Chlamydial infections in animals
Chlamydophila psittaci in birds: Clinical
signs
A common sign of chlamydial infection in many birds is conjunctivitis or keratoconjunctivitis
(Meyer, 1965). In parrots, parakeets and other cage birds, acute disease is characterised by diarrhoea, anorexia and droopiness
(Storz, 1988). In racing pigeons, respiratory signs such as
rhinitis ,
bronchitis and
inflammation of the air sac predominate. In C. psittaci infections of ducks, serous or
pussy nasal and ocular discharges are typical, resulting in encrusted eyes and nostrils
(Grimes and Clark, 1986).
In general, early signs of disease in avian species may include respiratory signs such as
dyspnoea,
rales,
coryza and sinusitis, unilateral conjunctivitis, diarrhoea and
polyuria. In the acute phase of infection, further signs may be apparent, such as
reduced body temperature, lethargy,
loss of appetite, weight loss, dehydration, ruffled plumage, and the voiding of greenish-yellow gelatinous droppings. Egg production is reduced. In a flock infected with highly virulent
strains of C. psittaci, there may be 50-80% morbidity and 10-30% mortality.
In the sub-acute or chronic phase of infection there may be central nervous system disturbances
(Harrison, 1989), such as flaccid paresis and hind limb paralysis as in cockatiels;
or conjunctivitis, which may be recurrent and not completely resolved by antibiotic treatment.
Pathological changes include damage to the respiratory system, heart, kidneys, spleen, brain, reproductive organs and liver
(Page, 1978).
The lungs are usually congested with a pussy, serous or fibrinous pleural
exudate. The air sac membranes may also be thickened and cloudy. Enlargement of the spleen is commonly observed in
psittacine birds and pigeons. Livers are usually swollen, haemorrhagic and discoloured. The intestinal tract may be
congested and inflamed in cases with diarrhoea (Grimes and
Wyrick, 1991).
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infections
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