Diagnosis of Chlamydiosis Using DNA Probes
Alicia A. Turner; Rachel C. Robbins; Kate E. Pennick, BS; Christopher
R. Gregory, DVM, PhD; Kenneth S. Latimer, DVM, PhD
Undergraduate Research Biology Program (Turner, Robbins), The University of Georgia, Athens,
GA 30602; Department of
Pathology (Pennick, Latimer), and Department of Small Animal Medicine
(Gregory), College of Veterinary Medicine, The University of Georgia, Athens,
GA 30602
 
Psittacosis (also known as ornithosis or chlamydiosis) is caused by Chlamydophila
psittaci (previously Chlamydia psittaci), a Gram-negative
bacterium that lacks a cell wall. This organism proliferates intracellularly
and can cause disease in various species of birds including psittacine
birds, pigeons, and doves (Fig 1). Signs of disease in birds can
be acute such as diarrhea, loss of appetite, respiratory complications
or chronic such as torticollis, tremors, and convulsions. Death also
may occur. The disease is transmitted among birds by inhalation of
aerosolized fecal contents, aerolized particles produced by sneezing,
or by exposure to a bird owner’s contaminated clothing. Epornitic
transmission from bird to bird can result in flock outbreaks of disease.
Zoonotic transmission from birds to humans can result in flu-like
symptoms such as coughing, muscle aches, fever, chills, and headache.
Occasionally, death may occur. Psittacosis can be transmitted from
birds to humans by direct contact, inhalation of dried bird droppings
and feather dust, bites, mouth-to-beak contact, and handling of infected
birds’ tissues and feathers.
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| Figure
1. Elementary bodies of Chlamydophila psittaci (previously Chlamydia
psittaci) in the cytoplasm of hepatocytes (Parrot, liver,
hematoxylin and eosin stain). |
Avian chlamydophilosis (chlamydiosis) may be difficult to diagnose
if only formalin fixed tissues are submitted for evaluation. The present
study used DNA in situ hybridization to diagnose this disease
in formalin fixed, paraffin embedded tissue specimens (. This technique
provides an additional method to detect Chlamydophila psittaci in
avian tissues, particularly when the organism is difficult to identify
because of severe inflammation (Fig. 3) or lack of major initial or
elementary body formation in hematoxylin and eosin-, Machiavello-,
or Giminez-stained tissue sections.
 |
 |
| Figure
2. Chlamydophila psittaci organisms are detected
in hepatocytes and Kupffer cells by DNA in situ hybridization
(Same parrot as Figure 3, DNA probe with formazan chromagen
and fast green FCF counterstain) |
Figure
3. Necrosis of hepatocytes and heterophilic inflammation
are present in the liver of a bird with chlamydiosis. Elementary
bodies cannot be seen (Same parrot as Figure 2, hematoxylin
and eosin stain). |
Selected Reading
Tully T: Chlamydia psittaci (parrot fever) infection in companion
birds. (http://www.parrottalk.com/chlamydia.html).
What you should
know about…psittacosis. NJDHSS, Communicable
Disease Service: Psittacosis. (http://www.state.nj.us/health/cd/f_psittacosis.htm).
Wallner-Pendleton E: Psittacosis (Chlamydia psittaci infections) in
pet birds. Extension Veterinarian. (http://www.ianr.unl.edu/pubs/animaldisease/nf28.htm).
Anonymous. Appendix A methods for diagnosing avian chlamydiosis. Am
Vet Med Assoc (http://www.avma.org/pubhlth/psittappenda.asp).
Hewinson GR, Griffiths PC, Bevan BJ, Kirwan SES, Field ME, Woodward
MJ, Dawson M: Detection of Chlamydia psittaci DNA in avian clinical
samples by polymerase chain reaction. Vet Microbiol 54:155-166,
1997.
Acknowledgement
Photographs
of Archie (Blue and Gold Macaw) and Heidi (Mustache Parakeet) are by their
owner, Lisa Holthaus. |