Description

Coccidioidomycosis, or “Valley fever,” is a disease caused by the fungus Coccidioides spp., found in the soil of disease-endemic areas. The disease is acquired by inhalation of fungal conidia from dust found in ambient air or generated by soil-disrupting human activities or natural disasters (1-3).

Occurrence

Coccidioides spp. are endemic in arid regions. In the United States, the areas with the highest incidence are primarily in the Sonoran desert in Arizona (Phoenix and Tucson metropolitan areas) and the San Joaquin Valley in California. Other endemic areas in the United States include parts of New Mexico, western Texas, and Utah (4,5). Outside the United States, coccidioidomycosis is endemic in parts of Argentina, Brazil, Colombia, Guatemala, Honduras, Mexico, Nicaragua, Paraguay, and Venezuela (3,5,6). Up to 29% of community-acquired pneumonias in endemic areas may be due to Coccidioides spp (7).

Risk for Travelers

In disease-endemic areas, persons may be at increased risk for disease if they participate in, or are present during, activities that disturb the ground and result in exposure to dust, including construction, landscaping, mining, agriculture, archaeologic excavation, military maneuvers, and recreational pursuits such as dirt biking (5,8,9). However, cases may also occur after travel to an endemic area in the absence of these exposures (6). Natural events such as earthquakes or windstorms that result in generation of dust clouds increase the risk of exposure (1). Coccidioidomycosis is not transmitted from person to person.

Clinical Presentation

The incubation period ranges from 7 to 21 days. Most infections (60%) are asymptomatic. Symptomatic persons will generally have disease ranging from a self-limited influenza-like illness characterized by fever, headache, rash, muscle aches, dry cough, weight loss, and malaise, to primary pulmonary coccidioidomycosis, characterized by pneumonia with changes on chest radiography. 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 (4,5,7,10). Persons at increased risk for severe pulmonary disease are the elderly and those with diabetes, recent smoking history, and low socioeconomic status (11). Persons at increased risk for disseminated disease include African-Americans and Filipinos, those with immunocompromising conditions (e.g., HIV), and women in the third trimester of pregnancy (10-12). Once infected with Coccidioides, a person is immune to reinfection.

Prevention

Although complete prevention of infection is not possible, travelers, 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 that include wetting soil before disturbing the earth may be effective (9,13,14). Other protective measures aimed at reducing exposure to dust such as wearing well-fitted dust masks capable of filtering particles as small as 0.4 µm and using vehicles with enclosed, air-conditioned cabs can provide added protection for those with high occupational exposure to dust (9,14). No effective vaccine for coccidioidomycosis is currently available.

References

1. Schneider E, Hajjeh RA, Spiegel RA, Jibson RW, Harp EL, Marshall GA, et al. A coccidioidomycosis outbreak following the Northridge, California, earthquake. JAMA. 1997;277:904-8.
2. Park BJ, Sigel K, Vaz V, Komatsu K, McRill C, Phelan M, et al. An epidemic of coccidioidomycosis in Arizona associated with climate changes, 1998-2001. J Infect Dis. 2005;191:1981-7.
3. Chiller TM, Galgiani JN, Stevens DA. Coccidioidomycosis. Infect Dis Clin North Am. 2003;17:41-57.
4. Galgiani JN. Coccidioidomycosis: a regional disease of national importance. Rethinking approaches for control. Ann Intern Med. 1999:130:293-300.
5. Crum NF, Lederman ER, Stafford CM, Parrish JS, Wallace MR. Coccidioidomycosis: a descriptive survey of a re-emerging disease. Clinical characteristics and current controversies. Medicine (Baltimore). 2004;83:149-75.
6. Panackal AA, Hajjeh RA, Cetron MS, Warnock DW. Fungal infections among returning travelers. Clin Infect Dis. 2002;35:1088-95.
7. Valdivia L, Nix D, Wright M, Lindberg E, Fagan T, Lieberman D, et al. Coccidioidomycosis as a common cause of community-acquired pneumonia. Emerg Infect Dis. 2006;12:958-62.
8. Cairns L, Blythe D, Kao A, Pappagianis D, Kaufman L, Kobayashi J, et al. Outbreak of coccidioidomycosis in Washington state residents returning from Mexico. Clin Infect Dis. 2000;30:61-4.
9. Petersen LR, Marshall SL, Barton-Dickson C, Hajjeh RA, Lindsley MD, Warnock DW, et al. Coccidioidomycosis among workers at an archeological site, northeastern Utah. Emerg Infect Dis. 2004;10:637-42.
10. Galgiani JN, Ampel NM, Blair JE, Catanzaro A, Johnson RH, Stevens DA, et al. Practice guideline for the treatment of coccidioidomycosis. Clin Infect Dis. 2005;41:1217-23.
11. Rosenstein NE, Emery KW, Werner SB, Kao A, Johnson R, Rogers D, et al. Risk factors for severe pulmonary and disseminated coccidioidomycosis: Kern County, California, 1995-1996. Clin Infect Dis. 2001;32:708-15.
12. Woods CW, McRill C, Plikaytis BD, Rosenstein NE, Mosley D, Boyd D, et al. Coccidioidomycosis in human immunodeficiency virus-infected persons in Arizona, 1994-1997: incidence, risk factors, and prevention. J Infect Dis. 2000;181:1428-34.
13. Smith CD, Beard RR, Rosenberger HG, et al. Effect of season and dust control on coccidioidomycosis. JAMA. 1946;132:833-8.
14. Fisher FS, Bultman MW, Pappagianis D. Operational guidelines for geological fieldwork in areas endemic for coccidioidomycosis (Valley fever). Reston, VA: US Geological Survey Open-File Report. 2000:1-16.
15. Galgiani JN, Catanzaro A, Cloud GA, Johnson RH, Williams PL, Mirels LF, et al. Comparison of oral fluconazole and itraconazole for progressive, nonmeningeal coccidioidomycosis: a randomized, double-blind trial. Mycoses Study Group. Ann Intern Med. 2000;133:676-86.

Treatment

The benefit of treating persons with uncomplicated, acute primary coccidioidomycosis has not been well studied. Although some experts feel that persons without risk for severe or disseminated disease do not require treatment because the illness is self-limited, others propose treatment to reduce the intensity or duration of symptoms (10). Persons at high risk for dissemination should receive antifungal therapy when diagnosed with acute coccidioidomycosis. Additionally, persons with severe acute pulmonary disease, chronic pulmonary infection, or disseminated disease should receive antifungal therapy. However, all patients with clinically consistent coccidioidomycosis should be tested for primary infection and followed closely to monitor the course of disease and document improvement (10).

Azole antifungals, including fluconazole and itraconazole, are generally used in most infections, including acute and chronic pulmonary infections and disseminated infections (10,15). Amphotericin B is recommended in rapidly progressive infections and in pregnant women (10). The recommended duration of therapy ranges from 3 to 6 months in those with uncomplicated respiratory infection, depending on symptom resolution, to lifelong treatment in those with meningitis (10). An infectious diseases specialist should manage these patients.