dvm360: From Soil to Systemic Disease: Understanding and Managing Valley Fever in Veterinary Patients

Coccidioidomycosis, also known as Valley fever, is caused by the dimorphic fungi Coccidioides (Coccidioides posadasii and Coccidioides immitis), which live in the soil in dry and hot environments. In the United States, Coccidioides is most common in the southwest, specifically in Arizona and southern California, where it is considered endemic, but also as far north as Washington and as far east as Texas. Internationally, it is also seen in Mexico and parts of Central and South America.

Arthroconidia are inhaled from the environment and phagocytosed by alveolar macrophages, where they first develop into a spherule. The spherule then develops hundreds of endospores inside it, which eventually rupture, releasing the endospores. Those endospores cause local pyogranulomatous inflammation and can disseminate via lymphatics to the tracheobronchial lymph nodes and/or hematogenous throughout the rest of the body.

Dr. Chappell is a board-certified small animal internal medicine specialist at Thrive Pet Healthcare Specialists North Scottsdale in Arizona. She earned her Doctor of Veterinary Medicine degree from Midwestern University in 2019, followed by a rotating internship at The Animal Medical Center in New York City. She then completed a three-year residency in small animal internal medicine at Iowa State University in 2023 and became a diplomate of the American College of Veterinary Internal Medicine in 2024.