Changing Epidemiology of Classical and Emerging Human Fungal Infections: A Review

In recent decades, many fungal species have emerged as major causes of human disease. While invasive candidiasis, aspergillosis, and cryptococcosis remain very common, rates of infection by other opportunistic fungal pathogens such as Histoplasma capsulatum, Coccidioides immitis, Fusarium spp. and other yeasts and molds are on the rise. Adding to this bleak picture is the fact that treatment and control measures currently available to us are hardly able to keep up with current trends of morbidity and mortality that associate with common and emerging fungal infections. It is interesting to note the likelihood of emerging fungal pathogens exhibiting significant resistance to standard antifungal therapy is real. Hence, invasive infections due to previously rare fungi such as Acremonium, Scedosporium, Paecilomyces, and Trichoderma species are proving difficult to treat. The ever increasing number of hosts with compromised immunity, increased volume of surgeries and invasive medical procedures, limited repertoire of and increased resistance to available antifungals, and better diagnosis and pathogen identification procedures are largely to blame for these alarming trends. Improvements in managing patients with cancer, AIDS, diabetes, and transplantation that are significantly improving patient survival rates are also generously contributing to the pool of patients with compromised immunity. In this article, we review the changing spectrum of invasive mycosis, risk-factors for infections and susceptibility to available antifungals.