Avian Psittacosis: Two Case Reports
By Sarah Levine, VMD 

Psittacosis, infection with Chlamydophila psittaci, is a common world wide problem for many captive and wild birds.  It is most commonly seen in psittacine birds (especially cockatiels and parakeets), doves and pigeons but has been confirmed in 100 bird species⁽¹⁾.  Israeli veterinarian, Limor Miara, is all too familiar with the disease.  Her practice sees a large volume of avian patients and she diagnoses psittacosis regularly.  Some of her patients present for routine exams and others due to illness.

A  2-year-old, male, green, black-tailed conure arrived to Dr. Miara for a general “well-visit”.  Physical exam revealed a healthy bird.  She ran a chlamydophila IFA test to be sure the bird was not an asymptomatic carrier of this potentially zoonotic disease.  The test results were positive.  The bird was then treated with an injectable doxycycline (100mg/kg) once weekly for 6 weeks.  After a 2-week rest period he was rechecked and tested negative for Chlamydophila psittaci.

A 4-year-old, male, Jacko Kongo, who had recently been released from quarantine after importation into Israel, presented to Dr. Miara after a 2-day history of decreased appetite and diarrhea.  He had been tested while in quarantine for Newcastle disease and avian influenza (both of which were negative) and had been given doxycycline for 45 days.  Examination showed a thin (522gm), aggressive bird suffering from diarrhea. 

Dr. Miara’s differential diagnosis list included psittacosis, colitis, candida of the digestive tract, etc.  Diagnostic tests that were run included: PCR test for C. psittaci, microscopic examination of slides of diarrhea (with and without staining), bacteriology and mycology cultures.  Bacteriology and mycology tests were negative.  No coccidia were seen in the stool, however, there was a possibility of candida.  The C. psittaci PCR test was positive.  The bird was treated with nystatin per os (2ml /100ml drinking water) and baytril 10 % per os (0.2ml/100 ml drinking water).  He was force fed and placed under a heat lamp until his condition improved (which took 3 days). He also received injectable doxycycline (100mg/kg) once weekly for 6 weeks.  Two weeks post-cessation of treatment he tested negative for C. psittaci.  

Epidemiology:
C. psittaci is excreted in the feces and nasal discharges of infected birds. The organism may stay infectious in dried feces for several months⁽¹⁾. Not all infected birds show clinical signs; nevertheless, they can shed the organism intermittently.  Shedding can be activated by stress factors such as shipping, crowding, chilling, breeding, etc⁽²⁾.  Incubation period ranges from 3 days to several weeks.  In latent infections, however, active disease can appear years after infection⁽³⁾. Of course, clinical disease may be seen with no identifiable exposure.

Clinical Signs: 
Signs of avian psittacosis include lethargy, anorexia and ruffled feathers, which are all clinical signs common to any systemic illness.  Other signs include rhinitis, ocular or nasal discharge, diarrhea, excretion of yellow-green urates (indicative of liver disease), dyspnea, conjunctivitis, weight loss, and acute death. Whether a bird shows acute or chronic signs of illness depends on the species of bird, virulence of the strain, infectious dose, stress factors, age, type of treatment, etc⁽²⁾. Due to its potential to cause disease in humans, psittacosis must be considered with any bird suffering from respiratory or digestive tract signs⁽¹⁾.

Some data suggests that properly treated birds can clear C. psittaci and most epizootiologic studies would support this theory⁽¹⁾.  Therefore, latent infections may represent chronic untreated infections⁽¹⁾.

A series of tests is often necessary to diagnose C. psittaci.  The CBC is often helpful. Birds with active infections have a severe leukocytosis, heterophila (cell counts >30,000) and possibly monocytosis.  Chronically infected birds may develop basophila and anemia. Some birds (especially cockatiels) may have a normal leukogram and still be infected(4).  Chemistries may reveal elevated liver enzymes.  Radiography may show hepatomegaly, splenomegaly, air sacculitis or pneumonitis.

Diagnosis:
The Gold Standard for diagnosing C. psittaci is by identification of the organism in tissue culture⁽⁴⁾.  However, testing takes several weeks, requires a specialized laboratory, is expensive, and a negative culture does not rule out psittacosis (perhaps the sample was insufficient, the organism died in transit, the organism did not grow in the test media, etc.).  All these reasons make tissue culture an impractical diagnostic test for day-to-day use.

A combination of serologic tests (ELISA antibody titers, complement fixation, elementary body agglutination, IFA) and attempts to isolate the organism in samples (ELISA, PCR, culture) from the choana or cloaca provide the most accurate diagnosis in clinically ill birds⁽¹⁾. No single diagnostic test can provide a 100% guarantee that a bird is not infected by C. psittaci. A combination of tests is required to determine the C. psittaci status of a bird. 

Serology is best for determining if birds have previously been infected, to confirm an active infection (when a 4-fold rise in titer is seen in paired samples), or to support the likelihood of infection when an assay to detect the presence of the organism is negative. Serology, therefore, provides an advantage for detecting latently infected birds that appear healthy but do not persistently shed organisms⁽¹⁾.  Some breeders use serology to screen chicks prior to them leaving the aviary.  They can thereby prove that they sell only C. psittaci negative chicks⁽⁵⁾.

Treatment and Prevention:  
C. psittaci infection responds quickly to treatment with tetracyclines.  Doxycycline is currently the treatment of choice and is maintained for a minimum of 45 days.  Birds undergoing treatment should be kept in isolation from other birds in an easy to disinfect cage.  Thorough cleaning and disinfection of the contaminated environment should be done to eliminate infectious dust and thereby reduce the chance of reinfection. Handlers should wear protective clothing when handling infected birds or cleaning cages⁽³⁾. It is important to remember that a bird that recovers from chlamydiosis is susceptible to reinfection⁽¹⁾.  A follow-up examination after treatment is necessary to insure successful therapy was achieved⁽⁴⁾.

References:
1.   Ritchie Branson W. Diagnosis and Prevention of Avian Chlamydiosis. Proceedings, Western Veterinary Conference, 2003.
2.   National Association of State Public Health Veterinarians (NASPHV), Compendium of Measures to Control Chlamydophila psittaci. March 2004.
3.   Iowa State University, Institute for International Cooperation in Animal Biologics, Emerging and Exotic Diseases of Animals, Chlamydiosis (Avian).
4.   Wissman Margaret A. Chlamydia and Chlamydophila. Proceedings, Western Veterinary Conference, 2003.
5.   Ritchie Branson W. Management of Common Avian Infectious Diseases.  Proceedings, Atlantic Coast Veterinary Conference, 2002.         

For any further assistance please contact us at: info@biogal.co.il   


Technical Tip: Avian Sample Collection Procedure   
Note: For better understanding please refer to the product information.  

When collecting blood, use caution to avoid sample cross contamination and/or infection to birds. Between birds you should wash hands, sanitize clippers with alcohol, and avoid touching the pre-punched disks on the filter paper where the blood is to be placed.

Label the tooth of the filter paper (with the 2 pre-punched disks) with the bird’s ID and species beforehand. This is important so that you can match the results to the proper birds.

With the bird under control, examine the toenail to insure that it is clean. A swab of alcohol can be used to clean the area if necessary. Use a clean pair of nail clippers to clip the toenail just enough to nick the vein and produce blood flow. This should be approximately 2/3 of the distance from the root of the toenail.

Remove the first bead of blood with a swab or absorbent cotton ball, then carefully place the pre-punched disks to the blood flow and absorb a few drops of blood. When blood flow is slow, squeeze gently on the toe with a pumping action. It is necessary to completely fill both disks on both sides of the filter paper. The usual amount of blood needed is 1-3 drops.

Once the sample has been collected, set the filter paper aside to dry on a clean surface. Check that the bird is no longer bleeding before returning it to its cage. To stop further bleeding, apply a coagulant such as Kwik Stop to the area. Cornstarch or flour may also be applied as alternatives.

Allow the disks to dry completely by leaving them at room temperature for 30-60 minutes. Once the disk is completely dry, it may be stored in a plastic bag or used for testing.  

In order to perform the ImmunoComb^® Avian Antibody Test for Chlamydophila psittaci , place the dry disk at the bottom of the well in row A of the developing plate one hour before beginning the test.

For more information, please contact us at info@biogal.co.il