Chlamydiosis / Psittacosis (with special reference to Waterfowl and notes on Bears, Lagomorphs and Ferrets)

Disease Summary

• Strain M56 of Chlamydia psittaci is reported to cause epizootic chlamydiosis in Lepus americanus - Snowshoe hares resulting in high mortality. Other lagomorphs are resistant to infection with this strain. (B282.30.w30,B614.8.w8)
• There have also been other reports of "Chlamydia sp." being isolated from rabbits with conjunctivitis and pneumonia; however the significance of these reports is unclear. (B614.8.w8)

• Chlamydia infects ferrets through their intranasal passages and can cause pneumonia and pneumonitis. (B232.6.w6)

Alternative Names (Synonyms)

• Ornithosis
• Epizootic chlmydiosis (in snowshoe hares and muskrats) (J1.12.w)

Disease Type

Infectious/Non-Infectious Agent associated with the Disease

• Recently reclassified as Chlamydophila psittaci. (B336.73.w73, J238.75.w1)
• Serovar D is the most virulent in turkeys; serovars B and E have also been associated with outbreaks of disease in turkeys. (J4.221.w11)

In lagomorphs:

• Strain M56 (four isolates, two from the blood and spleen of Lepus arcticus - Arctic hare and two from Ondatra zebethicus spatulatus - Muskrat involved in a die-off in Saskatchewan, Canada); strain M56 was from a muskrat, but the four strains were considered to be identical to one another. (J240.30.w1)
• M56 strain is the only known Chlamydia psittaci strain that is pathogenic for lagomorphs, causing epizootic chlamydiosis in Lepus americanus - Snowshoe hares. (B282.30.w30, B614.8.w8, J1.12.w15)

Infective "Taxa"

• Chlamydia psittaci

Non-infective agents

Physical agents

References

Disease Author

Major References / Reviews

Code and Title List

Other References

Code and Title List

Bears
J1.29.w15

Lagomorphs
B282.30.w30, B614.8.w8
J1.12.w15, J13.32.w3

Ferrets
B232.6.w6, B627.14.w14

Detailed Clinical and Pathological Characteristics

May cause asymptomatic infection through to severe disease. (B336.73.w73

Subclinical or latent infection:

• Asymptomatic (no clinical signs). (B36.10.w10, B48.13.w13)
  • This form of infections is common. (J69.16.w2)

Acute or subacute infection:

• Sudden death may occur with acute infection, or disease may be severe and rapidly fatal. (B36.10.w10, D48)The disease may progress over days or weeks. (D48)
• Acute disease: depression, inactivity, inappetance, diarrhoea with yellow-green gelatinous droppings and raised body temperature (2-3 °C above normal) (B48.13.w13)
  • Acute or subacute disease: serous or purulent ocular or nasal discharge, anorexia, inactivity, then diarrhoea (may be grey or rusty with blood). Develops to total inactivity with a fixed posture and sometimes respiratory distress. (B48.13.w13)
  • In the subacute form progression is slower, signs less pronounced and time to death in fatal infections is prolonged. The disease may subside and reappear at weekly intervals, causing weight loss, growth retardation and in time emaciation. (B48.13.w13)
• Weakness, anorexia, purulent oculonasal discharge, become motionless, with a fixed body posture, huddling with ruffled feathers. Diarrhoea may be rust coloured due to blood, or dark green in birds which have stopped eating. Respiratory distress may develop. Rapid weight loss. Death may occur in one to two days. (B36.10.w10)
• Dullness (feather fluffing, inactive), respiratory signs, mucopurulent nasal discharge, diarrhoea and polyuria; droppings may be yellow (bile pigments). (J238.45.w1)
  • General signs: commonly depression, anorexia, weight loss, ruffled feathers (as with other systemic illnesses). (B12.23.w11, B336.73.w73, D48, N7.49.w3)
  • Digestive and urinary tract signs are common, with diarrhoea and green or yellow-green watery urine (biliverdinuria) (B12.23.w11, B336.73.w73, D48)
    • The urinary component of droppings may be green (biliverdinuria) due to effects on liver function with systemic infection. (B336.73.w73, N7.49.w3)
    • Droppings of anorectic birds may be sparse and dark green. (N7.49.w3)
  • With respiratory tract infection (common) there may be keratoconjunctivitis, rhinitis, sinusitis, dyspnoea and râles. (B12.23.w11, B336.73.w73)
  • Later emaciation, dehydration and death. (N7.49.w3)
  • CNS signs (uncommon) include convulsions, tremors, head tilt, posterior paresis. (B12.23.w11, B336.73.w73, J238.45.w1)
  • Infertility and deaths of nestling birds may be seen, with or without clinical signs being seen in adult birds. (B336.73.w73)
• Note: other infections may occur concurrently; these can affect the clinical signs. (B12.23.w11)
• Signs may vary depending on the species:
  • In budgerigar and cockatiel collections: reduced production of eggs, decreased hatchability and mortality of nestlings may be noted. (B12.23.w11)
    • Conjunctivitis (unilateral or bilateral), keratoconjunctivitis; intermittently bile-stained droppings. In budgerigars also often sinusitis. (J238.45.w1)
  • In lovebirds both juvenile and adult mortality may be high. (B12.23.w11)
  • In Australian parakeets, sporadic mortality and conjunctivitis may be noted, without other clinical signs. (B12.23.w11)
  • In Amazon parrots, green-stained urine (indicating hepatic dysfunction) may be the main sign. (B12.23.w11)
    • Occasionally CNS signs occur. (J238.45.w1)
  • In macaws, lower respiratory signs, including severe dyspnoea, may predominate. (B12.23.w11)
    • Occasionally CNS signs occur. (J238.45.w1)
  • In cockatoos: chronic wasting and other general signs, or asymptomatic. (B12.23.w11)
  • In pigeons: Mucopurulent ocular discharge is often the first sign and strongly suggestive of this disease. (B36.10.w10)
    • Respiratory signs are common, decreased flying performance may be seen. (J238.45.w1)
    • Clinical disease may be seen only in conjunction with another infection. (J238.45.w1)
    • In chronically infected individuals, lameness, torticollis, opisthotonus, tremor and convulsions may occur. (J238.45.w1)
  • In pheasants and chickens: generally systemic illness is seen only in young birds. (B12.23.w11)
  • In ratites: high chick mortality and nonspecific general signs in adults. (B12.23.w11)
  • In turkeys: depression, ruffled feathers, anorexia, cachexia, mild diarrhoea with yellow droppings, and respiratory signs (oculonasal discharge, cough, dyspnoea). (J238.45.w1)
  • In chickens: (usually only in young chicks) blindness, weight loss. (J238.45.w1)

(D48, B36.10.w10, B101)

Clinical pathology:

• No changes in asymptomatic birds. (B336.73.w73)
• Haematology: Anaemia; leucocytosis with heterophilia and sometimes monocytosis. (B12.23.w11, B336.73.w73)
• Clinical biochemistry: Raised plasma aspartate aminotransferase (AST), lactate dehydrogenase (LDH), plasma bile acids, beta globulins and sometimes uric acid. (B12.23.w11, B336.73.w73)

Radiography, laparotomy:

• Air sac thickening, hepatomegaly and splenomegaly may be evident. (B12.23.w11, B336.73.w73)

• Conjunctivitis is common. (B12.23.w11)
• Trembling, gait imbalance and muscular atrophy, cachexia, variable anorexia, greenish and watery diarrhoea. Conjunctivitis, infraorbital sinusitis, sometimes panophthalmitis and bulbar atrophy, rhinitis: serous to purulent oculo-nasal discharge with surrounding feathers crusted, dyspnoea. (In geese also torticollis and wing-droop). Emaciation, terminal convulsions. Severe reduction in egg laying in domestic ducks.
• Retarded plumage development and growth of survivors, also leg weakness
• N.B. Conjunctivitis and rhinitis, or keratoconjunctivitis may be main or only sign. Cornea may become involved leading to blindness.
• N.B. Form with minimal or absent clinical signs also recorded.

(J3.110.w3, J4.195.w2, B11.34.w2, B11.37.w5, B13.46.w1, B13.34.w5, B14, B15, B16.19.w1, B32.15.w22, B48.13.w13).

In Lepus arcticus - Arctic hare (Species)

• Natural infection:
  • Illness and death. (B282.30.w30)
• Experimental infection with strain M56 in Lepus arcticus - Arctic hare: (B282.30.w30, J240.34.w1)
  • Fever. (J240.34.w1)
    • Typically biphasic febrile response with a rise in body temperature of 0.5 - 1.0 °C on the second or third day after infection and a further rise of 2.3 °C on the fifth day; terminally, body temperature fell. (J240.34.w1)
    • Hares may become passive, but remain alert. (B282.30.w30)
  • Weight loss (loss of about 8% of body weight), emaciation. (J240.34.w1)
    • Hares did continue eating, but with reduced food consumption. (J240.34.w1)
  • Diarrhoea in some hares. (B282.30.w30)
  • Icterus in some hares. (B282.30.w30)
  • Just before death, lethargy, inappetance and falling body temperature. (B282.30.w30)
  • Terminally, opisthotonus, convulsions and hypoglycaemia. (J240.34.w1)
  • Death usually after 5-13 days; two hares died after just 60 hours. (J240.34.w1)
• Experimental infection with strain M56: (J1.12.w15)
  • Fever, weight loss, death after 5-14 days. (J1.12.w15)
• Experimental infection with strains virulent in birds: (J1.12.w15)
  • Fever, but no mortality. (J1.12.w15)

Rabbits with Chlamydia sp. Infection

There have been several reports of the isolation of Chlamydia sp. from rabbits; however the significance of these reports is unclear. (B614.8.w8):

• Conjunctivitis
  • Spontaneous conjunctivitis was reported in six rabbits and attributed to Chlamydia. The diagnosis was reached by indirect fluorescent antibody tests performed on conjunctival smears and remission of clinical signs was seen after tetracycline treatment. [1985] (B614.8.w8)
• Pneumonia
  • A chlamydial agent was isolated from the lungs of a domestic rabbit (Oryctolagus cuniculus domesticus) that had pneumonia. A mild and self-limiting pneumonia was then reproduced experimentally by the injection of this agent intratracheally. [1971] (B614.8.w8, J13.32.w3)
  • Another case of pneumonia was reported in 1989. (B614.8.w8)

Experimental inoculation of strain M56 of Chlamydia psittaci

• Experimental infection of Oryctolagus cuniculus domesticus - Domestic rabbit and Sylvilagus floridanus - Eastern Cottontail rabbit with strain M56: (J1.12.w15)
  • Fever.
  • Weight loss.
  • No deaths.

  (J1.12.w15)

• Experimental intravenous inoculation of albino Oryctolagus cuniculus domesticus - Domestic rabbit: (J240.38.w1)
  • Fever (1.1 - 2.2 °C rise in temperature) by six days after intravenous inoculation, returning to normal by15 days. (J240.38.w1)
  • Lethargy and emaciation. (J240.38.w1)
  • Anterior uveitis, with hyperaemia at 2-3 days post-inoculation, and by 5-6 days "deep dull red vascular injection near the corneoscleral limbus." Iris congested and oedematous, pupil small and poorly reactive to light. Congestion of both anterior uvea and conjunctiva clearing by day 10. 
  • In one individual, unilateral opacity of the cornea on days 7-9. 

  (J240.38.w1)

  Anterior uveitis: 

  • Oryctolagus cuniculus - European rabbit and Sylvilagus floridanus - Eastern Cottontail rabbit usually survive experimental infection with few lesions. However, anterior uveitis has been reported to occur in Oryctolagus cuniculus - European rabbit after intravenous inoculation of Chlamydia psittaci. (B614.8.w8)

• Pneumonitis and pneumonia can occur in ferrets, if there is intranasal infection. (B232.6.w6, B627.14.w14)
• Diarrhoea. (B627.14.w14)

Incubation

• Three days to several weeks following exposure. (B36.10.w10, N7.49.w3)
• Five to ten days in experimental infections with virulent strains. (J69.16.w2)
• Five to 98 days in psittacines, as little as two to four days in turkeys. (B48.13.w13)
• Infection may be carried for years. (B36.10.w10, D48).

• Experimental infection of strain M56 in Lepus arcticus - Arctic hare: (J240.34.w1)
  • Fever usually by 2-3 days and deaths in 2-13 days. (J240.34.w1)

Mortality / Morbidity

• Most infections in wild birds are inapparent. (J4.195.w2)
• There are few reports of morbidity and mortality associated with this disease in wild birds, however such incidents may be underdiagnosed. (J4.195.w2)
• Mortality may be high; birds rarely recover from clinically apparent disease (D48).
• Can cause sporadic and local mortality incidents but the true prevalence in wild birds is unknown. (D48)
• Variable depending on the strain of the organism (B101).
• Morbidity and mortality may be increased in wild birds brought into captivity. (J4.195.w2)
• In domestic turkeys, morbidity rates of 0-80% and mortality rates up to 30% are seen. (J4.195.w2)
  • With serovar D, 50-50% morbidity and 5-30% mortality. (J4.221.w11)
• In domestic chickens, egg production may drop and mortality may reach up to 30%. (J4.195.w2)
• Morbidity and mortality may be highest in young, naive birds (B48.13.w13).

• Epizootics have occurred in domestic ducks. 
• Morbidity and mortality may be moderate to high in ducklings. (B12.23.w11)
• Morbidity 10 to 80%, Mortality up to 30% in ducks, up to 100% in ducklings, up to 55% in goslings.
• Infection in domestic ducks is generally linked to serovar C. (J4.221.w11)

• Mortality is high in Lepus americanus - Snowshoe hare with epizootics of strain M56 Chlamydia psittaci infection; other lagomorphs are resistant to infection with this strain. (B614.8.w8)
• Experimental infection of strain M56 in Lepus arcticus - Arctic hare was fatal in 15/16 individuals. (J240.34.w1)
• Experimental infection of Lepus arcticus - Arctic hare with strain M56 was lethal in (J1.12.w15)
• Experimental infection of Lepus arcticus - Arctic hare with strains virulent in birds resulted in fever but did not cause mortality. (J1.12.w15)

Pathology

• As with clinical signs, the severity of pathological lesions varies depending on the strain or the organism, the host's susceptibility, the route of exposure and concurrent disease. (J238.45.w1)

Gross pathology:

• Ocular: Conjunctivitis (B12.23.w11, D48), keratitis. (B12.23.w11)
• Respiratory - Nasal discharge (D48), air sacculitis (B336.73.w73) air sacs may be thickened, showing diffuse cloudiness and fibrinous deposits. (B12.23.w11); may be lung congestion (B36.10.w10, J238.45.w1), pneumonia (D48, B12.23.w11, J69.16.w2)
• Gastro-intestinal - Faecal staining of feathers around vent (D48), enteritis.(B12.23.w11, B336.73.w73, D48); congestion may be seen, particularly on the serosal surface. (J238.45.w1)
• Liver - enlarged (hepatomegaly) (D48, B12.23.w11, B48.13.w13, B336.73.w73, J69.16.w2, J238.45.w1) - may be 3-4 times normal size. (B36.10.w10) may be mottled and congested. (B12.23.w11); may be friable, green or yellowish and with small necrotic foci on the surface or the cut surface. (J238.45.w1)
• Spleen - enlarged (splenomegaly) (D48, B12.23.w11, B48.13.w13, B336.73.w73, J69.16.w2, J238.45.w1) - may be 3-4 times normal size (B36.10.w10) May be mottled and congested. (B12.23.w11); may have a softer consistency than normal; there may be petechiae on the surface, or necrotic foci (white). (J238.45.w1)
  • Intense vascular congestion, subcapsular haemorrhage and splenic rupture occurs occasionally. (B48.13.w13)
• Body cavity - fibrinous peritonitis, pericarditis (B12.23.w11, B36.10.w10, B48.13.w13, B336.73.w73), air sacculitis (B12.23.w11, B36.10.w10, B48.13.w13, D48); serositis with yellowish exudate (J69.16.w2); air sacs thickened and cloudy, may be covered with thick, yellowish fibropurulent exudate. (J238.45.w1) Pericarditis may be purulent, serous or fibrinous. (J238.45.w1)
• Renal: nephrosis. (B12.23.w11, B336.73.w73)
• Cardiac: Necrotic areas are occasionally visible. (J238.45.w1)
• Note: 
  • Necrotising lesions are seen with acute disease while proliferative changes occur if disease follows a longer time course. (B48.13.w13)
  • Classical lesions such as hepatomegaly are not always present. (B12.23.w11)
  • Some birds show no lesions, but are shedding the organism. (J69.16.w2)

(B12.23.w11, B36.10.w10, B101, B336.73.w73, D48)

Histopathology:

• Changes may be minimal in acute fatal cases. (J238.45.w1)
• Non-specific changes. (B12.23.w11)
• Affected organs: inflammation, necrosis. (B336.73.w73)
• Liver: focal necrosis with monocyte proliferation, epithelioid granulomas. (B12.23.w11); dilatation of sinusoids may be seen, with mononuclear cell, lymphocyte and heterophil infiltration. (J69.16.w2) 
  • Proliferation of lymphoid tissue around the bile ducts, leading to bile duct compression necrosis of the duct wall, infiltration of bile into the liver parenchyma, and hepatic necrosis. (B48.13.w13)
  • Focal necrosis with heterophil, macrophage and plasma cell infiltration has been described in parakeets. (J69.16.w2)
  • Periportal infiltration with heterophils and mononuclear cells is common. (J238.45.w1)
  • In acute infection multifocal coagulative necrosis may be noted. (J238.45.w1)
  • In more chronic infection, bile duct hyperplasia and reticular-endothelial cell proliferation. (J238.45.w1)
  • Haemosiderosis may be seen. (J238.45.w1)
  • In chronic infection there may be significant hepatic fibrosis and mononuclear cell infiltrates. (J238.45.w1)
• Spleen, kidney focal necrosis with monocyte proliferation (B12.23.w11)
• Spleen: reticular-endothelial cell hyperplasia with lymphoid hyperplasia and plasmocytosis may be seen; necrosis also may be present. (J238.45.w1)
• Renal: acute necrosis, mixed inflammatory infiltrate. (J238.45.w1)
• Trachea: tracheitis with the lamina propria and submucosa showing extensive infiltration with mononuclear cells, lymphocytes and heterophils. (J69.16.w2)
• Lung: bronchopneumonia, epithelioid granulomas. (B12.23.w11) Focal infiltration of mononuclear cells, oedema, congestion and haemorrhage. (J69.16.w2) mild pneumositis. (J238.45.w1)
• Body cavities: fibrinous air sacculitis, pericarditis, peritonitis. (B12.23.w11); mononuclear cell and heterophil infiltration of the air sacs; there may also be proliferation of the epithelium and connective tissue. (J238.45.w1)
• GIT: plasmacytic lymphocytic enteritis. (J238.45.w1)
• Cardiac: Myocarditis which may be diffuse; occasionally large necrotic areas. (J238.45.w1)
• CNS: (in individuals showing nervous signs) nonsuppurative meningitis may be present. (B12.23.w11); lesions are rarely seen in the brain. (J238.45.w1)
• Bone marrow: increase in the granulocytic cell series. (J238.45.w1)
• Adrenals: inflammatory lesions may be present. (J238.45.w1)
• Gonads: inflammatory lesions may be present. (J238.45.w1)

• Ocular lesions: conjunctivitis, abundant serous to purulent exudate.
• Liver - hepatomegaly and focal necrosis, stained yellow.
• Serosal surfaces - perihepatitis, peritonitis, pericarditis, air sacculitis.
• Lungs - pulmonary oedema and hyperaemia.
• Spleen - splenomegaly and focal necrosis, sometimes necrotic tumour-like nodules.
• Muscular - muscle atrophy
• Reproductive - salpingitis and oophoritis

N.B. often secondary bacterial infection.

Histopathology:
Exudation and necrosis (acute), histocytic and reticuloendothelial cell infiltration (chronic).

(B10.26.w10, B11.37.w5, B13.34.w5, B14, B15, B16.19.w1, B36.10.w10, B48.13.w13)

• Lungs: 
  • Interstitial pneumonia with proliferation of lymphoid tissue around airways and vessels. (B614.8.w8)
  • Eosinophilic inclusions and elementary bodies may be seen with special stains. (B614.8.w8)
  • A mild exudation of heterophils was seen in a case of mild pneumonia that was produced experimentally by intratracheal injection of a chlamydial agent. A pronounced accumulation of macrophages in the alveolar septae and the alveoli were also seen. (B614.8.w8)

Chlamydia psittaci strain M56 infection

• Natural infection in Lepus arcticus - Arctic hare: (B282.30.w30, J240.30.w1)
  • Hepatic: congestion, some with whitish-yellow necrotic foci on the liver surface.
  • Spleen: enlargement (slight to very marked).
  • GIT: stomach empty. Often severe enteritis. 

  (B282.30.w30, J240.30.w1)

• Experimental infection in Lepus arcticus - Arctic hare: (B282.30.w30, J240.34.w1)
  • Hepatic: marked hepatomegaly. Liver friable, tan to brown in colour, with scattered white to yellow foci throughout the liver.
  • Spleen: marked splenomegaly (at least three times normal size), black and friable. On the cut surface, the pulp bulged.

  (B282.30.w30, J240.34.w1)

Histopathology

• Liver and spleen: Chlamydia psittaci proliferates within the monocyte-macrophage system resulting in congestion and focal necrosis of the spleen and liver. (B614.8.w8)
• Experimental infection of Lepus arcticus - Arctic hare:
  • Hepatic: marked necrosis with hepatic cells in various degrees of degeneration. (B282.30.w30, J240.34.w1)
  • Spleen: Red and white pulp augmented, particularly white pulp after several days of infection. Often haemosiderin in splenic macrophages. (B282.30.w3, J240.34.w1)
  • CNS: cerebral meningeal blood vessels congested. (J240.34.w1)
  • Virus is present at high titre in blood and many organs, being highest in spleen, liver and bone marrow, which appear to be the main sites for virus replication. (J1.12.w15)
• Experimental intravenous inoculation of albino Oryctolagus cuniculus domesticus - Domestic rabbit: (J240.38.w1)
  • Ocular: iritis, with accumulation of plasma cells (predominating), lymphocytes and monocytes in both the iris and the ciliary bodies. Occasionally elementary bodeis in macrophages. In one individual, posterior synchia. In another rabbit, unilateral corneal thickening with oedema, proliferation of fibroblasts and linfiltration of the substantia propria with leucocytes. (J240.38.w1)
  • Chlamydial agent was recovered from conjunctival swabs and from intraocular tissues. (J240.38.w1)

• Respiratory:
  • Lung lobes firm, plum-coloured and oedematous. (B232.6.w6, B627.14.w14)
  • Bronchiolar exudate maybe present in the lumen. (B232.6.w6, B627.14.w14)
  • Oedematous alveolar walls. (B627.14.w14)

Histopathology

• Respiratory:
  • Bronchiolar epithelia may be hyperplastic. (B232.6.w6, B627.14.w14)
  • Alveolar walls oedematous, with a dense infiltrate of large mononuclear cells. (B232.6.w6, B627.14.w14)
  • Alveolar spaces are distended; mononuclear cells predominate in the cellular exudate, although polymorphonuclear cells are also present. (B232.6.w6, B627.14.w14)

Human Health Considerations

• Important, sometimes fatal, zoonosis.
• This disease is transmitted by inhalation of airborne particles of droppings and other discharges (oral, ocular) from birds. (B12.22.w13, B23.22.w5, B363.2.w2, This disease, which causes flu-like illness in humans, is transmitted by inhalation of airborne particles of droppings and other discharges (oral, ocular) from birds. (B12.22.w13, B23.22.w5, B363.2.w2))
• Severe 'flu-like illness with high fever, headache, debility and shortness of breath. May be fatal if not treated (D48).
• While 'flu-like illness is seem most commonly, atypical pneumonia, and occasionally cardiac and neurological effects may be seen. (B23.22.w5)
  • The incubation period is about one to two weeks (B23.22.w5); four to 15 days or longer (P24.327.w4); five to 14 days. (B12.22.w13)
  • Chills, fever, headache, aches and pains (myalgia), coughing and general malaise may occur. (B12.22.w13, P24.327.w4, P24.334.w4)
    • Upper or lower respiratory tract signs may be seen. (P24.334.w4)
    • Respiratory signs may be mild despite extensive changes visible radiographically. (P24.334.w4)
    • Less commonly, anorexia, diaphoresis, nausea, photophobia, thoracic pain and vomiting may be present. (B12.22.w13)
  • If treatment is delayed, symptoms may become severe. (B23.22.w5); pneumonia (often develops (B12.22.w13) and heart disease may occur. (P24.327.w4)
  • About 87% of affected humans require hospitalisation; less than 1% fatality is seen if treatment is correct (B12.22.w13)
  • Tetracycline, doxycycline or erythromycin are usually used for treatment. (B23.22.w5)
    • Doxycycline is the drug of choice. (P24.334.w4)
  • Diagnosis is based on paired serum samples showing a rise in antibody titre. (P24.334.w4)
  • Recovery is usually rapid and complete but immunity is short lived, therefore reinfection can occur. (B23.22.w5)
    • The normal course of disease in humans is about seven to 10 days. (P24.327.w4)
  • Note: Clinical signs are similar to those of the human (nonzoonotic) chlamydiosis caused by Chlamydia pneumoniae. Some serological tests fail to distinguish between infections with these two organisms. (B23.22.w5)
• Parrot keepers, pigeon fanciers and other pet bird owners are recognised as being at risk of contracting this disease. (B12.22.w13, D48)
• Individuals who are immunocompromised are at greater risk of contracting this disease. (P24.334.w4)
• Workers in duck processing plants are particularly at risk and infections have also been reported in wildlife biologists working with snow geese Anser (Chen) caerulescens (Anser caerulescens - Snow goose), sandhill cranes Grus canadensis, common egrets, snowy egrets, white-winged doves, and ducks.
• Veterinarians, zoo workers etc. are recognised to be 'at risk' of contracting chlamydiosis. It may be advisable to wear a mask or respirator if working in an area where airborne avian faecal material is likely to be inhaled, and to dampen areas of dry, dusty avian droppings with disinfectant or 5% bleach.
• (J4.195.w1, J4.195.w2, J4.203.w1, B15, B12.22.w13, B32.15.w22, B36.10.w10, B101, D48)
• Chlamydiosis is a notifiable disease in most of the USA. (B12.22.w13, J4.195.w1)

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

• Particularly in colonial-nesting species, captive psittacines, and other cage birds; also sporadically in poultry. (B101)
• Collared doves (Streptopelia decaocto - Eurasian collared-dove) and robins (Erithacus rubecula - European robin) in Britain (D48).
• Ducks, geese and swans (B32.15.w22).
• Ducks in the UK (J3.112.w1).
• Domestic ducks and geese in central Europe (B36.10.w10).
• Domestic ducks Anas platyrhynchos domesticus in the UK, causing conjunctivitis and rhinitis (J3.110.w3).
• Commercial domestic ducklings in the UK, in combination with duck viral hepatitis (J3.116.w2).
• Mallards in Czechoslovakia (J4.195.w2).
• Infection detected by isolation and/or antibody detection in: Greylag goose Anser anser, white-fronted goose Anser albifrons, lesser white-fronted goose Anser erythropus, mallard, Anas platyrhynchos, gadwall Anas strepera, pintail Anas acuta, common (green-winged) teal Anas crecca, gargany Anas querquedula, European wigeon Anas (Mareca) penelope, (northern) shoveler Anas (Spatula) clypeata, European (common) pochard Nyroca ferina, common goldeneye Bucephala clangula, tufted duck Aythya fuligula, greater scaup Aythya marila, common scoter Melanitta (Oidemia) nigra, smew Mergellus albellus, in Bulgaria and former USSR (B48.13.w13).

In mammals

• Antibodies to Chlamydia psittaci were detected by complement fixation (CF) test in sera from 1/22 Ursus arctos - Brown bear from Croatia (the positive individual was captive, not free-living). [1993](J1.29.w15)
• Infection occurred in Mustela putorius furo - Ferrets inoculated with human tracheal washings for iinfluenza research. (B627.14.w14)

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

• Anas acuta - Northern pintail
• Anas clypeata - Northern shoveler
• Anas crecca - Common teal
• Anas penelope - Eurasian wigeon
• Anas platyrhynchos - Mallard
• Anas platyrhynchos domesticus - Domestic duck
• Anas querquedula - Garganey
• Anas strepera - Gadwall
• Anser albifrons - Greater white-fronted goose
• Anser anser - Grey-lag goose
• Anser erythropus - Lesser white-fronted goose
• Aythya fuligula - Tufted duck
• Aythya marila - Greater scaup
• Bucephala clangula - Common goldeneye
• Melanitta nigra - Black scoter
• Mergellus albellus - Smew

MAMMALS

• Mustela putorius furo - Ferret
• Ursus arctos - Brown bear

Lagomorphs:

• Lepus americanus - Snowshoe hares
• Oryctolagus cuniculus domesticus - Domestic European rabbit

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

In waterfowl: 

• Infection recorded in waterfowl in the USA, and in the Caspian Sea (B36.10.w10).
• Mallards in Czechoslovakia (J4.195.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

• Anas platyrhynchos - Mallard

Lagomorphs:

• Lepus americanus - Snowshoe hares

General Information on Environmental Factors/Events and Seasonality

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

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

General Information on Investigation / Diagnosis

• Consider in the differential diagnosis list for any sick bird. (B336.73.w73)
• Diagnosis cannot be made solely on gross pathological lesions. (B36.10.w10, J69.16.w2)
• Clinical signs, gross and histological lesions, serology, isolation of the agent. (B48.13.w13)
• Purulent ocular discharge with severe illness is suggestive in young pigeons (B36.10.w10)
• Gross lesions, particularly splenomegaly and hepatomegaly may be suggestive but are not pathognomonic. (B36.10.w10)
• Whole birds should be submitted for diagnosis if possible, otherwise lung, spleen, liver and affected air sacs (B36.10.w10)
• Histopathology (D48)
• Cytology: examination of smears or tissue impressions (using special stains or by immunofluorescence). (B12.23.w11, D48)
  • Giminez and Machiavello's stain should be used to identify intracytoplasmic chlamydial inclusions.(B12.23.w11)
  • Direct smears from faeces, cloacal swabs or nasal or ocular exudates may be examined but are unlikely to show positive unless large numbers of the organisms are shed. (B12.23.w11)
  • Impression smears from the liver, spleen or air sac are more likely to give positive results, particularly with immunofluorescent stains. (B12.23.w11)
• Detection of antigens by ELISA (D48)
• Isolation of Chlamydia sp. (B36.10.w10)
  • N.B. detection of the organism, in the absence of typical pathological findings, does not prove the cause of death, as this organism may be carried by healthy birds. (D48)
• Diagnosis can be confirmed by a combination of serology plus PCR or culture of the organism. (B336.73.w73)
• In the USA as described by CDC [N7.49.w3 - Text copied directly]:

• Serology: Detection of antibodies to the agent indicates that the bird has been exposed, but not necessarily the presence of an active infection. (N7.49.w3)
  • False negatives may occur early in infection, prior to seroconversion. The antibody response may be reduced with antimicrobial treatment. (N7.49.w3)
  • In a single bird, serological results are most likely to be useful when considered in conjunction with signs of disease and flock history, and together with white blood cell count and liver enzyme activity levels.
  • A single high titre suggests active infection. (B12.23.w11
  • Greater than fourfold titre increase in paired samples, or a positive titre together with detection of antigen is required for confirming diagnosis. (N7.49.w3)
    • Note: the ideal interval between collection of paired sera has not been established for most bird species. (B12.23.w11
  • Direct complement fixation test: This is more sensitive than agglutination methods; the modified direct CF test is more sensitive than the direct CF test. False negative reactions can occur, for example in specimens from small psittacines. Note that high titres can persist following treatment (B12.23.w11) which may make interpretation of subsequent tests problematic. (N7.49.w3)
  • Elementary-body agglutination: This commercially available test can detect early infection. Again, elevated titres may persist after the end of treatment. (N7.49.w3)
    • This test detects IgM and is therefore very useful for detecting active infection. (B336.73.w73)
  • Indirect immunofluorescence: detects IgG; this may remain elevated for long periods after resolution of the disease. (B336.73.w73)
  • Latex agglutination: titres > 640, or rising titres, indicate active infection; asymptomatic carrier birds may show false-negative results. A long time after treatment may be required for titres to decline. (B12.23.w11)
• Antigen detection:
  • ELISA Test kits originally designed for detection of Chlamydia trachomatis in humans do not require viable organisms to give a positive result (unlike culture), and give rapid results. Their sensitivity for detection of C. psittaci in birds is not known and false-positives from cross-reacting antigens can occur (e.g. with Staphylococcus aureus, Staphylococcus hyicus, Actinobacillus salpingitis, Acintobacter calcoaceticus) (B12.23.w11). False-negatives can occur if there is insufficient antigen present. Results must be interpreted alongside clinical findings. A negative result cannot exclude the diagnosis of chlamydiosis. A positive result in a clinically healthy bird should be verified by isolation of the organism. (N7.49.w3) Sensitivity is less than the sensitivity of culture. (B12.23.w11)
  • Immunofluorescent antibody tests (IFA) use monoclonal or polyclonal antibodies, fluorescein staining and fluorescent microscopy to detect the organism in specimens such as impression smears. Advantages and disadvantages are similar to those of ELISA. (N7.49.w3)
  • Polymerase Chain Reaction (PCR) detects the target DNA in specimens such as choanal or cloacal swabs, or blood. The test should be sensitive and specific but requires validation. (N7.49.w3)
    • A single swab used to sample both the choana and cloaca is preferred for use with this test in a live bird. (B336.73.w73)
• Isolation of the agent: This is the best means for confirming the diagnosis (B36.10.w10, N7.49.w3). Since Chlamydophila (Chlamydia) psittaci is an obligate intracellular parasite, isolation requires tissue culture, mice or chick embryos. (N7.49.w3)
  • From a live bird: Collect combined choanal and cloacal swab specimens (depending on signs in the bird), refrigerate and send to the laboratory on ice but NOT frozen. Note that a special transport medium is required. (N7.49.w3)
    • Note: Contact the diagnostic laboratory regarding specific procedures for collection and submission of specimens. (N7.49.w3)
    • To reduce costs while maximising the chance of detection (since shedding may not occur constantly), serial samples may be collected for three to five days, then pooled prior to culture. (N7.49.w3)
  • At necropsy: The agent may be isolate from liver, spleen, air sacs, pericardium, heart or intestines. Collection of liver and spleen (N7.49.w3, B36.10.w10, B336.73.w73); air sac (B36.10.w10, B336.73.w73) or lung (B36.10.w10) is preferred for culture.

• Clinical signs, pathological lesions, serology and isolation of Chlamydia psittaci (B48.13.w13).
• Chlamydia organisms within mononuclear cells in fixed tissues or impression smears of tissues (liver, spleen, lung, air sac, exudates), with e.g. Giemsa, Giminez, Macchiavello or modified Ziehl-Neelsen stain. Detection by immunohistochemical staining, ELISA and PCR are not yet reliable (B14, B15, B16.19.w1, B32.15.w22).
• The ELISA may be useful for ascertaining the immune status of duck flocks (J3.115.w
• Presence of LCL bodies in macrophage-like cells are pathognomonic, but these are difficult to detect (B13.34.w5).
• Isolation and identification from tissues (air sac, spleen, pericardium, heart, liver, kidney) collected aseptically or in live birds from conjunctival scraping, cloacal swab, tracheal or nasal swab, whole blood or if necessary faeces. May be stored at 4ºC for a short time, or at -20ºC indefinitely (B10.26.w10, B14, B15, B32.15.w2).
• Serology, particularly complement fixation test, may detect recent exposure (B15, B16.19.w1, B32.15.w22).

• Physical Examination of Birds - General
• Physical Examination of Mammals
• Necropsy of Birds - General
• Necropsy of Mammals
• Treatment and Care - General
• Chapter 2 - B36 Field Manual of Wildlife Diseases - Specimen Collection and Preservation
• Chapter 3 - B36 Field Manual of Wildlife Diseases - Specimen shipment
• Appendix A - B36 Field Manual of Wildlife Diseases - Sample specimen history form

Similar Diseases (Differential Diagnosis)

Specific Medical Treatment

• Macrolide antibiotics (D48)
• Fluoroquinolone antibiotics (D48)
• In poultry flocks, chlortetracycline at 200-400 g per ton of mash feed for at least three weeks (B101)
• In small psittacines and other seed eaters, chlortetracycline at 0.5 mg/g hulled millet seed; for larger psittacines 4-10 mg/g food, for fruit and nectar eaters 0.5 mg/mL nectar. Administer for 35-40 days (B101)
• Doxycycline, 20 mg/kg bodyweight twice daily, for 35-40 days (B101).
• Medicated food containing 1% chlortetracycline, e.g. medicated pellets or extruded pellets, or powder mixed with mash diets. (N7.49.w3)
  • Hulled millet impregnated with chlortetracycline at 0.5 mg per gram of seed can be used for parakeets, budgerigars, finches, canaries. (J238.45.w1)
  • Medicated pellets containing 5000 ppm chlortetracycline can be used for lovebirds and for larger psittacines. (J238.45.w1)
  • Medicated hen feed containing chlortetracycline at 5000 ppm can be used for pigeons. (J238.45.w1)
  • Medicated food should be given for 45 days. (J238.45.w1)
  • Note: Dietary calcium should be reduced to 0.7% to reduce interference with chlortetracycline absorption. (J238.45.w1)
  • Birds may show poor acceptance of the medicated feed; chlortetracycline mash has a bitter taste, and pellets may be infective if the birds do not accept pellets as food items
• Medicated water containing 400 mg doxycycline hyclate per litre of water for cockatiels, 400-600 mg per litre for most other psittacines. Note that toxicity may occur, indicated by depression, inactivity, reduced appetite, green/yellow stained urine and elevated aspartate aminotransferase 9AST), lactate dehydrogenase (LDH) and bile acids. (N7.49.w3)
  • Note: Medicated water is NOT suitable for medication of either psittacines or pigeons as these birds rarely drink sufficient volume to take in enough medication. (J238.45.w1)
• Doxycycline (monohydrate or calcium syrup formulation) orally. Dosages for psittacines are: 40-50 mg/kg once daily for cockatiels, Senegal parrots, blue-fronted Amazons and orange-winged Amazons, 25 mg/kg once daily for African grey parrots, Goffin's cockatoos, blue and gold macaws, green-winged macaws, with suggested starting doses of 25-30 mg/kg once daily for other cockatoos and macaws, and 25-50 mg/kg once daily for other psittacines. Another treatment should be used for individuals which regurgitate the drug. (B12.23.w11, N7.49.w3)
  • This should preferably be given on an empty crop to maximise absorption. (J238.45.w1)
• Doxycycline by intramuscular injection into the pectoral muscles. All formulations will cause irritation at the injection site. Vibrovenos (Pfizer) has been formulated for intramuscular administration and can be administered at 75 to 100 mg/kg every five to seven days for four weeks, then every five days for the rest of the treatment time. (B12.23.w11, J238.45.w1, N7.49.w3)
• Doxycycline in the injectable hyclate formulation for intravenous use in humans can be given intravenously in birds but NOT intramuscularly as it will cause a severe tissue reaction at the injection site. (N7.49.w3)
• Long-acting oxytetracycline, 75 mg/kg subcutaneously every three days for Goffin's cockatoos, blue and gold macaws, blue-fronted Amazons and orange-winged Amazons. This treatment causes irritation at the injection site and is suggested to initiate treatment in birds which are ill or reluctant to eat, with treatment then changed to another less irritant drug. (N7.49.w3)
• Oxytetracycline can also be given at 50 mg/kg bodyweight twice daily, however this can cause tissue necrosis at the injection site, therefore use for more than a week is not recommended. (J238.45.w1)
• Enrofloxacin can be given. It is recommended that the dose used should provide a minimum blood level of enrofloxacin of 0.5 mg/L for at least 14 days. Dose rates of 250 ppm enrofloxacin in food for budgerigars and 500 ppm for other psittacines has been sued successfully; use of medicated corn containing 1,000 ppm enrofloxacin was required for elimination in a group of Senegal parrots in quarantine. (J238.45.w1)

Note:

• Treatment for 45 days is recommended. (B12.23.w11)
• Treatment with antibiotics may not always be successful, because the organism may remain in its dormant form within cells for long periods, and is not susceptible to antibiotics during this time, only while metabolically active or reproducing. (B12.23.w11)

• Tetracyclines (chlortetracycline - 0.044%, 400g/ton, 1,000 ppm, 18.2g/kg of food daily for 45 days, or 100 mg/kg), doxycycline (8-25 mg/kg oral twice daily, or 240 ppm in food daily for 45days, or 75 mg/km intramuscular six times at weekly intervals), enrofloxacin 500 ppm in feed or 10 mg/kg intramuscularly twice daily for 14 days), chloramphenicol and erythromycin are effective, penicillin is less effective (B10.26.w10, B11.37.w5, B13.46.w1, B32.15.w22).
• 750 g oxytetracycline per ton of feed for three weeks. (J238.45.w1)
• Multi-resistant forms have been recorded, e.g. with resistance to tetracycline, erythromycin and tylosin (J3.112.w1).

• Tetracyclines suggested; high doses and a long course of treatment might be needed to clear infection. (B282.30.w30)
• Tetracycline has been reported as a successful treatment for conjunctivitis caused by Chlamydia sp. (B614.8.w8)

• Treatment and Care - General

General Nursing and Surgical Techniques

• Minimise stress, including avoiding exposure to adverse climatic conditions. (B12.23.w11)
• Weigh before treatment to establish a baseline and monitor carefully during treatment. (B12.23.w11)
• Tube feeding and general supportive care are required for birds which are ill or losing weight. (B12.23.w11)
• Intravenous fluid therapy may be needed. (J238.45.w1)
• Provide a heated environment. (J238.45.w1)
• Supplementation of the diet with lactulose and vitamins has been suggested. (J238.45.w1)
• Note: Great care should be taken with regard to the potential dangers of transmission of the disease to persons nursing or caring for the birds and with the transmission of the disease to other birds in a hospital or similar environment. (B12.23.w11, V.w6)

• Treatment and Care - General

Preventative Measures

• Vaccines produced to date have not provided immunity; this may be related to differences in strains or serovars. (J238.45.w1)

WATERFOWL

• Preventative Medicine for Birds - General

Environmental and Population Control Measures

• General hygiene (B12.23.w11, B32.15.w22).
• Collection and euthanasia of sick birds, to reduce transmission from sick birds (B36.10.w10).
• Removal and incineration of carcasses, to reduce infective material in the environment (B36.10.w10).
  • Care should be taken not to disturb living birds since these may move and spread the disease to other areas. (B36.10.w10)
• Improve hygiene at bird feeders and take steps to minimise densities at such feeders. (D48)
• Wet down dry dusty areas contaminated with bird droppings using 5% household bleach, or a commercial disinfectant. (B36.10.w10)
• Note: the organism is unstable when exposed to light or heat, but stable for months within dried droppings. (B12.23.w11)
• The organism is susceptible to disinfectants including quaternary ammonium products, benzalkonim chloride, 70% ethanol, 3% hydrogen peroxide. (B12.23.w11)
• Nest boxes should be thoroughly cleaned. (B12.23.w11)

• Isolation of commercial flocks from feral or wild birds (B32.15.w22).
• In a captive / hospital environment consideration should be given to the ability of some species of the parrot family (Psittacines) to carry Chlamydia psittaci asymptomatically and to act as reservoir hosts. (V.w6)

• Preventative Medicine for Birds - General
• Environmental and Population Management - General
• Treatment and Care - Euthanasia
• Chapter 4 - B36 Field Manual of Wildlife Diseases - Disease Control Operations
• Chapter 5 - B36 Field Manual of Wildlife Diseases - Euthanasia