Feline
Chlamydiosis
Feline
chlamydiosis (also known as feline pneumonitis) is a relatively
mild, chronic upper respiratory disease caused by
the bacterium Chlamydia psittaci. The main symptom is conjunctivitis,
an abnormal eye discharge due to inflammation of the conjunctiva,
the membrane lining the inside of the eyelid. The infection can
also cause nasal discharge, sneezing, and pneumonia. Left untreated,
the infection tends to become chronic, lasting weeks or months.
Chlamydiosis is part of the feline upper respiratory infection
(URI) complex, a group of viral and bacterial infections (e.g.,
feline rhinotracheitis, feline calicivirus) that affects the nose
and eyes and manifests similar symptoms. Chlamydiosis accounts for
about 10% to 15% of all feline URI cases and often occurs with another
URI.
Incidence
and Prevalence
Chlamydiosis occurs worldwide and affects about 5% to 10% of the
cat population. It is especially common in kittens (2 to
6 months old), in multicat households, and in pet adoption
shelters. Outbreaks tend to occur in overcrowded, poorly ventilated,
and unsanitary settings; and where cats are poorly fed or stressed,
either physically (e.g., extreme temperatures) or psychologically
(introduction of a new cat).
Causes
Feline
pneumonitis is caused by Chlamydia psittaci, an intracellular bacteria
(i.e., bacteria that lives inside a cell), which also affects birds
and humans. Chlamydia psittaci reproduces in the cells that line
the respiratory tract, causing irritation and the mild symptoms
that characterize chlamydiosis. It can also reproduce in the gastrointestinal
and reproductive tracts but usually doesn’t cause symptoms
in either place.
Transmission
The bacteria that causes chlamydiosis can spread from upper respiratory
tract secretions. Common methods of transmission include the
following:
..... Contact
with contaminated objects, such as cages, food and water bowls,
litter pans, pet owner’s clothing, and pet owner’s hands
.....Contact with an infected cat’s mouth, nose, or eye discharge
.....Sneezing and coughing that propels the virus as far as 4 feet
Carrier cats that don’t show symptoms but harbor the bacteria
in their conjunctiva can shed the virus in their eye discharge.
The likelihood that bacteria will be present in the discharge is
greater after stressful events. (e.g., introduction of a new cat
into the household).
Though uncommon, there have been reported cases of mild human conjunctivitis
caused by feline Chlamydia psittaci.
Symptoms
Chlamydiosis
is symptomatic only in the respiratory tract and eyes. The infection
may not cause any symptoms, unless another URI is present. When
symptoms do appear, the most common include the following:
Anorexia
(may occur as the disease progresses)
Coughing
Difficulty breathing
Fever (may occur as the disease progresses)
Pneumonia (in young kittens 2 to 4 weeks old, which could
be fatal)
Runny nose (rhinitis)
Sneezing
Watery eyes due to conjunctivitis (either one or both eyes)
Conjunctivitis is inflammation of the conjunctiva, the thin, transparent
membrane that lines the inside of the eyelid. The inflammation leads
to discharge, swelling, and pain; the cat’s eyes may be red
and weepy. This is the main symptom of chlamydiosis and usually
occurs initially in one eye and eventually affects both eyes. Rarely,
it become chronic.
Although C. psittaci colonizes the reproductive tract, it doesn’t
cause symptoms. It’s not clear whether it affects pregnancy
or not. Sometimes kittens that are born to infected mothers develop
severe conjunctivitis at, or shortly after, birth.
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