Clinical Infectious Diseases
Risk factors for severe pulmonary and disseminated coccidioidomycosis: Kern County, California, 1995–1996
In most cases, patients with coccidioidomycosis (CM) suffer nothing more than mild, influenza-like symptoms, but in severe cases, this disease can be fatal. As with many diseases, knowing who is at risk to develop severe complications can help direct management decisions. It is well known that the San Joaquin Valley in California is hyperendemic for CM, and much of our data about CM comes from research done in this area. This article provides a recent update of CM in Kern County, which is located within the San Joaquin Valley.
The authors conducted both a 2-year population-based surveillance program for CM and a retrospective case-control study of patients with CM. The surveillance program identified all the individuals between January 1, 1995, and December 31, 1996, in Kern County who were older than 18 years and had culture, histopathologic, molecular, or serological evidence of Coccidioides immitis, the fungus that causes CM. From this data set, patients with positive diagnoses between January 1, 1995, and September 30, 1996, were classified as having mild CM, severe pulmonary CM, or disseminated CM. Mild CM was defined as a mild flulike illness. These patients served as case controls. For someone to be classified as having severe pulmonary CM, there had to be radiographic evidence of pneumonia that resulted in hospitalization. Patients classified as having disseminated CM were those with extrapulmonary or miliary CM. Enrolled patients were then contacted by telephone and asked to complete a standard questionnaire. Data on demographic characteristics, outdoor activities, dust exposure, past medical history, tobacco and alcohol use, occupation, socioeconomic status, and antifungal treatment for CM were obtained. Also recorded was the number of days missed from work or school as a result of having CM.
The surveillance program identified 905 persons newly diagnosed with CM. Of these, 682 met inclusion criteria for the case-control study, and 380 were enrolled. Both univariate and multivariate analyses were performed. Univariate analysis revealed several risk factors for severe pulmonary CM and disseminated CM. Patients who acquired severe pulmonary CM were more likely to be older, more likely to be agricultural workers, and more likely to have a longer disease course. Risk factors for disseminated CM were being male, being black, being pregnant, or having a longer disease course.
Multivariate analyses showed slightly different results. Risk factors for severe pulmonary CM, as defined by an odds ratio (OR) greater than 1.0 and a 95% confidence interval (CI) that did not overlap 1.0, included diabetes (OR = 3.3, 95% CI 1.3–8.1) and smoking cigarettes within the previous 6 months (OR = 2.4, 95% CI 1.1–5.4). The administration of oral antifungal therapy decreased the OR of acquiring severe pulmonary CM to 0.3 (95% CI 0.1–0.5). Risk factors for developing disseminated CM were black race (OR = 4.6, 95% CI 1.4–15) and having an annual income of less than $15 000 (OR = 2.4, 95% CI 1.1–5.7).
The results of this study agree in large part with data published by the Centers for Disease Control and Prevention (CDC). The major limitation of this study is that only 56% of the cases that met inclusion criteria were enrolled. Nevertheless, the data are valuable. According to the CDC Web site, risk factors for disseminated CM include immunosuppression, being black or Filipino, and pregnancy. There are no specific risk factors cited for severe pulmonary CM. In this study, there were too few people of Asian descent and too few people with immunosuppression to be statistically significant. Of course, much of the CDC data comes from previous studies from Kern County, so it is not surprising that the results are consistent. Ideally, physicians can use all of these data to better identify who is at risk for complications from CM. Through both primary and secondary prevention, morbidity and mortality could be decreased. Finally, if randomized controlled trials could confirm the suggested effect of early antifungal therapy, we would have another weapon against this disease.
(Clin Infect Dis. 2001;32:708–714) N. E. Rosenstein, K. W. Emery, S. B. Werner, et al.
Article info
Identification
DOI: https://doi.org/10.1580/1080-6032(2001)012[0216:AOCL]2.0.CO;2
Copyright
© 2001 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.
