Coccidioidomycosis - also known as Valley Fever
Coccidioidomycosis was first described about 100 years ago in Argentina
. It presents as a flu-like disease caused by a fungus
, (Coccidioides immitis
), found in the soil in the South Western USA
, Central and South America. Once fairly rare, incidence has increased dramatically in recent times; it is commonly found in people who are exposed to soil dust. A major outbreak occurred in the San Joaquin Valley
after the building of several air bases disturbed the soil causing many airmen to become infected - hence it is often referred to as Valley fever. Earthquakes
are also responsible for isolated outbreaks.
Most infected people are either asymptomatic or have a self-limiting illness, requiring a few days or weeks off work. However, it can be much more severe, especially in people of Asian origin, African-Americans, people with diabetes, immuno-supressed individuals, pregnant women and those with AIDS.
Initially, a headache, cough, high temperature, aches and pains and possibly a rash may develop in 50% of infected individuals. In more severe cases pneumonia, meningitis, skin ulcers, bone and joint infections (synovitis) occur and chronic infection may last up to 2 years.
Development of the disease
C. immitis grows as a mold just below the surface of the soil. When conditions are right, usually in late summer when the weather is dry, arthroconidia (the infective particles) are released into the air and enter the body via the respiratory tract. Once in the lungs each particle changes shape and produces thousands of spores, each of which is capable of spreading through the lung and reproducing in the same way, resulting in acute respiratory infection after about a week.
Drug treatment using fluconazole and itraconazole is generally considered to be the most effective, as is amphotericin B, althought the latter is toxic in large doses. The search for new and more effective drugs is a high priority, but a vaccine would be the ideal choice since immunity to C. immitis is lifelong.