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Compendium of measures to control Chlamydophila psittaci (formerly Chlamydia psittaci) infection among humans (psittacosis) and pet birds, 2005
Kathleen A. Smith, DVM, MPH; Kristy K. Bradley, DVM, MPH, DACVPM;
Mary G. Stobierski, DVM, MPH, DACVPM; Leslie A. Tengelsen, PhD, DVM
with no identified leisure time or occupational risk can
Psittacosis, also known as parrot fever and ornithosis, is
a bacterial infection of humans that can cause severe
In this compendium, C psittaci infection in birds is
pneumonia and other serious health problems. It is
referred to as avian chlamydiosis. Chlamydial organ-
caused by Chlamydophila psittaci, formerly known as
isms have been isolated from approximately 100 bird
Chlamydia psittaci. From 1988 through 2003, 935 human
species but are most commonly identified in psittacine
cases of psittacosis were reported to the CDC and most
(parrot-type) birds, especially cockatiels and budgeri-
resulted from exposure to infected pet birds, usually
gars, commonly known as parakeets or budgies.
cockatiels, parakeets, parrots, and macaws. In birds, Cpsittaci infection is referred to as avian chlamydiosis.
Among caged, nonpsittacine birds, infection with
Infected birds shed the bacteria through feces and nasal
Chlamydiaceae organisms occurs most frequently in
discharges, and humans become infected from expo-
pigeons and doves. Avian chlamydiosis is less fre-
sure to these materials. This compendium provides infor-
quently diagnosed in canaries and finches. The recom-
mation about psittacosis and avian chlamydiosis to pub-
mendations in this compendium provide standardized
lic health officials, physicians, veterinarians, the pet bird
procedures for controlling avian chlamydiosis in the
industry, and others concerned with controlling these
pet bird population, an essential step in efforts to con-
diseases and protecting public health. The recommen-
trol psittacosis among humans. This compendium is
dations in this compendium provide standardized proce-
intended to guide public health officials, physicians,
dures for controlling avian chlamydiosis in birds, a vitalstep to protecting human health. This document will be
veterinarians, the pet bird industry, and others con-
cerned with the control of C psittaci infection and theprotection of public health. Chlamydophila psittaci (formerly known as Chlamydia psittaci) is a member of the family Chlamydiaceae.1 It
Infection in Humans (Psittacosis)
is a bacterium that can be transmitted from pet birds to
Transmission—The disease resulting from
humans. In humans, the resulting infection is referred to
C psittaci infection in humans is called psittacosis, and
as psittacosis (also known as parrot fever and ornitho-
most infections are typically acquired from exposure to
sis). Psittacosis typically causes influenza-like symp-
pet psittacine birds. However, transmission has been
toms and can lead to severe pneumonia and nonrespira-
documented from poultry and free-ranging birds,
tory health problems. With appropriate treatment, the
including doves, pigeons, birds of prey, and shore birds.
disease is rarely fatal. From 1988 through 2003, the
Infection with C psittaci usually occurs when a person
CDC received reports of 935 cases of psittacosis,2 which
inhales organisms that have been aerosolized from
is an underrepresentation of the actual number of cases.
dried feces or respiratory tract secretions of infected
Most human cases were associated with exposure to pet
birds. Other means of exposure include mouth-to-beak
birds. Other persons at risk include pigeon fanciers and
contact and handling infected birds’ plumage and tis-
persons in specific occupations (eg, employees in poul-
sues. Even brief exposures can lead to symptomatic
try slaughtering and processing plants, veterinarians,
infection; therefore, certain patients with psittacosis
veterinary technicians, laboratory workers, workers in
might not recall or report having any contact with birds.
avian quarantine stations, farmers, wildlife rehabilita-
Mammals occasionally transmit Chlamydiaceae
tors, and zoo workers). Because human infection can
organisms to humans. Certain chlamydial species
result from brief, passing exposure to infected birds or
infect sheep, goats, and cattle, causing chronic infec-
their contaminated excretions or secretions, persons
tion of the reproductive tract, placental insufficiency,
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and abortion. Those species are transmitted to humans
greater increase in antibodies against C psittaci detect-
when humans are exposed to the birth fluids and pla-
ed by complement fixation (CF) or microimmunoflu-
centas of infected animals. Another chlamydial species,
orescence (MIF) to a reciprocal titer of ≥ 32 between
the feline keratoconjunctivitis agent, typically causes
paired acute- and convalescent-phase serum samples,
rhinitis and conjunctivitis in cats. Transmission of this
or immunoglobulin M antibodies against C psittaci are
species from cats to humans may be underreported.
detected by MIF to a reciprocal titer of ≥ 16. A patient
Person-to-person transmission has been suggested
is considered to have a probable case of psittacosis if
but not proven.3 Standard infection-control precau-
clinical illness is compatible with psittacosis and the
tions are sufficient for humans with psittacosis, and
patient is epidemiologically linked to a confirmed
specific isolation procedures (eg, private room, nega-
human case of psittacosis or the patient has supportive
tive pressure air flow, and masks) are not indicated.
serologic (eg, a single antibody titer of ≥ 32, detected
by CF or MIF, in at least 1 serum sample obtained after
Clinical signs and symptoms—Onset of illness typ-
onset of symptoms). Updated case definitions may be
ically follows an incubation period of 5 to 14 days, but
longer periods have been reported. The severity of thedisease ranges from inapparent illness to systemic illness
Diagnosis—Most diagnoses are established by use
with severe pneumonia. Before antimicrobial agents
of MIF to test for antibodies against C psittaci in paired
were available, 15% to 20% of humans with sera. The MIF is more sensitive and specific than theC psittaci infection died. However, < 1% of properly
previously used CF tests; however, there is still some
treated humans now die as a result of the infection.
cross-reactivity with other chlamydiae, such as C pneu-
Humans with symptomatic infection typically have
moniae, C trachomatis, and C felis. Polymerase chain
abrupt onset of fever, chills, headache, malaise, and
reaction (PCR) assays can be used to distinguish
myalgia. They usually develop a nonproductive cough
C psittaci infection from infection with other chlamy-
that can be accompanied by breathing difficulty and
dial species. Acute-phase serum samples should be
chest tightness. A pulse-temperature dissociation (fever
obtained as soon as possible after onset of symptoms,
without increased pulse rate), enlarged spleen, and non-
and convalescent-phase serum samples should be
specific rash are sometimes observed and are suggestive
obtained 2 weeks after the first sample. Because
of psittacosis in patients with community-acquired
antimicrobial treatment can delay or diminish the anti-
pneumonia. Auscultatory findings can underestimate
body response, a third serum sample might help con-
the extent of pulmonary involvement. Radiographic
firm the diagnosis. All sera should be tested simultane-
findings include lobar or interstitial infiltrates. The dif-
ously at the same laboratory. The infectious agent can
ferential diagnosis of pneumonia caused by psittacosis
also be isolated from the patient’s sputum, pleural
includes infection with Coxiella burnetii, Mycoplasma
fluid, or clotted blood during acute illness and before
pneumoniae, Legionella spp, other Chlamydiaceae, and
treatment with antimicrobial agents; however, culture
respiratory viruses such as influenza. Chlamydophila
of C psittaci is performed by few laboratories because
psittaci can affect organ systems other than the respira-
of technical difficulty and safety concerns.
tory tract and result in endocarditis, myocarditis, hepati-
Laboratories that test human specimens for
tis, arthritis, keratoconjunctivitis, and encephalitis. Chlamydiaceae—Information about laboratory testing
Severe illness with respiratory failure, thrombocytope-
is available from most state public health laboratories.
nia, hepatitis, and fetal death has been reported among
Few commercial laboratories have the capability to dif-
ferentiate chlamydial species. Certain laboratoriesaccept human specimens to confirm C psittaci infec-
Case definition—In 1997, the CDC and the
tion (Table 1). Other sources might be available.
Council of State and Territorial Epidemiologists pub-lished surveillance case definitions for confirmed and
Treatment—Tetracyclines are the drugs of choice.6
probable psittacosis for epidemiologic purposes.4
Most patients respond to orally administered treatment
These definitions should not be used as the sole crite-
(doxycycline [100 mg, q 12 h] or tetracycline
ria for establishing clinical diagnoses. A patient is con-
hydrochloride [500 mg, q 6 h]). For initial treatment of
sidered to have a confirmed case of psittacosis if clini-
severely ill patients, doxycycline hyclate can be admin-
cal illness is compatible with psittacosis and the case is
istered IV at a dosage of 4.4 mg/kg/d (2 mg/lb/d) divid-
laboratory confirmed by 1 of 3 methods: C psittaci is
ed into 2 infusions/d (up to 100 mg/dose). Remission
cultured from respiratory secretions, there is a 4-fold or
of symptoms usually is evident within 48 to 72 hours.
Table 1—Laboratories that test human specimens for Chlamydophila psittaci. Laboratory Tests performed* Telephone number
Respiratory Diseases, Laboratory Section, CDC,* Atlanta, Ga
Laboratory Corp of America, Burlington, NC
*CDC is not a commercial laboratory. MIF = Microimmunofluorescence. PCR = Polymerase chain reaction assay.
Vet Med Today: Public Veterinary Medicine
0215PVM revised.qxp 1/27/2005 11:28 AM Page 534
However, relapse can occur, and treatment must con-
sis in birds (Appendix 1). Treatment should be super-
tinue for at least 10 to 14 days after fever abates.
vised by a licensed veterinarian (Appendix 2).
Although in vivo efficacy has not been determined,macrolides are probably the best alternative agents in
Recommendations and Requirements
patients for whom tetracycline is contraindicated (eg,
Aviary and pet shop owners are encouraged to
children < 9 years of age and pregnant women).
implement recommendations such as those describedin the Model Aviary Program.17 Such programs encour-
Infection in Birds (Avian Chlamydiosis)
age disease prevention and improve animal health and
Transmission—Chlamydophila psittaci is excret-
ed in the feces and nasal discharges of infected birds. The organism is environmentally labile but can
Recommendations for controlling infection in
remain infectious for several months if protected by
humans and birds—To prevent transmission of
organic debris (eg, litter and feces). Some infected
C psittaci to humans and birds, specific control mea-
birds can appear healthy and shed the organism inter-
mittently. Shedding can be activated by stress factors,
' Protect persons at risk. Inform all persons in con-
including relocation, shipping, crowding, chilling,
tact with infected birds or contaminated materials
about the nature of the disease. Instruct them towear protective clothing, gloves, a disposable sur-
Clinical signs—The usual duration between expo-
gical cap, and an appropriately fitted respirator18
sure to C psittaci and onset of illness ranges from 3
with N95 or higher rating when cleaning cages or
days to several weeks. However, active disease can
handling infected birds. Surgical masks might not
appear with no identifiable exposure. Whether the bird
be effective in preventing transmission of
has acute or chronic signs of illness or dies depends on
C psittaci. When necropsies are performed on
the species of bird, virulence of the strain, infectious
potentially infected birds, wet the carcass with
dose, stress factors, age, and extent of treatment or pro-
detergent and water to prevent aerosolization of
infectious particles and work under a biological
Signs of avian chlamydiosis include lethargy,
anorexia, and ruffled feathers, similar to signs of other
' Maintain accurate records of all bird-related
systemic illnesses. Other signs include serous or
transactions for at least 1 year to aid in identify-
mucopurulent ocular or nasal discharge, diarrhea, and
ing sources of infected birds and potentially
excretion of green to yellow-green urates. Anorectic
exposed persons. Records should include the date
birds can produce sparse, dark green droppings, fol-
of purchase, species of birds purchased, individual
lowed by emaciation, dehydration, and death.
bird identification, source of birds, and any identi-
Case definition—A confirmed case of avian
fied illnesses or deaths among birds. In addition,
chlamydiosis is defined on the basis of at least 1 of 4
the seller should record the name, address, and
laboratory results, including isolation of C psittaci from
telephone number of the customer and individual
a clinical specimen, identification of chlamydial anti-
bird identification (eg, band or microchip num-
gen by use of immunofluorescence (fluorescent anti-
body testing) of the bird’s tissues, a ≥ 4-fold change in
Avoid purchasing or selling birds that have signs
serologic titer in 2 samples obtained from the bird at
of avian chlamydiosis. Signs include ocular or
least 2 weeks apart and assayed simultaneously at the
nasal discharge, diarrhea, or low body weight.
same laboratory, or identification of ChlamydiaceaeIsolate newly acquired, ill, or exposed birds.
within macrophages in smears stained with Gimenez
Isolation should include housing in a separate air
or Macchiavello stain or sections of the bird’s tissues.
space from other birds and noncaretakers. Isolate
A probable case of avian chlamydiosis is defined as
birds, including those that have been to shows,
compatible illness and at least 1 of 2 positive laborato-
exhibitions, fairs, and other events, for at least 30
ry results, including a single high serologic titer in 1 or
days, and test or prophylactically treat them before
more samples obtained after the onset of signs or detec-
tion of Chlamydiaceae antigen (identified by use of
Test birds before they are to be boarded or sold
ELISA, PCR, or fluorescent antibody) in feces, a cloacal
on consignment. House them in a room separate
swab specimen, or respiratory tract or ocular exudates.
A suspected case of avian chlamydiosis is defined
Practice preventive husbandry. Position cages to
as a compatible illness that is epidemiologically linked
prevent the transfer of fecal matter, feathers,
to another case in a human or bird but that is not lab-
food, and other materials from 1 cage to another.
oratory confirmed, a subclinical infection with a sin-
Do not stack cages, and be sure to use solid-sided
gle high serologic titer or detection of chlamydial anti-
cages or barriers if cages are adjoining. The bot-
gen, compatible illness with positive results from a
tom of the cage should be made of a wire mesh.
nonstandardized test or a new investigational test, or
Litter that will not produce dust (eg, newspapers)
compatible illness that is responsive to appropriate
should be placed underneath the mesh. Clean all
cages, food bowls, and water bowls daily. Soiledbowls should be emptied, cleaned with soap and
Diagnosis and treatment—Several diagnostic
water, rinsed, placed in a disinfectant solution,
methods are available for identifying avian chlamydio-
and rinsed again before reuse. Between occupan-
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0215PVM revised.qxp 1/27/2005 11:28 AM Page 535
cies by different birds, cages should be thorough-
' Observe the birds daily, and weigh them every 3 to
ly scrubbed with soap and water, disinfected, and
7 days. If the birds are not maintaining weight,
rinsed in clean running water. Exhaust ventila-
have them reevaluated by a veterinarian.
tion should be sufficient to prevent accumulation
' Avoid high dietary concentrations of calcium and
of aerosols and prevent cross-contamination of
other divalent cations because they inhibit the
absorption of tetracyclines. Remove oyster shell,
' Control the spread of infection. Isolate birds
requiring treatment. Rooms and cages where
' Isolate birds that are to be treated in clean,
infected birds were housed should be cleaned
immediately and disinfected thoroughly. When the
' Clean up all spilled food promptly; wash food and
cage is being cleaned, transfer the bird to a clean
cage. Thoroughly scrub the soiled cage with a
' Provide fresh water and appropriate vitamins daily.
detergent to remove all fecal debris, rinse the cage,
' Continue medication for the full treatment period to
disinfect it (allowing at least 5 minutes of contact
avoid relapses. Birds can appear clinically improved
with the disinfectant), and rerinse the cage to
and have reduced chlamydial shedding after 1 week.
remove the disinfectant. Discard all items that can-not be adequately disinfected (eg, wooden perch-
Responsibilities of bird owners, physicians,
es, ropes, nest material, and litter). Minimize the
and veterinarians—Humans exposed to birds with
circulation of feathers and dust by wet-mopping
avian chlamydiosis should seek medical attention if
the floor frequently with disinfectants and pre-
they develop influenza-like symptoms or other res-
venting air currents and drafts within the area.
piratory tract illnesses. The physician should con-
Reduce contamination from dust by spraying the
sider psittacosis in ill patients exposed to birds and
floor with a disinfectant or water before sweeping
collect specimens for laboratory analysis. Early and
it. Do not use a vacuum cleaner because it will
specific treatment for psittacosis should be initiated.
aerosolize infectious particles. Frequently remove
Most states require physicians to report cases of psit-
waste material from the cage (after moistening the
tacosis to the appropriate state or local public health
material), and burn or double-bag the waste for
authorities. Timely diagnosis and reporting can help
disposal. Care for healthy birds before handling
identify the source of infection and control the
spread of disease. Local and state authorities may
' Use disinfection measures. All surfaces should be
conduct epidemiologic investigations and institute
cleaned thoroughly before disinfection. Chlamydo-
additional disease control measures. Birds that are
phila psittaci is susceptible to most disinfectants
suspected sources of human infection should be
and detergents as well as heat; however, it is resis-
referred to veterinarians for evaluation and treat-
tant to acid and alkali. A 1:1,000 dilution of qua-
ment. Veterinarians should be aware that avian
ternary ammonium compounds (eg, Roccal or
chlamydiosis is not a rare disease among pet birds.
Zephiran) is effective, as are 70% isopropyl alco-
They should consider a diagnosis of avian chlamy-
hol, 1% Lysol, 1:100 dilution of household bleach
diosis for any lethargic bird that has nonspecific
(ie, 2.5 tablespoons/gallon), and chlorophenols.
signs of illness, especially if the bird was purchased
Many disinfectants are respiratory irritants and
recently. If avian chlamydiosis is suspected, the vet-
should be used in a well-ventilated area. Avoid
erinarian should submit appropriate laboratory
mixing disinfectants with any other product.
specimens to confirm the diagnosis. Laboratoriesand attending veterinarians should follow local and
Treatment and care of infected birds—All birds
state regulations or guidelines regarding case report-
with confirmed or probable avian chlamydiosis
ing. Veterinarians should work closely with authori-
should be isolated and treated, preferably under the
ties on investigations and inform clients that infect-
supervision of a veterinarian (Appendix 2). Birds
ed birds should be isolated and treated. In addition,
with suspected avian chlamydiosis or birds previ-
they should educate clients about the public health
ously exposed to avian chlamydiosis should be iso-
hazard posed by avian chlamydiosis and the appro-
lated and retested or treated. Because treated birds
priate precautions that should be taken to avoid the
can be reinfected, they should not be exposed to
untreated birds or other potential sources of infec-
Local and state epidemiologic investigations—
tion. To prevent reinfection, contaminated aviaries
Public or animal health authorities at the local or state
should be thoroughly cleaned and disinfected sever-
level may need to conduct epidemiologic investiga-
al days before treatment ends. No avian chlamydio-
tions to help control the transmission of C psittaci to
sis vaccines are available. General recommendations
humans and birds. An epidemiologic investigation
should be followed when treating and caring for
should be initiated if a bird with confirmed or probable
birds with confirmed, probable, or suspected avian
avian chlamydiosis was procured from a pet store,
breeder, or dealer within 60 days of the onset of signs
' Protect birds from undue stress (eg, chilling or
of illness; a person has confirmed or probable psittaco-
relocation), poor husbandry, and malnutrition.
sis; or several suspect avian cases have been identified
These problems reduce the effectiveness of treat-
from the same source. Other situations can be investi-
ment and promote the development of secondary
gated at the discretion of the appropriate local or state
infections with other bacteria or yeast.
public health department or animal health authorities.
Vet Med Today: Public Veterinary Medicine
0215PVM revised.qxp 1/27/2005 11:28 AM Page 536
Investigations involving recently purchased birds
revised taxonomy of the family Chlamydiaceae, including a new
should include a visit to the site where the infected
genus and five new species, and standards for the identification of
bird is located and identification of the location where
organisms. Int J Syst Bacteriol 1999;49:415–440.
2. CDC. Summary of notifiable diseases, United States, 2001.
the bird was originally procured (eg, pet shop, dealer,
MMWR Morb Mortal Wkly Rep 2003;50:1–108.
breeder, or quarantine station). Authorities should
3. Hughes C, Maharg P, Rosario P, et al. Possible nosocomial
document the number and types of birds involved, the
transmission of psittacosis. Infect Control Hosp Epidemiol 1997;18:
health status of potentially affected persons and birds,
locations of facilities where birds were housed, relevant
4. CDC. Case definitions for infectious conditions under pub-
ventilation-related factors, and any treatment protocol.
lic health surveillance. MMWR Morb Mortal Wkly Rep 1997;46:27.
5. CDC. Division of Public Health Surveillance and
Suspect birds should be tested as recommended
Informatics. Available at: www.cdc.gov/epo/dphsi/casedef/psittacos-
(Appendix 1). Examination of sales records for other
siscurrent.htm. Accessed Dec 7, 2004.
birds that had contact with the infected bird may be
6. Schlossberg D. Chlamydia psittaci (psittacosis). In: Mandell
considered. To help identify multistate outbreaks of
GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett’s princi-C psittaci infection, local and state authorities should
ples and practice of infectious diseases. 5th ed. New York: Churchill
report suspected outbreaks to the Respiratory Diseases
7. Fudge AM. Avian chlamydiosis. In: Rosskopf WJ Jr,
Branch, Division of Bacterial and Mycotic Diseases,
Woerpel RW, eds. Diseases of cage and aviary birds. Baltimore: The
National Center for Infectious Diseases, CDC (tele-
Williams & Wilkins Co, 1996;572–585.
8. Flammer K, Trogdon MM, Papich M. Assessment of plasma
concentrations of doxycycline in budgerigars fed medicated seed and
Quarantine of birds—The appropriate animal
water. J Am Vet Med Assoc 2003;223:993–998.
and public health authorities may issue an official
9. Powers LV, Flammer K, Papich M. Preliminary investigation
quarantine for all affected and susceptible birds on
of doxycycline plasma concentration in cockatiels (Nymphicus hol-
premises where C psittaci infection has been identi-
landicus) after administration by injection or in water or feed. J Avian
fied. The purpose of imposing a quarantine is to pre-
10. Flammer K, Whitt-Smith D, Papich M. Plasma concentra-
vent further pathogen transmission. Reasonable
tions of doxycycline in selected psittacine birds when administered
options should be made available to the owners and
in water for potential treatment of Chlamydophila psittaci infection.
operators of pet stores. For example, with the
J Avian Med Surg 2001;15:276–282.
approval of state or local authorities, the owner of
11. Gylsdorff L. The treatment of chlamydiosis in psittacine
quarantined birds may choose to treat the birds in a
birds. Israel J Vet Med 1987;43:11–19.
separate quarantine area to prevent exposure to the
12. Flammer K, Aucoin DP, Whitt DA, et al. Potential use of
long-acting injectable oxytetracycline for treatment of chlamydiosis
public and other birds; sell the birds if they have com-
in Goffin’s cockatoos. Avian Dis 1990;34:228–234.
pleted at least 7 days of treatment, provided that the
13. Arnstein P, Eddie B, Meyer KF, et al. Control of psittacosis
new owner agrees in writing to continue the quaran-
by group chemotherapy of infected parrots. Am J Vet Res 1968;11:
tine and treatment and is informed of the disease haz-
ards; or euthanatize the infected birds. After comple-
14. Landgraf WW, Ross PF, Cassidy DR, et al. Concentration of
tion of the treatment or removal of the birds, a quar-
chlortetracycline in the blood of Yellow-Crowned Amazon parrotsfed medicated pelleted feeds. Avian Dis 1982;26:14–17.
antine can be lifted when the infected premises are
15. Flammer K, Cassidy DR, Landgraf WW, et al. Blood con-
thoroughly cleaned and disinfected. The area can
centrations of chlortetracycline in macaws fed medicated pelleted
feed. Avian Dis 1989;33:199–203.
16. Arnstein P, Buchanan WG, Eddie B, et al. Chlortetracycline
Bird importation regulations—Large-scale com-
chemotherapy for nectar-feeding birds. J Am Vet Med Assoc 1969;154:
mercial importation of psittacine birds from foreign
countries ended in 1993 with the implementation of the
17. Model Aviary Program (MAP). Available at: www.modelav-
Wild Bird Conservation Act.19 Limited importation of
iculture.org/. Accessed Oct 13, 2004.
personal pets and avicultural specimens is permitted at
18. National Institute of Occupational Safety and Health. Safety
and health topics, respirators. Available at: www.cdc.gov/niosh/
this time. Illegally imported (smuggled) birds are a rare
npptl/topics/respirators/. Accessed Oct 13, 2004.
but potential source of new avian chlamydiosis infec-
19. Wild Bird Conservation Act of 1992, Title I of PL 102–440.
tion to domestic flocks and should be avoided. The
16 US Code 4901–4916. Available at: http://international.fws.gov/per-
Veterinary Services of the Animal and Plant Health
mits/web%20list%20wbca.htm. Accessed Oct 13, 2004.
Inspection Service, USDA, still regulates the legal
20. Animal and Plant Health Inspection Service, USDA. 9 CFR
importation of pet birds to ensure that exotic poultry
Part 93. Importation of certain animals, birds, and poultry, and cer-tain animal, bird, and poultry products; requirements for means of
diseases are not introduced into the United States.20
conveyance and shipping containers. Subpart A—birds. Code of
These regulations are set forth in the Code of Federal
Regulations, Title 9, Chapter 1. Current minimumtreatment protocols under these regulations are not
always sufficient to cure avian chlamydiosis in all birds.
1. Eidson M. Zoonosis Update. Psittacosis/avian chlamydiosis. J Am Vet Med Assoc 2002;221:1710–1712.
Pfizer Laboratories, London, England.
2. Flammer K. Chlamydia. In: Altman RB, Clubb SL,
Dorrestein GM, et al, eds. Avian medicine and surgery. Philadelphia:WB Saunders Co, 1997;364–379.
3. Fudge AM. A review of methods to detect ChlamydiaReferences psittaci in avian patients. J Avian Med Surg 1997;11:153–165.
1. Everett KDE, Bush RM, Andersen AA. Emended description
4. Messmer TO, Skelton SK, Moroney JF, et al. Application of a
of the order Chlamydiales, proposal of Parachlamydiaceae fam nov
nested, multiplex PCR to psittacosis outbreaks. J Clin Microbiol 1997;35:
and Simkaniaceae fam nov, each containing one monotypic genus,
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0215PVM revised.qxp 1/27/2005 11:28 AM Page 537
5. Schaffner W. Birds of a feather—do they flock together?
MS, DABVP (Association of Avian Veterinarians); Mark Starr,
Infect Control Hosp Epidemiol 1997;18:162–164.
DVM, MPVM, DACVPM (AVMA Council on Public Health andRegulatory Veterinary Medicine).
From the National Association of State Public Health Veterinarians
Endorsed by the AVMA, the Council of State and Territorial
(NASPHV) Psittacosis Compendium Committee.
Epidemiologists, and the Association of Avian Veterinarians.
Consultants to the Committee: Lauri A. Hicks, DO (CDC); Keven
Address correspondence to Kathleen A. Smith, DVM, MPH, Ohio
Flammer, DVM, DABVP (Association of Avian Veterinarians);
Department of Health, 900 Freeway Dr, Columbus, Ohio 43229.
Susan E. Lance, DVM, PhD (Council of State and Territorial
Copies also can be accessed at the AVMA Web site at www.
Epidemiologists); Branson W. Ritchie, DVM, PhD, DABVP
avma.org. Browse the resources tab or search on Psittacosis
(Association of Avian Veterinarians); Thomas N. Tully Jr, DVM,
Vet Med Today: Public Veterinary Medicine
0215PVM revised.qxp 1/27/2005 11:28 AM Page 538
Appendix 1 Methods for diagnosing avian chlamydiosis.
Bacteria are classified as Chlamydophila psittaci on the basis of shared biochemical characteristics and genome composition. The individ-
ual chlamydial organisms that meet these classification criteria are not identical and represent life forms that have evolved, and continue toevolve, through infection of both ancient and naïve hosts. Diversity in the organism, the level of exposure, and the host response may cause aber-rant test results in some individual animals.
Diagnosis of avian chlamydiosis can be difficult, especially in the absence of clinical signs. A single testing method might not be adequate.
Therefore, use of a combination of culture, antibody-detection, and antigen-detection methods is recommended, particularly when only 1 bird istested. Although there is no epidemiologic evidence of increased risk to young, elderly, or immunocompromised humans, more rigorous testingshould be considered for birds in contact with these individuals. Consultation with an experienced avian veterinarian may help when selectingtests and interpreting results. Proper sample collection techniques and handling are critical for obtaining accurate test results.
Pathologic diagnosis—In birds that have avian chlamydiosis, cloudy air sacs and enlargement of the liver and spleen usually are observed
but no specific gross lesion is pathognomonic. Chromatic or immunologic staining of tissue or impression smears can be used to identify organ-isms in necropsy and biopsy specimens.
Bacteriologic culture—Use of culture is recommended to avoid limitations associated with other tests. Tissue specimens from the liver and
spleen are the preferred necropsy specimens. In live birds, combined choanal and cloacal swab specimens or liver biopsy specimens are idealfor diagnosis. Live birds being screened for C psittaci might not shed the microorganism daily. Therefore, to optimize recovery, serial specimensshould be collected for 3 to 5 consecutive days and pooled before bacteriologic culture.
Chlamydophila spp are obligate intracellular bacteria that must be isolated in tissue culture or chick embryos. Specialized laboratory facili-
ties and training are necessary for reliable identification of chlamydial isolates and adequate protection of microbiologists. The diagnostic labo-ratory should be contacted for specific procedures required for collection and submission of specimens. The proper handling of specimens iscritical for maintaining the viability of organisms for culture, and a special transport medium is required. Following collection, specimens shouldbe refrigerated and sent to the laboratory packed in ice but not frozen.
Tests for antibodies—A positive serologic test result is evidence that the bird was infected by Chlamydiaceae at some point, but it might not
indicate that the bird has an active infection. False-negative results can occur in birds that have acute infection when samples are collectedbefore seroconversion. Treatment with an antimicrobial agent can diminish the antibody response.
When samples are obtained from a single bird, serologic testing is most useful when signs of disease and the history of the flock or aviary
are considered and serologic results are compared with WBC counts and serum activities of liver enzymes. A greater than 4-fold increase in thetiter of paired samples or a combination of a titer and antigen identification is needed to confirm a diagnosis of avian chlamydiosis.
• Complement fixation (CF)—Direct CF is more sensitive than agglutination methods. False-negative results are possible in specimens from
parakeets, young African gray parrots, and lovebirds. High titers can persist after treatment and complicate interpretation of subsequent tests. Modified-direct CF is more sensitive than direct CF.
• Elementary-body agglutination—The elementary body is the infectious form of C psittaci. Elementary-body agglutination is commercially
available and detects IgM antibodies, an indicator of early infection. Titers > 10 in budgerigars, cockatiels, and lovebirds and titers > 20 in larg-er birds are frequently detected in cases of recent infection. However, increased titers can persist after treatment is completed.
Tests for antigen—Tests for antigen detect the organism. These tests give rapid results and do not require live, viable organisms; however,
false-positive results from cross-reacting antigens can occur. False-negative results can occur if there is insufficient antigen or if shedding isintermittent. As with all nonculture tests, the results must be evaluated in conjunction with clinical findings.
• ELISA—ELISA tests (eg, QuickView) were originally developed for identification of Chlamydia trachomatis in humans. The exact sensitivity
and specificity of these tests for identifying other Chlamydiaceae are not known. They are now used to identify suspected C psittaci in birds. If abird has a positive ELISA result but is healthy, the veterinarian should attempt to verify that the bird is shedding antigen via isolation of the organ-ism. When a clinically ill bird has a negative ELISA result, a diagnosis of avian chlamydiosis cannot be excluded without further testing (eg, cul-ture, serologic testing, or polymerase chain reaction [PCR] assay).
• Immunofluorescent antibody tests—Monoclonal or polyclonal antibodies, fluorescein-staining techniques, and fluorescent microscopy are
used to identify the organism in impression smears or other specimens. These tests have similar advantages and disadvantages to ELISA.
• PCR assays—Numerous laboratories offer diagnostic testing using PCR technology; PCR amplification promises to be sensitive and specif-
ic for detection of target DNA sequences in collected specimens (eg, choanal and cloacal swab specimens and blood). Results differ betweenlaboratories because there are no standardized PCR primers and laboratory techniques and sample handling vary.
Additional tests—Additional diagnostic techniques, such as rapid immunomigration, are in use or under development. Readers are encour-
aged to research peer-reviewed reports on such tests before use.
Laboratories that test avian specimens for C psittaci—Certain state diagnostic laboratories and veterinary colleges perform routine chlamy-
dial diagnostic tests. Other sources might be available. Inclusion in this list does not imply endorsement by the National Association of StatePublic Health Veterinarians or constituent institutions.
Laboratories that test avian specimens for Chlamydiaceae
Diagnostic Center for Population and Animal Health,
Michigan State University, East Lansing, Mich
Avian and Exotic Animal Clin Path Labs, Wilmington, Ohio
California Avian Laboratory, El Dorado Hills, Calif
Comparative Pathology Laboratory, University of Miami School
Infectious Diseases Laboratory (IDL), University of Georgia
College of Veterinary Medicine, Athens, Ga
Research Associates Laboratory, Dallas, Tex
Veterinary Medical Diagnostic Laboratory (VMDL),
*Specimens forwarded to another laboratory. CF = Complement fixation. EBA = Elementary-body agglutination. ELISA = Enzyme-linked immunosorbent assay. IFA = Immunofluorescent anti-
body. PCR = Polymerase chain reaction assay. RIM = Rapid immunomigration.
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Appendix 2 Treatment options for pet birds with avian chlamydiosis.
Treatment of avian chlamydiosis can be difficult, and fatalities may occur. Although treatment protocols are usually successful, knowledge
is evolving and no protocol ensures safe treatment or complete elimination of infection. Therefore, treatment for avian chlamydiosis should besupervised by a licensed veterinarian after consultation with an experienced avian veterinarian. During treatment, suggestions in the section“Treatment and care for infected birds” should be followed. All birds with avian chlamydiosis should be treated for 45 days, except as noted inthe following sections. Sources of dietary calcium (eg, cuttle bone, mineral block, oyster shell, and highly supplemented pellets) should bereduced if tetracycline drugs are orally administered. In hand-fed neonates in which dietary calcium is required, the calcium and tetracyclineshould be given at least 4 to 6 hours apart.
Treatment Using DoxycyclineDoxycycline is presently the drug of choice for treating birds with avian chlamydiosis. It is better absorbed and more slowly eliminated than
other tetracyclines. This allows doxycycline to be effective with lower drug doses (improving palatability with food or water-based administra-tion) or administered less frequently (improving ease of treatment). Treated birds should be monitored for signs of doxycycline toxicosis. Toxicosiscan cause general signs of illness (signs of depression, inactivity, and decreased appetite), green- or yellow-stained urine, and altered results ofhepatic tests (high serum activities of aspartate aminotransferase and lactate dehydrogenase and high serum concentration of bile acids). If tox-icosis occurs, administration should be stopped and supportive care provided until the bird recovers. Treatment with a different regimen or lowerdoxycycline dose can be started at a later date.
• Doxycycline medicated feed for budgerigars—The following medicated diet8 can be used to treat budgerigars with avian chlamydiosis:• Mix 1 part cracked steel oats with 3 parts hulled millet (measured by volume). Add 5 to 6 mL of sunflower oil/kg of the oat-seed mixture,
and mix thoroughly to coat all seeds. Add 300 mg of doxycycline hyclate (from capsules)/kg of oat-seed-oil, and mix thoroughly to ensure thatoats and seeds are evenly coated. Mix fresh medicated oat-seed mix daily. Feed as the sole diet for 30 days. The oats and hulled millet seed areavailable at health food stores. Small-sized millet should be selected. Sunflower oil is available in grocery stores. Doxycycline hyclate capsulesare available in 50- and 100-mg sizes.
• Doxycycline medicated water—Results of pharmacologic studies indicate that doses of 200 to 400 mg of doxycycline hyclate/L of water
for cockatiels, 400 to 600 mg/L for Goffin’s cockatoos, and 800 mg/L for African gray parrots will maintain therapeutic concentrations.9,10 Researchdata are lacking for other species, but empiric use of 400 mg/L of water has been successful for many psittacine birds. Medicated water failedto maintain therapeutic concentrations in budgerigars.8
• Orally administered doxycycline—Doxycycline is the drug of choice for oral administration; either the monohydrate or calcium-syrup for-
mulations can be used. Dosage recommendations are as follows: 40 to 50 mg/kg every 24 hours for cockatiels, Senegal parrots, and blue-front-ed and orange-winged Amazon parrots; and 25 mg/kg every 24 hours for African gray parrots, Goffin’s cockatoos, blue and gold macaws, andgreen-winged macaws. Precise dosages cannot be extrapolated for other species; however, 25 to 30 mg/kg every 24 hours is the recommendedstarting dosage for cockatoos and macaws, and 25 to 50 mg/kg every 24 hours is recommended for other psittacine species. If the bird regurgi-tates or refuses the drug, another treatment method should be used.
• Injectable doxycycline—Intramuscular injection into the pectoral muscle is often the easiest method of treatment, but not all injectable
doxycycline formulations11 are suitable for IM injection. All available formulations can cause irritation at the injection site. Vibramycin SF I.V. for-mulationa is available in Europe and is effective if administered at doses of 75 to 100 mg/kg, IM, every 5 to 7 days for the first 4 weeks and sub-sequently every 5 days for the duration of treatment. The injectable hyclate formulation labeled for IV use in humans can be used IV in birds. Thisformulation is not suitable for IM use because severe tissue reactions will occur at the site of injection.
Injectable OxytetracyclineLimited information exists for the use of the injectable, long-acting oxytetracycline product, LA-200.b. Current dosage recommendations are
as follows: SC injection of 75 mg/kg every 3 days in Goffin’s cockatoos,12 blue-fronted and orange-winged Amazon parrots, and blue and goldmacaws. This dosage might be suitable for other species but has not been tested. This product causes irritation at the site of injection and is bestused to initiate treatment in ill birds or those that are reluctant to eat. After stabilization with oxytetracycline treatment, the birds should receiveanother form of treatment to reduce the muscle irritation that is caused by repeated oxytetracycline injection.
Chlortetracycline (CTC) Medicated FeedChlortetracycline medicated feed should be the only food provided to the birds during the entire treatment. Birds’ acceptance of medicat-
ed feed is variable. Thus, food consumption should be monitored. Acceptance can be enhanced by first adapting the birds to a similar, nonmed-icated diet. Treatment begins when the birds accept the medicated feed as the sole food in their diet. The following options are available:
• Medicated mash diets (ie, > 1% CTC with < 0.7% calcium) prepared with corn, rice, and hen’s scratch.13• Pellets and extruded products containing 1% CTC can be used. They are available and appropriate for use with pet birds. Select a pellet
size appropriate for the size of bird being treated.14,15
• A special diet might be necessary for lories and lorikeets, which feed on nectar and fruit in the wild.16Experimental MethodsTreatment protocols that use late-generation macrolides and pharmacist-compounded injectable doxycycline are under investigation.
Information about these treatment protocols might be available in the scientific literature or from avian veterinary specialists.
Sources of MedicationsSources (Table 2) are not listed as an endorsement of the companies or products. Other sources might be available. Contact Product Telephone
Doxycycline hyclate capsules 50 & 100 mgDoxycycline calcium oral suspensionDoxycycline monohydrate oral suspension
Veterinary Medicine, Utrecht, Netherlands
Fort Dodge Animal Health, Fort Dodge, Iowa
Aureomycin soluble powder concentrate, 64 gm/25.6 oz
*Investigational New Animal Drug Application (INADA) is no longer required, contact the FDA at (301) 594-0796 about obtaining a personal
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