Coccidioidomycosis

Description

Coccidioidomycosis or "Valley fever" is a disease caused by the fungus Coccidioides immitis, found in the soil of endemic areas. The disease is acquired by inhalation of fungal spores from dust, usually generated by human activities or natural disasters. The incubation period ranges from 7 to 21 days. Most infections (60%) are asymptomatic. People who have symptoms usually develop a self-limited "flu-like illness" characterized by fever, headache, rash, muscle aches, dry cough, weight loss, and malaise. In rare instances, people can develop severe lung disease (for example, cavitary pneumonia) or dissemination to the central nervous system (for example, meninges), joints, bones, and skin. People at increased risk for severe pulmonary disease are the elderly and those with chronic medical conditions such as congestive heart failure, diabetes, chronic obstructive pulmonary disease, cancer, and corticosteroid use. People at increased risk for disease dissemination include African-Americans and Filipinos, those with immune compromising conditions (i.e. HIV), and pregnant women. Diagnosis is usually made using serologic tests or culture of direct specimens. Coccidioidomycosis is not transmitted from person to person.

Occurrence

C. immitis is endemic in regions in the Americas with an arid climate, yearly rainfall of 5 to 20 inches, hot summers, winters with few freezes, and alkaline soils. In the United States, it is found in Arizona, Southern California, New Mexico, Western Texas, and parts of Utah. Outside the United States, coccidioidomycosis is endemic in parts of Argentina, Brazil, Colombia, Guatemala, Honduras, Mexico, Nicaragua, Paraguay, and Venezuela.

Risk to Travelers

In endemic areas, people participating in, or present during, ground disturbing activities resulting in exposure to dust can be at increased risk for disease. These outdoor activities include: construction, landscaping, mining, agriculture, archaeological excavation, military maneuvers, and recreational pursuits (for example, dirt biking). Natural events that result in generation of dust clouds in endemic areas, such as earthquakes or wind storms, increase the risk of infection among exposed people. Once infected with C. immitis, a person is immune to reinfection.

Treatment

The majority of people with acute symptomatic coccidioidomycosis do not require treatment because the illness is self-limited. People at increased risk for dissemination may need to receive antifungal therapy when diagnosed with acute coccidioidomycosis. All people with disseminated disease should receive antifungal treatment. Fluconazole, which can be given orally, is generally the treatment of choice; however, those who have diffuse pneumonia or who are pregnant should be given Amphotericin B, an intravenous drug. Recommended duration of therapy varies, from 3 to 6 months in those with uncomplicated respiratory infection, to prolonged, sometimes life-long, treatment in those with meningitis.

Preventive Measures

Although complete prevention of infection is not possible, people, especially those at increased risk for severe and disseminated disease, can decrease their risk by limiting their exposure to outdoor dust in endemic areas. Dust-control methods include wetting soils before disturbing the earth or using outdoor vehicles with enclosed air-conditioned cabs. People should also be advised to avoid transporting fomites contaminated with soil (for example, cotton or straw) from endemic areas because infections have been reported among people who had never visited the endemic areas but were exposed to such fomites. Wearing well-fitted dust masks capable of filtering particles as small as 0.4 µm can provide added protection in those at high risk for exposure to dust from endemic areas, or those at high risk for severe or disseminated disease. No effective vaccine for coccidioidomycosis is currently available.

© Center for Disease Control

Credits: National Center for Infectious Diseases