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Coccidioidomycosis -- Arizona, 1990-1995

MMWR 45(49);1069-1073

Publication date: 12/13/1996

Table of Contents


Editorial Note



Number of reported cases of coccidiodomycosis, by year ...
Mean annual incidence rate of coccidiodomycosis, by age group ...


Coccidioidomycosis is a systemic infection caused by the inhalation of airborne arthroconidia from Coccidioides immitis, a soil-dwelling fungus found in the southwestern United States, parts of Mexico, and Central and South America (1). Clinical manifestations occur in approximately 40% of infected persons and may include mild influenza-like illness; severe pneumonia; and rarely, disseminated disease and death (2). During 1990-1995, the number of reported cases of coccidioidomycosis in Arizona increased by 144%. To characterize trends in and the impact of coccidioidomycosis in Arizona, the Arizona Department of Health Services (ADHS) analyzed surveillance, death-certificate, and hospital discharge data. This report summarizes the findings, which indicate that, during 1990-1995, coccidioidomycosis in Arizona disproportionately affected persons aged greater than or equal to 65 years and persons with human immunodeficiency virus (HIV) infection.


Surveillance data were compiled from the ADHS' General Communicable Disease Reporting System. In 1994, ADHS adopted the surveillance case definition for coccidioidomycosis proposed by the Council of State and Territorial Epidemiologists, which requires the presence of clinically compatible symptoms and laboratory evidence of infection * (3). Before 1994, ADHS relied solely on physician diagnosis of coccidioidomycosis and did not require laboratory confirmation. Incidence rates were calculated using 1990 census data adjusted to reflect Arizona's estimated annual population growth.

During 1980-1989, the annual number of reported cases of coccidioidomycosis in Arizona remained relatively stable (median: 211, range: 191-342) (Figure 1). During 1990-1995, a total of 2762 cases of coccidioidomycosis were reported to ADHS, and the annual number of reported cases increased from 255 (7.0 cases per 100,000 population) in 1990 to 623 (14.9 cases per 100,000 population) in 1995. The median age of case-patients was 51 years (range: less than 1 year-100 years), and most (1731 {63%}) occurred among males. Of the 2762 total cases, 1101 (40%) had pulmonary disease; 96 (3%), disseminated disease; and 1565 (57%), other or unspecified disease.

During 1990-1995, annual incidence rates for coccidioidomycosis were highest among males (range: 8.2-19.3 per 100,000 population) and persons aged greater than or equal to 65 years (range: 14.6-35.0 per 100,000). During this period, annual rates increased within each age group. Mean annual rates increased from 1.8 per 100,000 population for persons aged 0-4 years to 28.0 per 100,000 for persons aged greater than or equal to 65 years (Figure 2). Three counties (Maricopa, Pima, and Pinal) located in the Sonora Desert accounted for approximately 79% of Arizona's population and 93% of all cases statewide; the highest annual rates in these counties were 16.4, 23.6, and 30.1, respectively.

Because surveillance data did not indicate disease outcome, death certificates were reviewed to determine mortality from coccidioidomycosis. During 1990-1994 (the latest year for which death-certificate data were available), coccidioidomycosis was listed as the underlying cause of death for 134 persons, and the annual number of deaths increased from 21 in 1990 to 37 in 1994. Hospitalizations

Data from the Arizona Hospital Discharge Database (AHDDB) were used to determine the impact of coccidioidomycosis-related hospital admissions in 1993. The AHDDB documents the first five discharge diagnoses for persons admitted to nonfederal hospitals in Arizona. The AHDDB was reviewed to identify patients with a discharge diagnosis of coccidioidomycosis (International Classification of Diseases, Ninth Revision, Clinical Modification {ICD-9-CM}, codes 114.0-114.3 and 114.9). Because unique patient identifiers were not available, patients were identified by date of birth, sex, and zip code.

During 1993, a total of 659 patients had coccidioidomycosis among their first five discharge diagnoses; for 415 (63%), coccidioidomycosis was listed as the principal diagnosis. The discharge diagnoses for these 659 patients included primary pulmonary coccidioidomycosis (66%), progressive coccidioidomycosis (20%), coccidioidal meningitis (6%), unspecified coccidioidomycosis (6%), and primary extrapulmonary coccidioidomycosis (0.1%); 1% of patients were discharged with multiple coccidioidomycosis diagnoses; and 72 (11%) died. Comorbid conditions in these 72 patients included HIV infection (32 {44%}), chronic lung disease (13 {18%}), allogeneic organ transplantation (four {6%}), and other conditions (23 {32%}). Although the hospitalization rate was highest among persons aged greater than or equal to 60 years (39 per 100,000 population), the case-fatality rate was highest among patients aged 30-39 years (17%).
During 1993, direct hospital costs for all coccidioidomycosis-related admissions for the 659 patients totaled approximately $19 million, with an average cost per hospitalization of $23,889 and an average length of stay of 10 days (range: 1-125 days).

In 1993, a total of 973 patients had a discharge diagnosis of HIV infection; of these, 98 (10%) also had a discharge diagnosis of coccidioidomycosis, and 32 (33%) of these 98 patients died. In comparison, of patients with a discharge diagnosis of HIV infection but without coccidioidomycosis, 15% died, and of patients with a discharge diagnosis of coccidioidomycosis without known HIV infection, 7% died.

Reported by: D Mosley, K Komatsu, V Vaz, D Vertz, B England, MD, State Epidemiologist, Arizona Dept of Health Svcs; NM Ampel, Univ of Arizona, Tucson. Veterans Affairs Medical Center, Atlanta, Georgia. Surveillance Br, Div of HIV/AIDS Prevention, National Center for HIV, STD, and TB Prevention; Childhood and Respiratory Diseases Br, Div of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: The findings in this report indicate that the incidence of coccidioidomycosis in Arizona increased substantially during 1990-1995; in addition, coccidioidomycosis disproportionately affected persons aged greater than or equal to 65 years and persons with HIV infection. The increase in incidence may have reflected, in part, an increase in Arizona in the number of older residents, an increase in the number of HIV-infected persons with AIDS, and weather conditions.

During 1990-1995, the number of Arizona residents aged greater than or equal to 65 years increased by 22%. Many of these persons may have moved to the state from areas where coccidioidomycosis is not endemic and, therefore, were more susceptible to infection than those who had been long-term residents of Arizona. In addition, older adults may be at increased risk for developing symptomatic illness following infection with C. immitis (4) because of host factors (e.g., chronic lung disease and other underlying medical conditions) and may be more likely to seek medical attention following onset of respiratory symptoms. Because the denominator does not include persons who temporarily move to Arizona during the winter, incidence rates in this report for persons aged greater than or equal to 65 years probably were slightly overestimated.

During 1990-1995, the prevalence of AIDS in Arizona increased by at least 79%, from 938 to 1683 (1995 data are provisional). The high prevalence of coccidioidomycosis among HIV-infected persons is consistent with previous reports documenting severe coccidioidomycosis as a common opportunistic infection among HIV-infected populations in areas where coccidioidomycosis is endemic (5-7).

Severe drought followed by heavy rainfall was identified as a factor possibly associated with the recent epidemic of coccidioidomycosis in California (8); this weather pattern may be important in facilitating the growth of C. immitis and the airborne spread of arthroconidia to humans. Although meteorologic data have not been analyzed, climatic factors also may have played an important role in the recent increase in coccidioidomycosis in Arizona.

Although coccidioidomycosis cannot be readily prevented (8), improved understanding of the epidemiology of this disease can assist in developing more effective prevention strategies. Efforts should include 1) increasing awareness of this disease among clinicians and the public, especially visitors to Arizona (and other areas where coccidioidomycosis is endemic) from areas where coccidioidomycosis is not endemic; 2) promoting more complete reporting of coccidioidomycosis cases by encouraging clinical laboratories to report all specimens positive for C. immitis; 3) better characterizing the environmental and host factors for acquiring infection, especially for older persons and HIV-infected persons; 4) conducting studies to evaluate the effectiveness of chemoprophylaxis for preventing coccidioidomycosis in persons with AIDS or other immunosuppressive conditions who live in areas where coccidioidomycosis is endemic; and 5) developing an effective vaccine that confers lasting immunity against C. immitis.



  1. Pappagianis D. Epidemiology of coccidioidomycosis. In: McGinnis M, ed. Current topics in medical mycology. Vol 2. New York, New York: Springer Verlag, 1988:199-238.
  2. Drutz DJ, Catanzaro A. Coccidioidomycosis. Am Rev Respir Dis 1978;117:559-85,727-71.
  3. Council of State and Territorial Epidemiologists. Case definitions for public health surveillance. Presented at the Council of State and Territorial Epidemiologists National Surveillance Conference, Atlanta, Georgia, November 30-December 2, 1994.
  4. Hajjeh R, Schneider E, Spiegel R, et al. An outbreak of coccidioidomycosis in Ventura County, California, following the Northridge Earthquake {Abstract no. J185}. Presented at the 34th Interscience Conference on Antimicrobial Agents and Chemotherapy. Orlando, Florida, October 1994.
  5. Ampel NM, Dols CL, Galgiani JN. Coccidioidomycosis during human immunodeficiency virus infection: results of a prospective study in a coccidioidal endemic area. Am J Med 1993;94:235-40.
  6. Singh VR, Smith DK, Lawrence J, et al. Coccidioidomycosis in patients infected with human immunodeficiency virus: review of 91 cases at a single institution. Clin Infect Dis 1996;23:563-8.
  7. Jones JL, Fleming PL, Ciesielski CA, Hu DJ, Kaplan JE, Ward JW. Coccidioidomycosis among persons with AIDS in the United States. J Infect Dis 1995;171:961-6.
  8. CDC. Update: coccidioidomycosis -- California, 1991-1993. MMWR 1994;43:421-3.
* The laboratory criteria for diagnosis are cultural, histopathologic, or molecular evidence of the presence of C. immitis; a positive serologic test for coccidioidal antibodies in serum or cerebrospinal fluid by 1) detection of coccidioidal immunoglobulin M by immunodiffusion, enzyme immunoassay (EIA) latex agglutination, or tube precipitin or 2) detection of rising titer of coccidioidal immunoglobulin G by immunodiffusion, EIA, or complement fixation; or a coccidioidal skin test conversion from negative to positive after the onset of clinical signs and symptoms.


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Figure 1

Number of reported cases of coccidiodomycosis, by year ...

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Figure 2

Mean annual incidence rate of coccidiodomycosis, by age group ...

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