Fungi that Infect Humans

Area of Science:

• Medical Mycology
• Pathogen Evolution
• Fungal Pathogenesis

Background:

• Fungi must meet four criteria for human infection: thermotolerance, barrier penetration, tissue lysis/absorption, and immune evasion.
• Host immune systems co-evolved with fungi, limiting infections in healthy individuals.
• Modern medicine, by compromising immune defenses, creates new opportunities for fungal pathogens.

Purpose of the Study:

• To explore the diverse strategies employed by fungi across four phyla to meet the criteria for human infection.
• To highlight unique traits that confer pathogenic potential in various fungal species.
• To discuss the evolutionary interplay between hosts and fungi, including commensalism and parasitism.

Main Methods:

• Review of fungal pathogenic mechanisms across four major phyla: Entomophthorales, Mucorales, Ascomycota, and Basidiomycota.
• Examination of specific fungal genera and species with known human pathogenic potential.
• Consideration of evolutionary pressures shaping fungal and host genomes and physiology.

Main Results:

• Fungal pathogenesis involves strategies like morphogenesis for barrier traversal and enzyme secretion for nutrient acquisition.
• Pathogenic fungi include thermal dimorphs (e.g., Histoplasma, Coccidioides), opportunistic pathogens (e.g., Cryptococcus, Candida, Aspergillus, Pneumocystis), and agents of neglected tropical diseases.
• Fungal traits, from thermal dimorphism to immune evasion, are key to their success as human pathogens.

Conclusions:

• Fungal infection is a complex interplay of fungal adaptation and host defenses.
• Understanding fungal strategies is vital, especially with increasing host susceptibility due to medical interventions.
• Evolutionary dynamics, including host-pathogen interactions, continue to shape fungal pathogenicity.