Fungal infections, systemic

Systemic fungal infections have increased markedly in frequency and importance in recent decades, primarily because advances in the treatment of serious diseases and the ongoing human immunodeficiency virus (HIV) epidemic have expanded the population of people with abnormal host defenses against infections. Key aspects of host defenses against fungal infection include anatomical barriers such as the skin and mucosal surfaces, innate and adoptive immune responses, and nutritional immunity. Recent advances in our understanding of fungal pathogenesis include the discovery of mating systems in several pathogenic fungi, development of molecular genetic tools for deleting genes or regulating their expression, the sequencing of the genomes of several pathogenic fungi, and the use of newer nucleic acid sequencing technologies to analyze and quantify global gene expression. Blastomyces, Coccidioides, Histoplasma, Paracoccidioides, and Sporothrix are true pathogens that can cause disease in people with normal or abnormal host defenses. In contrast, Aspergillus, Candida, Cryptococcus, Penicillium, Pneumocystis, and the zygomycetes are opportunistic pathogens that tend to cause serious disease only in people with abnormal host defenses. The key properties of each of these fungi are reviewed, along with the epidemiology, pathogenesis, clinical features, methods for diagnosis, and treatment of the corresponding fungal diseases.