Coccidioidomycosis risk in patients with diabetes or rhematological disease

November 24, 2008

•Coccidioides species, the cause of coccidioidomycosis, are endemic to the desert soils of the southwestern United States as well as northern Mexico and limited areas of Central and South America. The organisms can become airborne with disruption of the soil, either through natural causes or activities of humans or animals. Nearly all Coccidioides infections are acquired through the inhalation of airborne arthroconidia (spores).

Are patients with rheumatological disease or diabetes mellitus at increased risk for coccidioidomycosis?

Coccidioides species, the cause of coccidioidomycosis, are endemic to the desert soils of the southwestern United States as well as northern Mexico and limited areas of Central and South America. The organisms can become airborne with disruption of the soil, either through natural causes or activities of humans or animals. Nearly all Coccidioides infections are acquired through the inhalation of airborne arthroconidia (spores).

Residence in or travel to an area where these organisms are endemic certainly increases likelihood of exposure. Persons more likely to inhale such organisms, with resultant increased risk of infection, are those who are engaged in occupational, military, or recreational activities that have high levels of dust exposure.1 Traditionally, males have been more likely to be engaged in these types of activities and, thus, more likely to acquire infection. There is no predisposition to inhalation of arthrospores and acquisition of infection based on race or an underlying medical condition.

About 60% of persons infected with Coccidioides species, as determined by a positive skin test result, have no symptoms. Those who do have symptomatic, primary pulmonary illness may experience a variety of symptoms, the most common of which are fatigue and malaise, cough, dyspnea, fever and sweats, headache, myalgia and arthralgia, and rash. Many such illnesses are mild and self-limited, while others are of moderate or high severity.

Coccidioidal illnesses are more likely to be identified and reported with increasing age. Persons who are immunosuppressed, particularly those with impaired cellular immunity, such as that caused by HIV infection, hematological malignancy, or organ transplant, and those who are receiving immunosuppressive medication, such as corticosteroids, antirejection agents following transplant, or immunomodulating agents (for example, anti–tumor necrosis factor antibodies), are at increased risk for symptomatic illness.

Fewer than 5% of persons who have coccidioidal illnesses have extrapulmonary, disseminated infections. Persons who are at higher risk for disseminated infection include those of certain racial descent (Filipino and African American persons), males, and pregnant women. Immunosuppressed persons also are at increased risk for disseminated coccidioidomycosis.

Persons with diabetes mellitus are not at higher risk for acquisition of coccidioidal infection. However, once infected, they have been reported to have severe, progressive and complicated pulmonary coccidioidal illnesses. One study reported that persons with diabetes mellitus were more likely to have cavitary pulmonary infection and relapsing coccidioidomycosis than those without diabetes mellitus; this study also found that diabetic persons whose blood glucose levels were 220 mg/dL or higher were more likely to have disseminated infection than diabetic persons whose blood glucose levels were lower than than 220 mg/dL.2

Similarly, persons with rheumatological diseases are not at higher risk for coccidioidomycosis. However, those who are being treated with corticosteroids or other immune-modifying agents, such as methotrexate and infliximab, may be more susceptible (although not inevitably so) to symptomatic illness and dissemination.3

We welcome brief questions on general clinical problems related to respiratory medicine, including brief descriptions of confusing patient situations or follow-up questions on articles we have published. The most interesting and broadly applicable queries and replies will be published. (Names will be withheld on request.) Address correspondence to the Editor, The Journal of Respiratory Diseases, 330 Boston Post Road, PO Box 4027, Darien, CT 06820-4027. You can also e-mail us via sarah.williams@cmpmedica.com.

References:

REFERENCES


1.

Laniado-Laborin R. Expanding understanding of epidemiology of coccidioidomycosis in the Western hemisphere.

Ann N Y Acad Sci.

2007;1111:19-34.

2.

Santelli AC, Blair JE, Roust LR. Coccidioidomycosis in patients with diabetes mellitus.

Am J Med.

2006;119:964-969.

3.

Mertz LE, Blair JE. Coccidioidomycosis in rheumatology patients: incidence and potential risk factors.

Ann N Y Acad Sci.

2007;1111:343-357.