Clinical Syndromes: Mucormycosis

Abstract

Mucormycosis has emerged as an important fungal infection with high morbidity and mortality. The genera Rhizopus, Lichtheimia, and Mucor are most often recovered from clinical specimens and are ubiquitous in nature, but their precise ecology remains to be determined. Cases with mucormycosis have been reported from all over the world, and seasonal variation is possible. Israel reported that 16 of 19 rhino-orbitocerebral mucormycosis cases occurred in autumn [1], and in Japan, 6 of 7 pulmonary mucormycosis cases developed from August to September [2]. However, others report invasive cases all of the year [3–7]. There are several factors that limit our ability to accurately determine the exact incidence of mucormycosis. First, these infections are not reportable; the risk varies widely in different populations, and the proof of diagnosis is extremely difficult to obtain. Mucormycosis remains an uncommon disease, even in high-risk patients, and represents between 4 and 23% of all fungal infections in patients at risk [3–5]. Postmortem evaluation showed mucormycosis being 10–50-fold less frequent than candidiasis or aspergillosis with a frequency of 1–5 cases per 10,000 autopsies [3–7]. The epidemiology of mucormycosis varies between developed and developing countries. In developed countries the disease is most often seen in patients with hematological malignancies undergoing chemotherapy or who received allogeneic stem cell transplants (HSCT) [8]. Roden et al. compiled 929 cases of mucormycosis and displayed an increasing proportion of immunocompromised patients with mucormycosis in the 1980s and 1990s [9]. The registry of the European Confederation of Medical Mycology Working Group recorded 230 cases between 2005 and 2007 and found patients with hematological malignancies (44%), trauma (15%), HSCT (9%), and diabetes mellitus (9%) being infected [10]. Similar data were obtained by a French analysis comprising 101 cases of mucormycoses (60 proven and 41 probable cases), mostly in men (58%) older than >50 years (mean age, 50.7 ± 19.9 years). The incidence increased from 0.7 cases per 1 million in 1997 to 1.2 cases per 1 million in 2006 (P < 0.001) [11]. An active population-based surveillance study from California calculated an annual incidence of mucormycosis of 1.7 cases per 1 million individuals (∼500 cases per year) [12]. An incidence of 0.43 cases per 1 million inhabitants or 0.62 cases per 100,000 hospital admissions was rated for Spain [13]. In developing countries, especially in India, mucormycosis occurs mainly in patients with uncontrolled diabetes or trauma [14, 15].