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Copyright Notice & Disclaimer
Statement
Epidemiologic investigations may be necessary to assist in controlling the
transmission of C. psittaci in birds and humans. An epidemiologic
investigation should be initiated if:
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a bird that has confirmed or probable AC was procured from a pet store,
breeder, or dealer within 60 days of the onset of its signs
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a human has confirmed or probable psittacosis, or
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there are several suspect avian cases from the same source
Other situations may be investigated at the discretion of the appropriate
local or state public or animal health authorities.
Investigations involving recently purchased birds should include a visit to
the site where the infected bird is located and identification of the location
where the bird was originally procured (e.g., pet shops, dealers, breeders, and
quarantine stations). In conducting investigations, important considerations may
include documenting the number and type(s) of birds involved, the health status
of potentially affected persons and birds, locations of facilities where birds
were housed, relevant ventilation-related factors, the treatment protocol, and
the source of medicated feed, if such treatment is initiated. To facilitate
identification of multistate outbreaks of C. psittaci infection, 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, telephone (404) 639-2215.
References
1. Us Department of Agriculture, 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.
CFR Title 9 Part 92. 101-7, Jan. 1, 1997.
2. CDC. Summary of notifiable
diseases, United States, 1995. MMWR 1995;44(53):74-7.
3. CDC. Case
definitions for infectious conditions under public health surveillance. MMWR
1997;46(No. RR-10):27.
Additional Information
Flammer K. Chlamydia In: Altman RB, Clubb SL,
Dorrestein GM, Quesenberry K, eds. Avian Medicine and Surgery. Philadelphia: W.B. Saunders Co., 1997:364- 79.
Fudge AM. Avian
chlamydiosis. In: Rosskopf WJ, Woerpel RW, eds. Diseases of cage and aviary birds. Baltimore: Williams
& Wilkins, 1996:572-85.
Gelach H. Chlamydia. In: Ritchie BW, Harrison GJ, Harrison
LR, eds. Avian medicine, principles and applications. Lake Worth,
FL: Wingers Publishing, 1994:984-96.
Schlossberg D. Chlamydia psittaci
(psittacosis). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and practice
of infectious disease, 4th ed. New York: CHurchill Livingstone, 1995:1693-6.
Schaffner W. Birds of a feather--do they flock together? Infect Control Hosp
Epidemiol 1997;18:162-4.
In birds that have avian chlamydiosis (AC), cloudy air sacs and enlarged
liver and spleen are usually observed, but no specific, gross lesion is
pathognomonic. The chromatic or immunologic staining of tissue-impression smears
can be used to identify organisms.
Isolation of the etiologic agent, Chlamydia psittaci, from spleen,
liver, air sacs, pericardium, heart, or intestines is the optimal diagnostic
verification. Chlamydia organisms are obligate intracellular bacteria
that must be isolated in tissue culture, mice, or chick embryos. Specialized
laboratory facilities and training are necessary both for reliable
identification of chlamydial isolates and for protection of the microbiologists.
Consequently, few laboratories perform chlamydial cultures.
In live birds, depending on which clinical signs they exhibit, combined
cloacal and choanal-swab specimens should be collected, refrigerated, and sent
to the laboratory packed in ice, but not frozen. The proper handling of samples
is critical for maintaining the viability of organisms for culture, and a
special transport medium is required. Veterinarians should contact their
specific diagnostic laboratory for procedures required for submission of
specimens for isolation.
Live birds being screened for C. psittaci may not shed the
microorganism daily. Therefore, to reduce laboratory costs, serial specimens
should be collected for 3-5 consecutive days and pooled before being cultured.
Tissue samples from the liver and spleen are the preferred necropsy specimens
for isolation of C. psittaci. When legal actions may result from
chlamydiosis cases, use of culture is recommended to avoid limitations
associated with other tests.
A major problem with serologic testing is the interpretation of results. A
positive serologic test result is evidence that the bird was infected by C.
psittaci in the past, but it does not prove that the bird currently has
active disease. False-negative results may occur for birds that have acute
infection when they are sampled before seroconversion. Antibiotic treatment may
diminish the antibody response.
A single testing method may not be adequate because of the diversity of
reactions with immunoglobulins from the various avian species. Therefore, the
use of a combination of antibody- and antigen-detection methods for the
diagnosis of chlamydiosis is recommended, particularly when only one bird is
tested. When specimens are obtained from a single bird, serologic testing is
most useful when
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signs of disease and the history of the flock or aviary are considered and
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serological results are compared with the white blood cell counts and
liver-enzyme activities. Either 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 chlamydiosis.
Some of the advantages/disadvantages of several of the serologic tests for
antibodies are as follows:
Direct CF is more sensitive to antibody activity than are agglutination
methods. No commercial antigen is available. False-negative results are possible
in specimens from small psittacine birds (e.g., 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.
EBA is commercially available and can detect early infection. Titers >10
in budgerigars, cockatiels, and lovebirds and titers of >20 in larger birds
are interpreted by the laboratory as indicating current infection. However,
positive titers may persist after treatment is completed, and EBA is performed
only by a single laboratory.
Monoclonal or polyclonal antibodies, fluorescein-staining techniques, and
fluorescent microscopy are used to identify elementary bodies (i.e., infectious
agents) in impression smears from dead birds. When used with cloacal or fecal
smears, the test sensitivity and specificity 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 tests (i.e., IDEIA®) currently being used to identify C.
psittaci were originally developed for identification of the
lipopolysaccharide antigen on C. trachomatis, which is a human pathogen.
The sensitivity and specificity of these tests for identifying C.
psittaci are not precisely known. While the test is most useful in
clinically ill birds, the sensitivity may be low in asymptomatic birds because
of intermittent shedding. Moreover, some tests may be falsely positive because
of cross-reaction with other bacteria. The test results must be evaluated in
conjunction with other 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 (e.g., isolation, serologic testing, or fluorescent
antibody).
Additional diagnostic techniques are in use or under development, including
polymerase chain reaction (PCR). Readers are encouraged to research pre-reviewed
reports on such tests prior to use.
Many state diagnostic laboratories and veterinary colleges perform routine
chlamydial diagnostics. Additional laboratories are listed below; others may be
available. Inclusion in this list does not imply endorsement from the
Psittacosis Compendium.
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California Avian Laboratory
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800-783-2473
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FA
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Labcorp Veterinary Services
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800-334-5161
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Culture
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Marshfield Laboratories
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800-222-5835
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Culture, EBA (TX), CF (TX)
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Avian and Exotic Animal Laboratories
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310-542-6556
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PCR, DC (TX)
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Animal Health Diagnostic Laboratory
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517-353-1683
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EIA (Unipath), PCR, CF (Ames)
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Texas Veterinary Medical Laboratory
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409-845-3414
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Culture, PCR, EBA, CF
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Comparative Pathology Laboratory
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600-596-7390
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IFA serology, EIA (Unipath)
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Research Associates Laboratory
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513-248-4700
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PCR
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Return
to Psittacosis Index
Veterinarians can choose several methods for treating avian chlamydiosis
(AC). Although these protocols are usually successful, knowledge in this area is
evolving, and no treatment protocol guarantees safe treatment or complete
elimination of infection by the etiologic agent Chlamydia psittaci in all
avian species. Therefore, treatment should be supervised by a licensed
veterinarian.
Several methods of treating AC exist. All birds should be treated for a
period of 45 days, except as noted below. The following are established as
effective treatments:
The medicated feed should be the only food provided to the birds during the
entire treatment. Birds' acceptance of medicated feed is variable. Thus, food
consumption should be monitored. Acceptance may be enhanced by first adapting
the birds to a similar, nonmedicated diet. The treatment begins when the birds
accept the medicated feed as the sole food in their diet.
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Medicated mash diets (i.e., >1% chlortetracycline [CTC] with <0.7%
calcium) prepared with corn can be used.*
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White millet seed, impregnated with 0.5 mg CTC/g of seed, may be used for
budgerigar parakeets and finches only. It should be used for 30 days (Keet
Life®, Hartz Mountain is the only manufacturer).
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Pellets and extruded products containing 1% CTC may be used. They are
available and appropriate for use in most companion birds. A pellet size
should be selected that is appropriate for the size of bird being treated.
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A special diet may be necessary for birds belonging to a subfamily of
psittacine birds know as Lariidae (i.e., lories and lorikeets) that feed on
nectar and fruit in the wild.
Three such treatments are provided.
Oral doxycycline. Doxyclycline is the drug of choice for oral
treatment; either the monohydrate or calcium-syrup formulations may be used.
Based on nonpeer-reviewed studies, dosage recommendations are as follows:
40-50 mg/kg by mouth once a day for cockatiels, Senegal parrots, and
blue-fronted and orange-winged Amazon parrots; and 25 mg/kg by mouth once a
day for African grey parrots, Goffin's cockatoos, and blue and gold and
green-winged macaws. Precise dosages cannot be extrapolated for untested
species; however, 25-30 mg/kg administered by mouth once a day is the
recommended starting dose in cockatoos and macaws and 25-50 mg/kg by mouth
once a day is the recommended starting dose in other psittacine species. If
the bird regurgitates the drug, another treatment method should be used.
Injectable doxycycline. Intramuscular (IM) injection into the
pectoral muscle is often the easiest method of treatment, but not all
injectable doxycycline formulations are suitable for IM injection. All
currently available formulations may cause irritation at the injection site.
The Vibrovenos® formulation (Pfizer Laboratories) is available in Europe and
Canada and is effective if administered at doese of 75-100 mg/kg IM every 5-7
days for the first 4 weeks and subsequently every 5 days for the duration of
the treatment. Anecdotal reports exist of the successful use of
pharmacist-compounded injectable-doxycycline products in the United States.
However, data are insufficient to determine precise dosage schedules. The
injectable-hyclate formulation labeled for intravenous (IV) use in humans in
the United States is not suitable for IM use, because severe tissue reactions
will occur at the site of injection.
Injectable oxytetracycline. Limited information exists for the use
of an injectable, long-acting oxytetracycline product (LA-200®; Pfizer
Laboratories). Current dosage recommendations are as follows: subcutaneous
injection of 75 mg/kg every 3 days in Goffin's cockatoos, blue-fronted and
orange-winged Amazon parrots, and blue and gold macaws. This dose may be
suitable for other species but has not been tested. This product causes
irritation at the site of injection and is best used to initiate treatment in
ill birds or those that are reluctant to eat. After stabilization with
oxytetracycline treatment, the birds should be switched to another form of
treatment to reduce the muscle irritation that is caused by repeated
oxytetracycline injection.
Experimental methods
Treatment protocols using fluoroquinolones, late-generation
macrolides,
pharmacist-compounded injectable doxycycline, and doxycycline-medicated feed
are currently being investigated. Information about these treatment protocols
may be available in the scientific literature or from avian veterinary
specialists.
These are not listed as an endorsement of said company or
products. Other sources may be available.
Avi-Sci, Inc.; P.O. Box 598; Okemos, MI 48805; 800-942-4800
The Bird
Company; 619-748-3847
Hartz Mountain Corp.; 700 Frank E. Rogers Blve;
Harrison, NJ 07029; 201-481-4800
Lafeber Company; RR 2; Odell, IL 60460;
800-842-6445
Kaytee Products, Inc.; P.O. Box 230; 292 East Grand St.;
Chilton, WI 53014; 800-669-9580; 800-356-5020
Pretty Bird International,
Inc.; 5810 Stacy Trail; Stacy MN 55079; 800-356-5020
Rolf C. Hagen; P.O.
Box 9107; Mansfield, MA 02048; 800-225-2700/2701
Roudybush; P.O. Box 908;
Templeton, CA 93465; 800-326-1726; 805-434-0303
Ziegler Brothers, Inc.;
P.O. Box 95; Gardners, PA 17324-0095; 800-841-6800
*The recommended recipe is 2 pounds of rice, 2 pounds of hen
scratch feed, and 3 pints of water, cooded for 15 minutes at full pressure in
a pressure cooker. Add 10 mg chlortetracycline/g of feed after the cooked feed
cools. Note that birds may find this diet unpalatable and may not accept it.
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