Skip Navigation LinksSkip Navigation Links
Centers for Disease Control and Prevention
Safer Healthier People
Blue White
Blue White
bottom curve
CDC Home Search Health Topics A-Z spacer spacer
Blue curve MMWR spacer

Emerging Infectious Diseases Coccidioidomycosis Following the Northridge Earthquake -- California, 1994

From January 24 through March 15, 1994, 170 persons with laboratory evidence of acute coccidioidomycosis * were identified in Ventura County, California. This number -- which comprises cases identified through active surveillance -- substantially exceeds the total number of coccidioidomycosis cases (52) reported through routine passive surveillance during all of 1993 in Ventura County, which has been considered an area of low incidence for this disease. The increase in cases follows the January 17 earthquake centered in Northridge (in adjacent Los Angeles County), which may have exposed Ventura County residents to increased levels of airborne dust. The California Department of Health Services, local public health agencies, and CDC are conducting an investigation to determine the magnitude of the outbreak, risk factors for infection, and its possible association with the Northridge earthquake.

Reported by: D Pappagianis, MD, Univ of California, Davis; G Feldman, MD, M Billimek, MSH, Ventura County Public Health Dept, Ventura; L Mascola, MD, Los Angeles County Health Dept, Los Angeles; SB Werner, MD, RJ Jackson, MD, GW Rutherford, III, MD, State Epidemiologist, California Dept of Health Svcs. Emergency Response Coordination Group, National Center for Environmental Health; Office of the Director, National Institute for Occupational Safety and Health; Div of Bacterial and Mycotic Diseases, National Center for Infectious Diseases; Div of Field Epidemiology, Epidemiology Program Office, CDC.

Editorial Note

Editorial Note: Coccidioides immitis is a dimorphic fungus that grows in soil in much of the southwestern United States; infection results from inhalation of airborne C. immitis arthroconidia. Coccidioidomycosis is not transmitted from person to person. Approximately 60% of infected persons are asymptomatic; the remainder can develop a spectrum of manifestations that range from mild to moderate influenza-like illness to pneumonia to disseminated disease, including meningitis (1). Extrapulmonary coccidioidomycosis in a person infected with human immunodeficiency virus is considered an acquired immunodeficiency syndrome-defining illness (2).

Previous outbreaks of C. immitis infection have occurred in association with windborne exposures; such outbreaks illustrate the relation between environmental conditions and emergence of infectious diseases (3). Since 1990, the number of reported cases of coccidioidomycosis in California has increased substantially; most illnesses have occurred in Kern and Tulare counties in the San Joaquin Valley (1). Most cases have occurred in residents of areas where coccidioidomycosis is endemic; however, visitors to these areas also are at risk for infection.

Because the incubation period for this infection usually ranges from 1 to 4 weeks, persons who may have become infected while visiting areas where coccidioidomycosis is endemic may not become ill until after they return home, and the diagnosis may not be considered by clinicians in areas where coccidioidomycosis is not endemic. Recent environmental exposure to C. immitis may have occurred among residents of and travelers to Ventura County, Los Angeles County, or other counties in or near the San Joaquin Valley following the earthquake and its aftershocks and during clean-up activities.

Acute coccidioidomycosis can be diagnosed by serologic tests for immunoglobulin M (IgM) detection (such as tube precipitin, enzyme immunoassay, latex agglutination, or immunodiffusion), and immunoglobulin G (IgG) detection (such as immunodiffusion or complement fixation) in the presence of pneumonia or erythema nodosum and occasionally by positive sputum culture (4).

Cases of coccidioidomycosis suspected to be temporally associated with the earthquake should be reported through state and local health departments to CDC. Information about coccidioidomycosis is available from CDC's Voice Information System, telephone (404) 332-4554, and from CDC's Emerging Bacterial and Mycotic Diseases Branch, Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, at the same telephone number.


  1. CDC. Coccidioidomycosis -- United States, 1991-1992. MMWR 1993;42:21-4.

  2. CDC. 1993 Revised classification system for HIV infection and expanded surveillance case definition for AIDS among adolescents and adults. MMWR 1992;41(no. RR-17).

  3. Pappagianis D, Einstein H. Tempest from Tehachapi takes toll or Coccidioides conveyed aloft and afar. West J Med 1978;129:527-30.

  4. Einstein HE, Johnson RH. Coccidioidomycosis: new aspects of epidemiology and therapy. Clin Infect Dis 1993;16:349-56.

    • The presence of Coccidioides immitis-specific immunoglobulin M (IgM) antibody (using enzyme immunoassay or immunodiffusion) OR serologic evidence of acute C. immitis infection, by positive IgM using latex agglutination test in the presence of pneumonia or erythema nodosum OR if IgM was not available, serologic evidence of recent infection, by positive immunoglobulin G (IgG) using immunodiffusion or complement fixation tests in the presence of pneumonia or erythema nodosum OR a positive sputum culture (with no history of previous coccidioidal infection).

Disclaimer   All MMWR HTML versions of articles are electronic conversions from ASCII text into HTML. This conversion may have resulted in character translation or format errors in the HTML version. Users should not rely on this HTML document, but are referred to the electronic PDF version and/or the original MMWR paper copy for the official text, figures, and tables. An original paper copy of this issue can be obtained from the Superintendent of Documents, U.S. Government Printing Office (GPO), Washington, DC 20402-9371; telephone: (202) 512-1800. Contact GPO for current prices.

**Questions or messages regarding errors in formatting should be addressed to

Page converted: 09/19/98


Safer, Healthier People

Morbidity and Mortality Weekly Report
Centers for Disease Control and Prevention
1600 Clifton Rd, MailStop E-90, Atlanta, GA 30333, U.S.A


Department of Health
and Human Services

This page last reviewed 5/2/01