Introduction

• Systemic mycotic infection.
• Etiological agent: soil-borne, dimorphic fungus, Coccidioides immitis Coccidioides immitis.
• Signs of infection: cough, respiratory distress, lameness, peripheral lymphadenopathy, ocular signs, cutaneous draining tracts.
• Route of infection: inhalation.
• Diagnosis: characteristic pulmonary, skin, ocular, or orthopedic lesions.
• Identification: of organism in cytological or histopathological samples.
• Treatment: Itraconazole, ketaconazole, and other antifungal agents.
• Prognosis: Good to guarded.

Pathogenesis

Etiology

• Coccidioides immitis Coccidioides immitis.

Predisposing factors

• Young male dogs.
• Exposure to a common source outside in an endemic area.
• Outbreaks of the disease occur after rainy periods, dust storms and earthquakes.
• Increased prevalence of the disease occurs in late summer and early fall.

Pathophysiology

• The organism primarily gains entry into the body via inhalation.
• The inhaled arthroconidia convert in the lung to a yeast phase, characterized by spherule formation that undergoes division, producing endospores.
• Typically, the cell-mediated immune system clears the infection rapidly.
• In some cases, endospores are released and disseminate to the hilar lymph nodes and distant tissues eg bones, skin, eyes, heart, testicles, central nervous system, liver, spleen and/or kidneys.
• Isolated cutaneous disease may occur from contamination of wounds with the organism.

• With a normal immune system and without an overwhelming infective burden the infection is rapidly cleared via cell-mediated immune system mechanisms.
• In some cases the organism disseminates throughout the body.

Timecourse

• Incubation time is typically 1-3 weeks.
• Initial pulmonary infection may go undetected.
• Subclinical forms of the disease may persist, with clinically obvious disseminated disease occurring months to years later.

Epidemiology

• Organism present throughout the southwestern United States, Mexico, Central America and South America.

Diagnosis

Treatment

Prevention

Outcomes