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Coccidioidomycosis

Coccidioidomycosis is a topic covered in the 5-Minute Clinical Consult.

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Basics

Description

  • A pulmonary fungal infection caused by the dimorphic fungus, Coccidioides immitis, which is endemic to the southwestern deserts of the United States:
    • Transmitted through inhalation of air-borne fungal spores (arthroconidia)
    • Rarely progresses to involve extrapulmonary sites (<1%): bone, CNS, endocrine/metabolic, musculoskeletal, nervous, pulmonary, skin, and exocrine systems
    • Incubation period is 1 to 4 weeks after exposure.
    • Pulmonary infection most common clinical manifestation; most commonly subacute; more than half of infections are subclinical (1).
  • Synonym(s): desert rheumatism; cocci; valley fever

Epidemiology

Affects patients of all ages, with no gender predilection

Incidence
  • In the United States: 150,000 cases estimated per year (0.5% extrapulmonary); only about 10,000 cases are actually reported. Overall incidence is rising; 73% increase in African Americans, who also have a higher rate of invasive disease than Caucasians (2)
  • Endemic in
    • Southern Arizona
    • Southern and Central California
    • Southwestern New Mexico, West Texas
    • Parts of Mexico, Central and South America
  • Increased construction activities, such as home-building, especially in the southwestern United States, has likely resulted in increased aerosolization of fungal spores from soil, leading to increased exposure to and infection with C. immitis.
  • From 1940 to 2015, 47 worldwide outbreaks were reported (1,500 cases total) (3). Outbreaks occurred after an earthquake, a large dust storm, construction, archaeological sites, military maneuvers, and laboratory exposures (3).

Prevalence
Up to 17–29% of community-acquired pneumonias in endemic areas (1)

Etiology and Pathophysiology

  • C. immitis is a soil-dwelling fungus well adapted to arid conditions. The organism can remain dormant in the soil for years.
  • Liberated spores (arthroconidia) are inhaled when soil is disturbed. Upon inhalation, spores convert to spherules in the lung to cause clinical disease.
  • Infrequently, spores are introduced through a wound.

Risk Factors

  • Certain groups are more prone to dissemination:
    • Immunosuppressed patients: chemotherapy and/or immunosuppressive drugs for cancer or transplant patients, diabetes mellitus, HIV/AIDS, long-term steroid use, transplant patients, pregnancy
    • Blacks and Filipinos at higher risk
  • Previously infected patients can experience relapse years later through cell-mediated immune deficiency.
  • CNS involvement more common in young white men

General Prevention

  • No person-to-person spread
  • Lab cultures are highly contagious (inhalation); use caution when handling specimens.
  • High-risk patients should avoid archaeological digs, spelunking, or exposure to dust in endemic areas (difficult due to construction, dust storms, etc.).

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Citation

Stephens, Mark B., et al., editors. "Coccidioidomycosis." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. 5minute, www.unboundmedicine.com/5minute/view/5-Minute-Clinical-Consult/816036/all/Coccidioidomycosis.
Coccidioidomycosis. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://www.unboundmedicine.com/5minute/view/5-Minute-Clinical-Consult/816036/all/Coccidioidomycosis. Accessed June 18, 2019.
Coccidioidomycosis. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://www.unboundmedicine.com/5minute/view/5-Minute-Clinical-Consult/816036/all/Coccidioidomycosis
Coccidioidomycosis [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 June 18]. Available from: https://www.unboundmedicine.com/5minute/view/5-Minute-Clinical-Consult/816036/all/Coccidioidomycosis.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Coccidioidomycosis ID - 816036 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://www.unboundmedicine.com/5minute/view/5-Minute-Clinical-Consult/816036/all/Coccidioidomycosis PB - Wolters Kluwer ET - 27 DB - 5minute DP - Unbound Medicine ER -