What is Valley Fever?

by Amanda L Maus DVM

Catalina Pet Hospital

Tucson, AZ
 

Valley Fever is the common name for the fungal disease coccidiodomycosis.  The fungus lives in the soil of the Sonoran Desert.  The disease occurs when the fungal spores are inhaled or the spores directly enter a wound. Although more common in pets who spend time outdoors, indoor only cats can also acquire Valley Fever.  The disease is not directly transmitted by a sick animal to another animal or person.  This infection has been found in humans, pets, and wildlife.  Unfortunately, there is no vaccine to prevent Valley Fever.

If the fungus is inhaled, it causes a lung infection.  At this point, some pets are able to fight off the infection with no outside intervention.  Other pets become symptomatic.  The early signs of a lung infection may include one or all of the following: lethargy/fever, decreased appetite, and coughing/wheezing.  In cats, the disease may be mistaken for asthma or other diseases.  The signs of a skin infection are an oozing wound or abscess that do not heal or do not respond to antibiotics.  If Valley Fever is not recognized or treated, the disease spreads (disseminates) to other parts of the body such as the brain, bones, and organs.  At that stage, the pet may have seizures, limping, etc. 

X-ray of a cat pelvis with Valley Fever

Valley Fever lung infections can be diagnosed with a combination of chest x-rays and blood tests for antibody levels.  Skin infections can be diagnosed with cytology or culture.  Bone infections can be diagnosed with a combination of x-rays and blood tests for antibody levels.  Other disseminated infections may need referral to a specialist for a CT, MRI, etc.

Valley Fever can be treated with a prescription for an inexpensive human medication called Fluconazole.  This medication may be given for months or years depending on the severity of the infection.  Fungal disease is much more difficult to treat than a bacterial infection.  Repeating the antibody blood tests several times per year helps your veterinarian monitor response to treatment.  Stopping the medication too early can cause the symptoms to come back.  After the antibody levels become very low or negative, pets can be tried off of the medication. However, some pets relapse when they stop the medications and other pets may become infected again.