Chlamydiae in free-ranging and captive frogs in Switzerland

Area of Science:

• Veterinary Microbiology
• Amphibian Pathology
• Molecular Diagnostics

Background:

• Chlamydiae are known bacterial pathogens affecting various animal species.
• Previous studies have not extensively investigated Chlamydia prevalence in Swiss amphibian populations.
• Understanding Chlamydia in frogs is crucial for amphibian health and disease surveillance.

Purpose of the Study:

• To retrospectively investigate Chlamydia involvement in a Swiss frog mass mortality event (1991/1992).
• To determine the prevalence of Chlamydia in a free-ranging Swiss amphibian population (Rana temporaria).
• To identify Chlamydia species present in examined frog samples.

Main Methods:

• Histopathology and immunohistochemistry using a monoclonal antibody against chlamydial lipopolysaccharide.
• 16S rRNA polymerase chain reaction (PCR) followed by DNA sequencing on formalin-fixed, paraffin-embedded tissues.
• Analysis of samples from a mass mortality event, routine postmortem investigations, a control group, and a prevalence study.

Main Results:

• Chlamydia suis S45 was detected in 14.8% of frog samples from the 1991/1992 mass mortality event.
• Prevalence study found 2.5% of Rana temporaria positive for various Chlamydia species, including C. suis S45, Chlamydophila pneumoniae TW-183, and Chlamydophila abortus S26/3.
• Chlamydophila pneumoniae TW-183 was also identified in exotic zoo frogs; C. suis S45 and C. abortus S26/3 were detected in frogs for the first time.

Conclusions:

• Chlamydia species are present in Swiss frogs, but no causal link was established with the 1991/1992 mass mortality.
• The study identified C. suis S45 and C. abortus S26/3 in frog material for the first time.
• Further research is needed to understand the pathogenicity and impact of Chlamydia in amphibians.