Tinea Capitis

Definition

Tinea capitis is a superficial fungal infection of the scalp caused by dermatophytes, primarily affecting children, characterized by hair loss, scaling, and sometimes inflammatory plaques or pustules.

Epidemiology

• Primarily affects children aged 3–12 years; rare in adults.
• More common in males than females.
• Higher prevalence in crowded living conditions and low socioeconomic settings.
• Caused by species of Trichophyton and Microsporum.
• Transmission via direct contact with infected individuals, fomites, or animals (zoophilic species).

Etiology

• Dermatophyte fungi: Trichophyton tonsurans, Trichophyton violaceum, Microsporum canis, Microsporum audouinii.
• Transmission: direct contact with infected scalp, hair, combs, hats, or animals.
• Risk factors: poor hygiene, shared combs/hats, immunodeficiency, close contact in schools or households.

Pathophysiology

• Fungi invade keratinized structures of the scalp (hair shaft, follicles).
• Elicits an inflammatory response, leading to scaling, erythema, and hair fragility.
• Fungal spores can remain viable on fomites, leading to transmission.
• Inflammatory variants (kerion) involve intense neutrophilic infiltration, forming boggy plaques.