Pathophysiology in mountain yellow-legged frogs (Rana muscosa) during a chytridiomycosis outbreak

Area of Science:

• Amphibian biology
• Infectious diseases
• Ecology

Background:

• Chytridiomycosis, caused by the fungus *Batrachochytrium dendrobatidis*, is a major driver of amphibian declines worldwide.
• The fungal pathogen infects amphibian skin, leading to disease and mortality.
• While laboratory studies offer insights, the pathophysiology of chytridiomycosis in wild populations remains incompletely understood.

Purpose of the Study:

• To investigate the pathophysiology of chytridiomycosis in a wild amphibian population.
• To determine if disease development in wild frogs aligns with laboratory findings.
• To assess the relationship between pathogen load and physiological disruptions in affected amphibians.

Main Methods:

• Blood biochemistry measurements were collected from mountain yellow-legged frogs (*Rana muscosa*) during a natural disease outbreak.
• Pathogen load of *Batrachochytrium dendrobatidis* was assessed in conjunction with physiological data.
• Analysis focused on fluid and electrolyte balance and acid-base balance.

Main Results:

• Higher pathogen loads were significantly associated with disruptions in fluid and electrolyte balance in wild frogs.
• No significant association was found between pathogen load and fluctuations in acid-base balance.
• Disease development in wild *Rana muscosa* is consistent with findings from laboratory studies.

Conclusions:

• Pathogen load in chytridiomycosis directly impacts amphibian fluid and electrolyte homeostasis.
• The pathophysiology of chytridiomycosis is conserved across species and environments (laboratory vs. wild).
• Understanding disease mechanisms is crucial for developing effective amphibian conservation and mitigation strategies.