San Joaquin Valley Fever, now called Valley Fever for short, was named because of an outbreak among farm workers in the well-known San Joaquin Valley of California. The condition is caused by inhaling dust or dirt contaminated with a fungus of the Coccidiodes genus. The fungus is inhaled into the lungs where it may simply cause a low-grade chronic cough and calcification (mineralization) of local lymph nodes or, if the immune system is weak, it can cause pneumonia or even disseminate throughout the body.
About The Fungus
- The fungus lives in many areas, including:
- Desert areas in south and central Washington
- Desert areas in central Oregon
- All desert areas in California, Utah, and Nevada
- All desert areas in Central and South America
- Favors sandy, alkaline soil with little rainfall
- Hot summers and cold winters create ideal conditions
- Fungal spores (arthroconidia) are released after rainfall
- High winds, earthquakes, and crop harvesting can stir up spores
- Infection occurs through inhalation of airborne spores
Getting Sick
- 60% of animals and people infected never show symptoms
- Infection may only be detected via blood test showing antibodies
- 40% develop symptoms 1–3 weeks after inhalation:
- Cough (dry or productive)
- Fever
- Weight loss
- Appetite loss
- If infection is limited to lungs, recovery rate is ~90% with treatment
- If the infection disseminates to other organs, it becomes more serious
- Dissemination often occurs in a specific order, appearing in certain organs first
- Not contagious—only contracted by inhaling spores from dirt
Testing
- Radiographs
- Used to assess lungs and rule out conditions like:
- Heart disease
- Tracheal collapse
- Localized pneumonia
- Findings may include enlarged lymph nodes and lung infiltration
- Used to assess lungs and rule out conditions like:
- Cytology
- Samples from tracheal wash/lavage may contain fungal spores
- Appearance of spores confirms diagnosis due to their distinctive size and shape
- Blood Testing
- Least invasive diagnostic method
- Detects antibodies using tests like:
- Tube precipitin
- Complement fixation
- Latex agglutination
- Gel immunodiffusion
- ELISA (enzyme-linked immunoassay)
- Important to distinguish past exposure from active infection
- Animals without symptoms should not be treated based only on a positive antibody test
Treatment
- Fungal infections require long-term treatment (up to a year)
- Medication continues until:
- Symptoms resolve
- Radiographs normalize
- Antibody levels stabilize (may never drop to zero)
- Common antifungal medications:
- Ketoconazole
- Itraconazole
- Fluconazole
- Liver enzymes must be monitored during treatment
- Prognosis is good if infection is confined to the lungs
- Severe cases may involve:
- Bone (amputation may be required for recovery)
- Eyes (may need enucleation for relief)
- Immunosuppressive drugs should be avoided during treatment