Mucormycosis is extremely rare, making it difficult to calculate incidence accurately. In a population-based epidemiological assessment, the cumulative incidence of invasive mycotic infections was 178.3 cases per million per year, with zygomycosis comprising 1.7 infections per million per year based on data from the San Francisco Bay Area (4). A recent review of mucormycosis cases at one U.S. cancer center showed that it was present in 0.7% of patients at autopsy and in 20 patients per 100,000 admissions (5). Less than 5% of cases involve normal adult hosts. Researchers estimate that the incidence in hematologic malignancy is approximately 1%. The incidence of mucor in allogeneic bone marrow transplants is 1.9%; however, most cases do not involve the central nervous system (CNS). No racial factors predisposing people to mucormycosis are known; reviews of cases from single institutions show an equal sex distribution; and mucormycosis is found in patients of a wide age range.
The major mode of disease transmission for the Zygomycetes is presumed to be via inhalation of spores from environmental sources. No reports of confirmed human-to-human transmission exist in the literature. The presence of neutropenia with an absolute neutrophil count of less than 1000/|L for one week or more poses the major risk for these patients. For patients in whom myelosuppressive therapies have been administered, and neutropenia and fever have persisted for longer than 7 to 10 days despite antibiotic therapy, a diagnosis of a fungal infection, including zygomycosis, should be suspected (Table 2).
TABLE 2 Diseases Associated with Mucormycosis (n = 145)
Disease state n
Diabetes mellitus Renal disease Renal transplant Deferoxamine toxicity Leukemia Steroid therapy Hematologic disorder No underlying disease Others (nine disorders)
Note: HIV is not an independent risk factor for mucormycosis. Source: Adapted from Ref. 6.
Was this article helpful?