoid contact between wild and captive birds.

(B11.39.w7, B37.x.w1)

  • Particularly sensitive species should be maintained in a separate pen with a clean water supply and extra care to reduce stress by e.g. minimising disturbance, keeping stocking densities low and social groups appropriate, with access to heated winter accommodation if appropriate (J7.43.w3).

CRANES
  • For wild flocks, providing more habitat and thereby dispersing concentrated flocks may prevent spread of the disease. (P62.12.w1)
LAGOMORPHS --
FERRETS --
Isolation, Quarantine and Screening BIRDS
  • Ideally, keep a bird collection isolated from wild birds; this is not generally practical. (P1.1975.w3)
WATERFOWL
  • Birds entering a collection should be quarantined, preferably for 60 days, and screened for tuberculosis.
  • Foster-hens for rearing ducklings should be tuberculin tested.
  • Birds know to be infected should be euthanased. Individuals of high conservation value could be maintained in isolation.
  • Destruction of flocks know to be infected has been used in poultry.

(J8.17.w1, B10.26.w10, B11.39.w7, B13.46.w1, B15, B32.7.w3, B36.8.w8, B37.x.w1, P4.1992.w1)

CRANES
  • Strict quarantine is important. (P62.12.w1)
LAGOMORPHS For Brachylagus idahoensis - Pygmy rabbit 
  • Prevent access of carrier birds to enclosures holding pygmy rabbits(J2.37.w3)

 

FERRETS --
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