The purpose of this compendium is
to provide information about avian
chlamydiosis and psittacosis to veterinarians,
public health officials, physicians,
members of the pet bird industry,
and others concerned with controlling
these diseases and protecting public
health. The recommendations in this
compendium provide standardized procedures
for controlling avian chlamydiosis
in birds, a vital step to protecting
human health. This version of the
Compendium was modified specifically
for the Journal of the AVMA; copies
of the Compendium are available from
state health departments, or at the
address below. This Compendium can
also be accessed electronically at
the AVMA (www.avma.org) and CDC (www.cdc.gov)
websites.
Chlamydia psittaci is a bacterium
that can be transmitted from pet birds
to humans. In humans, the resulting
infection is referred to as psittacosis
(also known as parrot fever and ornithosis).
Chlamydia psittaci infection often
causes influenza-like symptoms, and
can lead to severe pneumonia and nonrespiratory
health problems. With proper treatment,
the disease is rarely fatal. From
1988 through 1997, the Centers for
Disease Control and Prevention (CDC)
received 766 reports of psittacosis,
which is probably an underestimate
of the actual number of cases because
psittacosis is difficult to diagnose
and is often not reported. During
the 1980s, approximately 70% of cases
of psittacosis in which the source
of infection was known resulted from
human exposure to caged pet birds;
of these, bird fanciers and owners
of pet birds were the largest group
affected (43%). Pet shop employees
accounted for an additional 10% of
cases. Other people at risk include
pigeon fanciers and people whose occupations
place them at risk for exposure (eg,
employees in poultry slaughtering
and processing plants, veterinarians,
veterinary technicians, laboratory
workers, workers in avian quarantine
stations, farmers, wildlife rehabilitators,
and zoo workers). Because infection
can result from transient exposure
to infected birds or their contaminated
droppings, people without identified
avocational or occupational risk may
become infected.
Chlamydia psittaci has been isolated
from approximately 100 species of
birds; it is most commonly isolated
from psittacine birds, especially
cockatiels and parakeets. Among caged,
nonpsittacine birds, infection with
C. psittaci develops most commonly
in pigeons, doves, and mynah birds.
The prevalence of infection in canaries
and finches is believed to be lower
than in psittacine birds. The recommendations
in this Compendium provide standardized
procedures for controlling avian chlamydiosis
(AC) in the pet bird population, an
essential step in efforts to control
psittacosis in humans. This Compendium
is intended to guide veterinarians,
public health officials, physicians,
persons in the pet bird industry,
and others concerned with the control
of C. psittaci and the protection
of public health.
Transmission of Psittacosis Infection
in Humans--Because other species of
Chlamydia can cause diseases in humans,
the disease resulting from the infection
with C. psittaci is commonly referred
to as psittacosis rather than chlamydiosis.
Psittacosis typically results from
exposure to pet psittacine birds.
However, transmission has been documented
from wild birds, including doves,
pigeons, birds of prey, and shore
birds. Infection usually develops
when a person inhales the organism
that has been aerosolized from dried
feces or respiratory secretions of
infected birds. Other means of exposure
include mouth-to-beak contact and
handling of infected birds' plumage
and tissues. Brief exposures can lead
to symptomatic infection; therefore,
patients with psittacosis may not
recall or report having contact with
birds. Certain strains of C. psittaci
infect sheep, goats, and cattle, causing
chronic infection of the reproductive
tract, placental insufficiency, and
abortion. These strains of C. psittaci
are occasionally transmitted to humans
if they are exposed to birth fluids
and placentas of infected animals.
Another strain of C. psittaci, the
feline keratoconjunctivitis agent,
typically causes rhinitis and conjunctivitis
in cats. Transmission of this strain
from cats to humans appears to occur
rarely. Human-to-human transmission
has been suggested but not proven.
Standard infection-control precautions
are sufficient for humans with psittacosis,
and specific isolation procedures
(eg, private room, negative pressure
air flow, and masks) are not indicated.
Clinical signs and symptoms--The onset
of C. psittaci-related illness typically
follows an incubation period of approximately
5 to 14 days, but longer incubation
periods have been reported. The severity
of disease ranges from inapparent
illness to systemic illness with severe
pneumonia. Before antimicrobial agents
were available, 15 to 20% of humans
with psittacosis died. However, <1%
of humans who are properly treated
now die as a result of infection.
Humans with symptomatic infection
typically have abrupt onset of fever,
chills, headache, malaise, and myalgia.
They usually develop a nonproductive
cough that may be accompanied by breathing
difficulty and chest tightness. A
pulse-temperature dissociation (fever
without increased pulse), large spleen,
and rash are sometimes found; such
symptoms are suggestive of psittacosis
in people with community-acquired
pneumonia. Auscultatory findings may
underestimate the extent of pulmonary
involvement. Radiographic findings
include lobar or interstitial infiltrates.
The differential diagnosis list for
psittacosis-related pneumonia includes
infection with Coxiella burnetii,
Mycoplasma pneumoniae, Chlamydia pneumoniae,
Legionella sp, and respiratory viruses
such as influenza. Chlamydia psittaci
can affect organ systems other than
the respiratory tract, and infection
can result in endocarditis, myocarditis,
hepatitis, arthritis, keratoconjunctivitis,
and encephalitis. Respiratory failure,
thrombocytopenia, hepatitis, and fetal
death has been reported in pregnant
women with psittacosis.
Case definition--The Council of State
and Territorial Epidemiologists and
the CDC have established case definitions
for epidemiologic purposes but not
for use as sole criteria for establishing
clinical diagnoses. A patient is considered
to have a confirmed case of psittacosis
if clinical illness is compatible
with psittacosis and the case is laboratory
confirmed by one of the following
methods: C. psittaci is cultured from
respiratory secretions; antibody against
C. psittaci is increased fourfold
or greater to a reciprocal titer of
32 between paired (ie, acute- and
convalescent-phase) serum samples
obtained at least 2 weeks apart, as
demonstrated by complement fixation
(CF) or microimmunofluorescence (MIF);
or immunoglobulin M antibody against
C. psittaci is detected by MIF to
a reciprocal titer of 16. A patient
is considered to have a probable case
of psittacosis if clinical illness
is compatible with psittacosis, the
case is epidemiologically linked to
a confirmed case of psittacosis, or
if a single antibody titer of 1:32
(demonstrated by CF or MIF) is found
in at least one serum sample obtained
after onset of symptoms.
Diagnosis--Until recently, the diagnosis
was primarily established by use of
serologic methods in which paired
sera were tested for Chlamydia antibodies
by CF. However, because chlamydial
CF antibody is not species-specific,
high CF titers also may result from
infection with Chlamydia pneumoniae
and Chlamydia trachomatis. Acute-phase
serum samples should be obtained as
soon as possible after onset of symptoms,
and convalescent-phase serum samples
should be obtained 2 weeks after onset.
Because treatment with tetracycline
can delay or diminish the antibody
response, a third serum sample might
help confirm the diagnosis. Sera should
be tested simultaneously at the same
laboratory. If the epidemiologic and
clinical history indicate a possible
diagnosis of psittacosis, MIF and
polymerase chain reaction (PCR) assays
can be used to distinguish infection
with C. psittaci from infection with
other chlamydial species. Information
about laboratory testing often is
available at state laboratories. The
infectious agent also can be isolated
from the patient's sputum, pleural
fluid, or clotted blood during acute
illness and before treatment with
antimicrobial agents; however, culture
of C. psittaci is performed by only
a few laboratories because of technical
difficulty and safety concerns. Few
commercial laboratories have the capability
to differentiate chlamydial species.
Several laboratories will accept specimens
of human origin to confirm psittacosis.
Treatment--Tetracyclines are the
drugs of choice for treating humans
with psittacosis. Most persons respond
to oral administration of 100 mg of
doxycycline twice a day or 500 mg
of tetracycline hydrochloride 4 times
a day. For initial treatment of severely
ill persons, doxycycline hyclate may
be administered IV at a dosage of
4.4 mg/kg (2 mg/lb) of body weight
per day divided into 2 infusions per
day (up to 100 mg per dose). In past
years, tetracycline hydrochloride
has been administered (10 to 15 mg/kg
[4.5 to 6.8 mg/lb] of body weight,
IV, q 24 h, divided into 4 doses per
day), but a preparation for injection
is no longer available in the United
States. Remission of symptoms usually
is evident within 48 to 72 hours.
However, relapse may develop, and
treatment must continue for at least
10 to 14 days after fever abates.
Although its in vivo efficacy has
not been determined, erythromycin
probably is the best alternative agent
for humans for whom tetracycline is
contraindicated (eg, children <
9 years old and pregnant women).
Transmission from Infection in Birds--Shedding
of the infectious agent in birds with
latent chlamydiosis may be activated
by stress factors, including shipping,
crowding, chilling, and breeding.
Birds can appear healthy but be carriers
of C. psittaci and shed the organism
intermittently. The organism is shed
in feces and nasal discharges, is
resistant to drying, and can remain
infectious for several months.
Clinical signs--For caged birds,
the time between exposure to C. psittaci
and onset of illness ranges from 3
days to several weeks. However, latent
infections are common in birds, and
active disease may appear years after
exposure. Birds with chlamydiosis
may have no clinical signs or may
have an acute, subacute, or chronic
clinical disease. Whether the bird
has clinical signs of illness or dies
depends on the species and age of
the bird, virulence of the strain,
infectious dose, stress factors, and
extent of treatment or prophylaxis.
Birds with clinical signs of AC typically
have manifestations (eg, lethargy,
anorexia, and ruffled feathers) consistent
with those of other systemic illnesses.
Other signs associated with AC include
serous or mucopurulent ocular or nasal
discharge, diarrhea, and excretion
of green to yellow-green urates. Anorectic
birds may produce sparse, dark green
droppings. Birds can die soon after
onset of illness, or, as the disease
progresses, they can become emaciated
and dehydrated before death.
Case definition--A confirmed case
of AC is defined on the basis of at
least one of the following laboratory
results: isolation of C. psittaci
from a clinical specimen; identification
of chlamydial antigen in tissues by
immunofluorescence (IFA); a greater
than fourfold change in serologic
titer in 2 samples obtained at least
2 weeks apart and assayed simultaneously
at the same laboratory; or identification
of C. psittaci within macrophages
in smears or sections of tissues stained
with Gimenez or Machiavelo stain.
A probable case of AC is defined as
C. psittaci infection in a bird that
has clinical illness compatible with
AC and either a high serologic titer
in one or more samples obtained after
onset of signs or the presence of
C. psittaci antigen (identified by
enzyme-linked immunosorbent assay
[ELISA], PCR, or IFA) in feces, a
cloacal swab, or respiratory or ocular
exudates. A suspected case of AC is
defined as clinical illness compatible
with AC that is epidemiologically
linked to another case in a human
or bird but not laboratory confirmed;
a nonclinical infection in a bird
with a single high serologic titer
or detection of chlamydial antigen;
illness in a bird that has positive
results for infection on the basis
of a nonstandardized or new investigational
test; or clinical illness compatible
with chlamydiosis that is responsive
to appropriate treatment.
Diagnosis and treatment--Several
diagnostic methods are available for
identifying AC (Appendix 2). Veterinarians
can choose from 3 methods for treating
AC--chlortetracycline-medicated feed,
oral or parenteral treatment with
doxycycline or oxytetracycline, and
experimental treatment with late-generation
macrolides, pharmacist-compounded
injectable doxycycline, and doxycycline-medicated
feed. Although these methods can be
successful, knowledge about treatment
of AC is evolving, and no treatment
protocol guarantees safe treatment
or complete elimination of C. psittaci
in all bird species. Therefore, treatment
should be supervised by a licensed
veterinarian.
Recommendations and Requirements
Controlling infection in humans and
birds--To prevent transmission of
C. psittaci, specific control measures
are recommended for veterinarians
and their staff, physicians, and members
of the pet bird industry. To protect
people at high risk of becoming infected,
those in contact with infected birds
should be informed about the nature
of the disease. People at risk should
be instructed to wear protective clothing,
gloves, a paper surgical cap, and
a respirator with an N95 rating or
a higher-efficiency respirator when
cleaning cages or handling infected
birds. Surgical masks may not be effective
in preventing transmission. When necropsies
are performed on potentially infected
birds, additional precautions should
be taken, including wetting the carcass
with detergent and water to prevent
aerosolization of infectious particles
and working under an examining hood
that has an exhaust fan. Maintain
accurate records of all bird-related
transactions to aid in identifying
sources of infected birds and potentially
exposed persons. Records should include
the date of purchase, species of birds
purchased, source of birds, and any
identified illnesses or deaths among
birds. In addition, when birds are
sold by a store, the seller should
record the name, address, and telephone
number of the customer; the date of
purchase; the species of birds purchased;
and the band numbers if applicable.
Do not purchase or sell birds that
have signs of AC (eg, ocular or nasal
discharge, diarrhea, or low body weight).
Isolate newly acquired birds for 30
to 45 days, and test or prophylactically
treat them before adding them to a
group. Consider birds that have been
to shows, exhibitions, fairs, and
other events as new acquisitions,
and isolate them upon return to the
facility. Test for AC before birds
are boarded or sold on consignment,
and house them in a room separate
from other birds. Practice preventive
husbandry. Position cages to prevent
transfer of fecal matter, feathers,
food, and other materials from one
cage to another. Do not stack cages,
and be sure to use solid-sided cages
or barriers if cages are adjacent.
The bottom of the cage should be made
of wire mesh. Litter (eg, newspapers)
that will not produce dust should
be placed underneath the mesh. Clean
cages and food and water bowls daily.
Soiled bowls should be emptied, cleaned
with soap and water, rinsed, placed
in a disinfectant solution, and rinsed
again before reuse. Between occupancies
by different birds, cages should be
thoroughly scrubbed with soap and
water, disinfected, and rinsed in
clean, running water. Exhaust ventilation
should be sufficient to prevent accumulation
of aerosols. Prevent spread of infection.
If AC is confirmed, probable, or suspected,
birds requiring treatment should be
isolated. Rooms and cages where infected
birds were housed should be cleaned
immediately and disinfected thoroughly
to eliminate chlamydial organisms
from the environment. While its cage
is being cleaned, the bird should
be transferred to a clean cage. Thoroughly
scrub the soiled cage with detergent
to remove fecal debris; rinse the
cage, disinfect it (allowing at least
5 minutes of contact with disinfectant),
and rerinse it to remove disinfectant.
Discard items that cannot be adequately
disinfected (eg, wooden perches, nest
material, and litter). While birds
are being treated, minimize circulation
of feathers and dust by taking precautions
such as wet-mopping the floor frequently
with disinfectants and preventing
air currents and drafts within the
area. Reduce contamination from dust
by spraying the floor with a disinfectant
or water before sweeping it. Do not
use a vacuum cleaner, because vacuuming
can cause aerosolization of infectious
particles. Frequently remove waste
material from the cage (after moistening
the material), and burn or double-bag
the waste for disposal. When possible,
care for healthy birds before handling
isolated birds. Use disinfection measures.
Because C. psittaci has a high lipid
content, it is susceptible to most
disinfectants and detergents. In the
clinic or laboratory, a 1:1,000 dilution
of quaternary ammonium compounds (eg,
Roccal, Zephiran) is effective, as
is 70% isopropyl alcohol, 1% Lysol,
1:100 dilution (ie, 2.5 tbsp/gal of
water [10 ml/L]) of household bleach,
or chlorophenols. Chlamydia psittaci
is susceptible to heat but is resistant
to acid and alkali. Many disinfectants
are respiratory irritants and should
be used in a well-ventilated area.
Avoid mixing disinfectants with any
other product.
Treatment and care of infected birds--Birds
in which AC is confirmed or probable
should be isolated and treated, preferably
under the supervision of a veterinarian.
Birds in which AC is suspected or
those previously exposed to AC should
be isolated, and retested or treated.
Because treated birds can be reinfected
with C. psittaci after treatment,
such birds should not be exposed to
untreated birds or other potential
sources of infection. To prevent reinfection
from environmental sources, aviaries
should be thoroughly cleaned and sanitized.
A vaccine against AC is not available.
General recommendations should be
followed by bird owners and dealers
when treating and caring for birds
in which AC is confirmed, probable,
or suspected. Protect birds from undue
stress (eg, chilling or shipping),
poor husbandry, or malnutrition. These
problems reduce effectiveness of treatment
and promote development of secondary
infections with other bacteria or
yeast. Observe the birds daily, and
weigh them every 3 to 7 days. If the
birds are not maintaining weight,
have them reevaluated by a veterinarian.
Avoid use of high dietary concentrations
of calcium or other divalent cations
because they inhibit absorption of
tetracyclines. Remove oyster shells,
mineral blocks, and cuttlebones. Isolate
birds that are to be treated in clean,
uncrowded cages. Clean up all spilled
food promptly; wash food and water
containers daily. Provide fresh water
and appropriate food daily. Continue
medication for the entire treatment
period to avoid relapses. Birds may
appear clinically improved and have
reduced shedding after 1 week.
Responsibilities of physicians and
veterinarians--People exposed to birds
with AC should seek medical attention
if they develop influenza-like symptoms
or other respiratory illness. The
physician should collect specimens
for laboratory analysis and initiate
early and specific treatment for psittacosis.
Most states require physicians to
report cases of psittacosis to the
appropriate health authorities. Timely
diagnosis and reporting may help identify
the source of infection and control
the spread of disease. Because determination
of one serum titer is insensitive
and nonspecific for diagnosis of psittacosis,
high titers should be confirmed by
evaluating paired acute- and convalescent-phase
sera. Birds that are suspected sources
of human infection should be referred
to veterinarians for evaluation and
treatment. Local and state authorities
may conduct epidemiologic investigations
and institute additional disease-control
measures (see Local and State Epidemiologic
Investigations). Veterinarians should
be aware that AC is not a rare disease
in pet birds. They should consider
a diagnosis of AC for any lethargic
bird that has nonspecific signs of
illness, especially if the bird was
purchased recently. If AC is suspected,
the veterinarian should submit appropriate
laboratory specimens to a veterinary
diagnostic laboratory to confirm the
diagnosis. The laboratories and attending
veterinarians should follow local
and state regulations or guidelines
regarding reporting of cases. Veterinarians
should work closely with authorities
who conduct investigations in their
jurisdictions. When appropriate, veterinarians
should inform clients that infected
birds should be isolated and treated.
In addition, they should educate clients
about the public health hazard posed
by AC and the appropriate precautions
that should be taken to avoid transmission.
Quarantine of birds--The appropriate
animal and public health authorities
may issue a quarantine for all affected
and susceptible birds on premises
where AC has been identified. The
purpose of imposing a quarantine is
not to discourage disease reporting,
but to prevent further disease transmission.
Because of the severe economic impact
of quarantines, reasonable economic
options should be made available to
the owners and operators of pet stores.
For example, with the approval of
state or local authorities, the owner
of quarantined birds may choose to
treat the birds in a separate quarantine
area to prevent exposure to the public
and other birds, sell the birds if
they have completed at least 7 days
of treatment provided that the new
owner agrees in writing to continue
the quarantine and treatment and is
informed of the disease hazards, or
euthanatize infected birds. After
completion of the treatment or removal
of birds, a quarantine can be lifted
when the infected premises are thoroughly
cleaned and disinfected. The area
can then be restocked with birds.
Bird importation--The USDA-Animal
and Plant Health Inspection Service
Veterinary Services, regulates the
importation of pet birds to ensure
that exotic poultry diseases are not
introduced into the United States.
These regulations are set forth in
the Code of Federal Regulations, Title
9, Chapter 1.3 Because of smuggling
of pet birds, these import measures
do not guarantee that AC cannot enter
the United States. In general, current
USDA regulations regarding the importation
of birds include the following requirements:
Before shipping birds, the importer
must obtain an import permit from
the USDA and a health certificate
issued and/or endorsed by a veterinarian
of the national government of the
exporting country. A USDA veterinary
inspection must be conducted at the
first port of entry in the United
States, and a quarantine must be imposed
for a minimum of 30 days at a USDA-approved
facility to determine whether the
birds are free of evidence of communicable
poultry diseases. In addition, birds
must be tested to ensure they are
free of exotic Newcastle Disease and
pathogenic avian influenza. Psittacine
birds must receive a balanced, medicated
feed ration containing > 1% chlortetracycline
(CTC) with < 0.7% calcium for the
entire 30-day quarantine period as
a precautionary measure against AC.
The USDA recommends that importers
continue CTC prophylactic treatment
of psittacine birds for an additional
15 days (ie, 45 continuous days).
Local and state epidemiologic investigations--Public
or animal health authorities at the
local or state levels may need to
conduct epidemiologic investigations
to help control transmission of C.
psittaci to humans and birds. An epidemiologic
investigation should be initiated
if a bird in which AC is probable
or has been confirmed was procured
from a pet store, breeder, or dealer
within 60 days of the onset of signs
of illness, psittacosis is probable
or has been confirmed in a person,
or several birds in which AC is suspected
have been identified from the same
source. Other situations may be investigated
at the discretion of the appropriate
local or state public health departments
or animal health authorities. Investigations
involving a recently purchased bird
should include a visit to the site
where the infected bird is located
and identification of the location
where the bird was originally procured
(eg, pet shop, dealer, breeder, or
quarantine station). During such investigations,
authorities should consider documenting
the number and types of birds involved,
the health status of potentially affected
people and birds, locations of facilities
where birds were housed, relevant
ventilation-related factors, treatment
protocol, and source of medicated
feed, if such treatment is initiated.
To help identify multistate outbreaks
of AC, local and state authorities
should report suspected outbreaks
to the Respiratory Diseases Branch,
Division of Bacterial and Mycotic
Diseases, National Center for Infectious
Diseases, CDC, (404) 639-2215.
Additional Information on Chlamydiosis--
Flammer K. Chlamydia. In: Altman RB,
Clubb SL, Dorrestein GM, eds. Avian
medicine and surgery. Philadelphia:
WB Saunders Co, 1997;364-379.
Fudge AM. A review of methods to
detect Chlamydia psittaci in avian
patients. J Avian Med Surg 1997;11:153-165.
Fudge AM. Avian chlamydiosis. In:
Rosskopf WJ Jr, Woerpel RW, eds. Diseases
of cage and aviary birds. Baltimore:
The Williams & Wilkins Co, 1996;572-585.
Gelach H. Chlamydia. In: Ritchie
BW, Harrison GJ, Harrison LR, eds.
Avian medicine: principles and application.
Lake Worth, FL: Wingers Publishing,
1994;984-996.
Messmer TO, Skelton SK, Moroney JF,
et al. Application of a nested multiplex
PCR to psittacosis outbreaks. J Clinical
Microbiol 1997;35:2043-2046.
Schaffner W. Birds of a feather--do
they flock together? Infect Control
Hosp Epidemiol 1997;18:162-164.
Schlossberg D. Chlamydia psittaci
(psittacosis). In: Mandell GL, Bennett
JE, Dolin R, eds. Mandell, Douglas
and Bennett's principles and practice
of infectious diseases. 4th ed. New
York: Churchill Livingstone, 1995:1693-1696.
References. US Department of Health
and Human Services--Centers for Disease
Control and Prevention. Summary of
notifiable diseases, United States,
1997. MMWR CDC Surveill Summ 1998;46:3-13.
US Department of Health and Human
Services--Centers for Disease Control
and Prevention. Case definitions for
infectious conditions under public
health surveillance. MMWR CDC Surveill
Summ 1997;46:27. USDA-Animal and Plant
Health Inspection Service. Importation
of certain animals, birds, and poultry,
and certain animal, bird, and poultry
products; requirements for means of
conveyance and shipping containers.
In: Code of federal regulations. Washington
DC: USDA-Animal and Plant Health Inspection
Service, 1997;Title 9(Part 92):310-429.
Appendix 1 Laboratories that accept
specimens of human origin to confirm
psittacosis and the type of test(s)
that they perform. Other sources may
be available Respiratory Diseases
Laboratory Section, Microimmunofluorescence
(MIF), Centers for Disease Control
and Prevention, Atlanta, Ga (404)
639-3563 Complement fixation (CF),
Culture, Polymerase chain reaction
(PCR)> Microbiology Research Labs,
Cypress, Calif (800) 445-4032 Immunofluorescence
(IFA), PCR Labcorp Services, Burlington,
NC (800) 334-5161 Culture Specialty
Labs, Santa Monica, Calif (800) 421-4449
MIF Appendix 2 Methods for diagnosing
avian chlamydiosis (AC)
Histologic findings--In birds with
AC, cloudy air sacs and a large liver
and spleen usually are found, but
there is no gross lesion that is pathognomonic.
Chromatic or immunologic staining
of tissue-impression smears can be
used to identify organisms.
Culture--Isolation of Chlamydia psittaci
from the spleen, liver, air sacs,
pericardium, heart, or intestines
is the optimal means of verifying
the diagnosis. Chlamydial organisms
are obligate intracellular bacteria
that require tissue culture or mice
or chick embryos for growth. Specialized
laboratory facilities and training
are necessary for reliable identification
of chlamydial isolates and adequate
protection of microbiologists. Consequently,
few laboratories perform chlamydial
cultures. Depending on which clinical
signs birds have, cloacal and choanal
swab specimens should be obtained,
refrigerated, and sent to the laboratory
on ice, but not frozen. Proper handling
of specimens is critical for maintaining
viability of organisms for culture,
and a special transport medium is
required. Veterinarians should contact
their diagnostic laboratory for procedures
for submission of specimens. Live
birds that are tested for C. psittaci
may not shed the organism daily. Therefore,
to reduce laboratory costs, serial
specimens should be obtained for 3
to 5 consecutive days and pooled before
being cultured. Liver and spleen are
the preferred tissues to obtain at
necropsy for isolation of C. psittaci.
Use of culture methods is recommended
if legal actions may result from cases
of AC, thereby avoiding limitations
associated with use of other tests.
Antibody testing--A notable problem
with serologic testing is interpretation
of results. A positive result is evidence
that the bird was infected by C. psittaci
in the past, but it does not prove
that the bird has active disease.
Results may be falsely negative in
birds with acute infection if samples
are obtained before seroconversion.
Treatment with an antimicrobial agent
may diminish the antibody response.
Because of the diversity of reactions
when used with immunoglobulins from
various avian species, one testing
method may not be adequate to detect
AC. Therefore, use of antibody and
antigen detection methods is recommended,
particularly when only one bird is
tested. When samples are obtained
from one bird, serologic testing is
most useful if signs of disease and
history of the flock or aviary are
considered and serologic results are
compared to WBC counts and liver enzyme
activities. A greater than fourfold
increase in titer of paired samples
or a combination of a titer and antigen
identification is needed to confirm
a diagnosis of AC.
Direct CF--Direct CF is more sensitive
to antibody activity than agglutination
methods are. A commercial antigen
is not available. False-negative results
are possible in specimens from small
psittacine birds (eg, budgerigars,
young African Grey parrots, and lovebirds).
High titers may persist after treatment
and complicate interpretation of subsequent
tests. Modified direct CF is more
sensitive than direct CF. Elementary-body
agglutination (EBA)--The EBA test
is commercially available and can
detect early infection. Titers . 1:
10 in budgerigars, cockatiels, and
lovebirds and titers . 1:20 in larger
birds indicate current infection.
However, positive titers may persist
after treatment is completed, and
EBA is performed by only one US laboratory.
Immunofluorescent staining--Monoclonal
or polyclonal antibodies, fluorescein-staining
techniques, and fluorescent microscopy
are used to identify infectious agents
in impression smears from dead birds.
When used with cloacal or fecal smears,
this test has a sensitivity and specificity
that are questioned by some authorities.
The test is most useful if the bird
is shedding antigen. Its advantages
are that it gives rapid results and
does not require live, viable organisms.
Laboratory experience is important
for accurate interpretation of immunofluorescent
stains.
ELISA--An enzyme-linked immunosorbent
assay (ie, ELISA) used to identify
C. psittaci was originally developed
for identification of the lipopolysaccharide
antigen on C trachomatis, a human
pathogen. The sensitivity and specificity
of these tests for identifying C.
psittaci are not known. Although the
test is most useful in clinically
ill birds, the sensitivity may be
low in birds that do not have clinical
signs, because chlamydial organisms
are intermittently shed in birds.
Moreover, a few results may be false-positive
because of cross-reaction with other
bacteria. Results must be evaluated
in conjunction with clinical findings.
If a bird has a positive ELISA result
but is clinically healthy, the veterinarian
should attempt to verify that the
bird is shedding antigen through isolation
of the organism. When a clinically
ill bird has a negative ELISA result,
a diagnosis of AC cannot be excluded
without further testing (eg, isolation,
serologic or fluorescent-antibody
testing).
PCR--A number of laboratories offer
diagnostic testing for C. psittaci
using PCR technology; however, few
tests have been validated. The PCR
promises to be sensitive and specific
for detection of target DNA sequences
in the type of samples collected from
birds (eg, blood, cloacal and choanal
swabs). Results of tests that have
not been validated for use in birds
may be difficult to interpret.
Additional tests--Additional diagnostic
techniques are in use or under development
(eg, MIF and Immunocomb). Readers
are encouraged to research peer-reviewed
reports on such tests before use.
Laboratories that test for C. psittaci--Many
state diagnostic laboratories and
veterinary colleges perform routine
chlamydial diagnostic tests. Additional
laboratories and the type(s) of test
they perform are listed below; others
may be available.
Inclusion in this list does not imply
endorsement by the Psittacosis Compendium
Committee. Animal Health Diagnostic
Laboratory, Mich (517) 353-1683 ELISA,
PCR, CF AnTec Diagnostics, NJ (800)
745-4725 Monoclonal immunoassay Avian
and Exotic Animal Labs, Calif (310)
542-6556 PCR, CF California Avian
Laboratory, Calif (800) 783-2473 IFA
Comparative Pathology Laboratory,
Fla (800) 596-7390 IFA, ELISA Infectious
Diseases Laboratory, Ga (706) 542-5812
DNA probe Marshfield Laboratory, Wis
(800) 222-5835 Culture, EBA, CF Research
Associates Laboratory, Ohio (513)
248-4700 PCR Texas Veterinary Medical
Laboratory, Tex (409) 845-3414 Culture,
PCR, Gimen, EBA, CF Appendix 3
Treatment options for pet birds with
AC The following are established treatments
for AC. Although these protocols usually
are successful, knowledge in this
area is evolving, and no treatment
protocol guarantees safe treatment
or complete elimination of infection.
Therefore, treatment should be supervised
by a licensed veterinarian. Birds
with AC should be treated for 45 days,
except as noted.
Medicated feed--Medicated feed should
be the only food provided to birds
during the entire treatment. Birds'
acceptance of medicated feed is variable.
Thus, food consumption should be monitored.
Acceptance may be enhanced first by
adapting the bird to a similar, nonmedicated
diet. Treatment begins when the bird
accepts the medicated feed as the
sole food in its diet. The following
options are available: Medicated mash
diets (ie, . 1% chlortetracycline
[CTC] with , 0 .7% calcium) prepared
with corn, rice, and hen's scratch.
White millet seed impregnated with
0.5 mg CTC/g of seed (Keet Life, Hartz
Mountain, Secaucus, NJ) for budgerigar
parakeets and finches only. It should
be used for 30 days. Pellets and extruded
products containing 1% CTC are available
and appropriate for use with most
pet birds. Select a pellet size appropriate
for the size of bird being treated.
A special diet might be necessary
for lories and lorikeets, which feed
on nectar and fruit.
Oral or parenteral treatments--Doxycycline
is the drug of choice for oral treatment;
the monohydrate or calcium-syrup formulation
may be used. On the basis of nonpeer-reviewed
studies, dosage recommendations are
40 to 50 mg/kg (18.2 to 22.7 mg/lb)
of body weight orally once a day for
cockatiels, Senegal parrots, and blue-fronted
and orange-winged Amazon parrots;
and 25 mg/kg (11.4 mg/lb) orally once
a day for African Grey parrots, Goffin's
cockatoos, blue and gold macaws, and
green-winged macaws. Precise dosages
cannot be extrapolated for species
in which this drug has not been tested;
however, 25 to 30 mg/kg (11.4 to 13.6
mg/lb) orally once a day is the recommended
initial dosage for cockatoos and macaws,
and 25 to 50 mg/kg (11.4 to 22.7 mg/lb)
orally once a day is recommended for
other psittacine species. If the bird
regurgitates the drug, another treatment
method should be used. Intramuscular
injection of doxycycline into the
pectoral muscle is often the easiest
method of treatment, but not all injectable
formulations are suitable for IM injection.
All available formulations can cause
irritation at the injection site.
One formulation (Vibrovenos, Pfizer
Laboratories, London, Ontario, Canada)
is available in Canada and Europe,
and it is effective if administered
at doses of 75 to 100 mg/kg (34 to
45.5 mg/lb) IM every 5 to 7 days for
the first 4 weeks and every 5 days
thereafter for the duration of treatment.
Anecdotal reports indicate that pharmacist-compounded,
injectable doxycycline products have
been used successfully in the United
States. However, data are insufficient
to determine precise dosage schedules.
The injectable hyclate formulation
labeled for IV use in humans in the
United States is not suitable for
IM use in birds, because severe tissue
reactions will develop at the site
of injection. Limited information
exists on use of an injectable, long-acting
oxytetracycline product (LA-200; Pfizer
Laboratories, Exton, Penn). Current
dosage recommendations are 75 mg/kg
(34 mg/lb) SC every 3 days in Goffin's
cockatoos, blue-fronted and orange-winged
Amazon parrots, and blue and gold
macaws. This dosage may be suitable
for but has not been tested on other
species. This product causes irritation
at the site of injection, and it is
best used to initiate treatment in
ill birds or those that are reluctant
to eat. After the bird's condition
stabilizes, it should be switched
to another form of treatment to minimize
muscle irritation caused by repeated
injections of oxytetracycline. Treatment
protocols using late-generation macrolides,
pharmacist-compounded injectable doxycycline,
and doxycycline-medicated feed and
water are under investigation. Information
about these treatment protocols may
be available in the scientific literature
or from avian veterinary specialists.
Sources of medicated feeds--These
are not listed as an endorsement of
said company or products. Other sources
may be available. Avi-Sci Inc: 4477
S Williams Rd, St Johns, MI 48879,
(800) 942-3438; fax: (517) 224-9227.
Rolf C. Hagen (Tropican): PO Box 9107,
Mansfield, MA 02048, (800) 225-2700;
(888) BY HAGEN. Lake's Unlimited Inc:
639 Stryker Ave, St Paul, MN 55107,
(800) 634-2473. Pretty Bird International,
Inc, 5810 Stacy Trl, PO Box 177, Stacy,
MN 55079, (803) 356-5020. Roudybush:
PO Box 908, Templeton, CA 93456, (800)
326-1726. Wardley VMX, Hartz Mountain
Corp: 700 Frank E Rogers Blvd, Harrison,
NJ 07029, (800) 922-0537. Ziegler
Brothers, Inc: PO Box 95, Gardners,
PA 17324-0095, (800) 841-6800. [-]
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