Coccidioidomycosis
Description
Coccidioidomycosis or “Valley fever” is
a disease caused by the fungus Coccidioides immitis, found
in the soil of disease-endemic areas. The disease is acquired by
inhalation of fungal spores from dust, usually generated by human
activities or natural disasters.
Occurrence
C. immitis is endemic in regions in the Americas
with an arid climate, yearly rainfall 5–20 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 for Travelers
In disease-endemic areas, persons can be at increased
risk for disease if they participate in or are present during ground-disturbing
activities resulting in exposure to dust. These outdoor activities
include construction, landscaping, mining, agriculture, archaeologic
excavation, military maneuvers, and recreational pursuits (e.g.,
dirt biking). Natural events that result in generation of dust clouds
in disease-endemic areas, such as earthquakes or windstorms, increase
the risk of infection among exposed persons.
Clinical Presentation
The incubation period ranges from 7 to 21 days. Most
infections (60%) are asymptomatic. Persons who have symptoms usually
have a self-limited influenzalike illness characterized by fever,
headache, rash, muscle aches, dry cough, weight loss, and malaise.
In rare instances, severe lung disease (e.g., cavitary pneumonia)
or dissemination to the central nervous system (e.g., meninges),
joints, bones, and skin may develop. Persons 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. Persons at increased
risk for disseminated disease include African-Americans and Filipinos,
those with immunocompromising conditions (e.g., HIV), and pregnant
women. Diagnosis is usually made by serologic tests or culture of
direct specimens. Coccidioidomycosis is not transmitted from person
to person. Once infected with C. immitis, a person is immune
to reinfection.
Prevention
Although complete prevention of infection is not
possible, persons, especially those at increased risk for severe
and disseminated disease, can decrease their risk by limiting their
exposure to outdoor dust in disease-endemic areas. Dust-control measures
include wetting soil before disturbing the earth or using outdoor
vehicles with enclosed, air-conditioned cabs. Persons should also
be advised to avoid transporting items contaminated with soil (e.g.,
cotton or straw) from disease-endemic areas because infections have
been reported among persons who had never visited the 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
for those at high risk for exposure to dust from disease-endemic
areas or those at high risk for severe or disseminated disease. No
effective vaccine for coccidioidomycosis is currently available.
Treatment
Most persons with acute symptomatic coccidioidomycosis
do not require treatment because the illness is self-limited. Persons
at increased risk for dissemination may need to receive antifungal
therapy when diagnosed with acute coccidioidomycosis. All persons
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 lifelong, treatment
in those with meningitis. An infectious diseases specialist should
manage these patients.
— Rana
Hajjeh, Anil Panackal, David Warnock
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