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
  • 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

Source