Updated 16 October 2015


A fungal disease typically occurring in the Western United States.



A fungal disease typically occurring in the Western United States.

Alternative names

Valley Fever, San Joaquin Valley Fever.

What is it?

Usually a mild and self-limited illness, caused by a fungus found in the soil, common in certain areas, but it can become a much more serious in people with compromised immune systems, when it can cause a fatal illness if untreated.

What causes it?

Infection with a fungus, Coccidioides immitis or posadasii, which occurs in the soil in some of the South-western states of the US, including California, Texas, Nevada, Arizona, Utah and New Mexico. It is dormant during long dry periods, but it is activated after rainfall, and forms spores which are carried in the air, especially when earth is disturbed by farming or building. Inhalation of these spores leads to the infection. It isn't spread from person to person. The disease often affects people working as farmers, construction workers and archaeologists.

What are the symptoms?

This is usually a mild disease, with symptoms such as flu, coughing, fever, headache, muscle pains and rashes. It is estimated that around half the population in affected areas have experienced the infection, perhaps without recognising it.

But it can create a more serious illness in people of African, Asian or Hispanic descent, and also in pregnant women and those with a weakened immune system, such as people with HIV/AIIDS. In such susceptible people, it can be a serious and potentially fatal illness. The disease can cause severe pneumonia, lung nodules, and in the worst form in which the infection has spread widely through the body, there may be skin ulcers, abscesses in skin and bone, severe joint pains, inflammation of the heart, urinary tract infections and meningitis.

How is it diagnosed?

Characteristic cells can be seen microscopically in body fluids, such as sputum, and in biopsy samples of infected tissue. Skin testing and blood tests can also help to confirm the diagnosis.

How is it treated?

In uncomplicated minor cases, some doctors would not start treatment at all, except in specifically vulnerable patients. Antibiotics such as Fluconazole, or a similar drug, would be used, except in pregnant women, in whom Amphoteracin B is advisable. In people with more advanced and severe infections, high dose Fluconazole (or similar azole drugs ) and perhaps intravenous Amphoteracin B would be used.

What is the prognosis?

In the common mild cases in healthy people not especially susceptible to this infection, the illness can be mild and self-limiting. In people with immune deficiency, it can be very severe and even fatal, especially where there is meningitis.

When to call the doctor

When a severe chest infection arises in someone with immune deficiency.

How can it be prevented?

People at higher than average risk, such as pregnant women, diabetics, and the immune-compromised should be advised to avoid activities which increase the risk of such infections, such as construction work and archaeological digs, especially in areas where the fungus is endemic.


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