Poultry Favus Study Guide

Overview and Clinical Importance

Favus (also known as avian ringworm or white comb) is a chronic, superficial fungal infection of poultry caused primarily by the dermatophyte Microsporum gallinae. This zoophilic fungus targets keratin-rich, non-feathered skin structures including the comb, wattles, earlobes, and occasionally the shanks. While favus is considered a disease of minor importance in modern commercial poultry operations, it remains clinically relevant in backyard flocks, exhibition birds, and fighting cocks, making it a potential NAVLE topic.

The condition derives its name from the Latin word favus meaning honeycomb, describing the characteristic cup-shaped crusty lesions (scutula) that form in advanced cases. First described by Megnin in 1881, this dermatophyte was originally classified as Epidermophyton gallinae before reclassification. Understanding favus is important for the NAVLE as it tests knowledge of fungal diseases, zoonotic potential, and dermatological conditions in poultry.

Etiology

Primary Causative Agent

Microsporum gallinae (synonyms: Lophophyton gallinae, Epidermophyton gallinae, Achorion gallinae) is the primary etiologic agent. This zoophilic dermatophyte is a keratinophilic fungus that utilizes keratin as its primary nutrient source through production of keratinase enzymes.