Chlamydial infections in free-ranging raptors presenting to a university veterinary medical teaching hospital (1993-2022).

OBJECTIVE

To describe the prevalence, clinical findings, lesions, and risk factors associated with chlamydial infections in free-ranging raptors presented to a university veterinary medical teaching hospital.

METHODS

Medical records retrospectively searched for raptors admitted from January 1993 through April 2022 were tested for Chlamydia spp infections using quantitative PCR (qPCR), immunohistochemistry, culture, and sequencing. Findings were collected and analyzed. Multivariable logistic regression analyzed the association between Chlamydia spp infection status and risk factors, including age class, species, sex, and season of admission.

RESULTS

The prevalence for cases that tested positive for Chlamydia spp on 1 or more diagnostic tests, including mucosal qPCR samples for Chlamydia spp, tissue PCR for C buteonis, and mucosal qPCR genotyped as C buteonis, was 1.9% (74 of 3,983). All positive cases were from the genus Buteo (n = 74). Juvenile birds and winter season had higher odds of infection. All birds were in poor body condition (n = 74), often with moderate-to-severe CBC and biochemistry abnormalities consistent with multiorgan chronic inflammatory disease, emaciation, and dehydration. On postmortem examination of Chlamydia-positive birds (58 of 74), hepatitis (44 of 56), nephritis (24 of 39), splenitis (22 of 53), airsacculitis (21 of 43), myocarditis (21 of 39), and pneumonia (21 of 38) were common lesions, with intracellular bacteria in multiple tissues.

CONCLUSIONS

Signalment, season of admission, clinical signs, clinicopathologic findings, and Chlamydia-specific testing identified chlamydial infections in free-ranging raptors. Appropriate protections to prevent potential zoonotic transmission in clinical wildlife rehabilitation settings are recommended.

CLINICAL RELEVANCE: Many clinical parameters used to identify C psittaci infection in parrots can also be used to identify chlamydial infections in raptors.