Fungal primary and opportunistic pathogens: an ecological perspective

Area of Science:

• Mycology
• Pathogenesis
• Evolutionary Biology

Background:

• Fungal pathogenicity in vertebrates is often viewed as opportunistic, relying on host tissue for survival.
• Primary fungal pathogens represent a deliberate strategy for species fitness, distinct from opportunistic infections.

Purpose of the Study:

• To redefine fungal primary pathogenicity as a strategic adaptation.
• To differentiate between opportunistic and primary fungal pathogens based on host interaction and transmission.
• To explore the evolutionary implications of fungal pathogenicity strategies.

Main Methods:

• Conceptual analysis of fungal life cycles and host-pathogen interactions.
• Review of existing literature on fungal pathogenesis and evolution.
• Definition and categorization of fungal pathogenicity types.

Main Results:

• Primary pathogenicity is a deliberate strategy where the host aids fungal fitness.
• Opportunism involves coincidental survival without transmission, hindering fungal evolution.
• Primary pathogens are categorized by transmission: environmental (enzootic) or host-to-host (epidemic).
• Extremotolerance facilitates shifts from opportunistic to primary pathogenicity by enabling survival in new niches.

Conclusions:

• Fungal pathogenicity is an evolved strategy, not solely opportunistic.
• Transmission modes dictate evolutionary potential and disease patterns (enzootic vs. epidemic).
• Environmental adaptability, particularly extremotolerance, is key for fungi to transition to primary pathogenicity.