Compendium of Psittacosis (Chlamydiosis) Control, 1999 provided by the American Veterinary Medical Association (AVMA)
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 non-respiratory 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 (e.g., 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, non-psittacine 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 (e.g., 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 unapparent 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 (i.e., 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 another 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 itís in vivo efficacy has not been determined, erythromycin probably is the best alternative agent for humans for whom tetracycline is contraindicated (e.g., 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 (e.g., 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 non-standardized 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 (e.g., 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 (e.g., 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 re-rinse it to remove disinfectant. Discard items that cannot be adequately disinfected (e.g., 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 (e.g., Roccal, Zephiran) is effective, as is 70% isopropyl alcohol, 1% Lysol, 1:100 dilution (i.e., 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 (i.e., 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 (e.g., 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 (i.e., 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 (e.g., 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 (e.g., 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 (e.g., 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, non-medicated 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 (i.e., 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 speciesí. 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. [-] NOAH | Member Center | Care for Pets | Professional Resources NetVet & Electronic Zoo | Network News | AVMA Home [-] [The AVMA Network] Copyright © 1998 American Veterinary Medical Association