Scalp Mycobiota Alterations Associated with Pediculosis: A Case–Control Study

Pediculosis is one of the most common ectoparasitic infestations of school-age children worldwide. While numerous clinical features have been described, little is known about its effect on the scalp mycobiome. The study aims to determine whether active Pediculosis is associated with changes in scalp fungal colonization and diversity. From April to July 2025, a case-control study was conducted in primary schools in Nineveh, Iraq. A total of 100 female children were recruited, of whom 50 were head louse-infested, and 50 were louse-free controls. Scalp swabs were cultured on Sabouraud dextrose agar. Fungal isolates were identified by morphology and confirmed by PCR and Sanger sequencing. Fungal growth was significantly lower in patients with pediculosis compared with controls (34.0% vs. 78.0%; χ² = 19.64, p < 0.001). Patients had an 85% lower likelihood of fungal growth compared to controls (OR = 0.15, 95% CI: 0.06–0.35), whereas controls had markedly higher odds of a positive culture (OR = 6.88, 95% CI: 2.82–16.74). Culture-negative specimens were approximately three times more frequent in the patient group (66.0% vs. 22.0%). Fungal diversity was substantially lower among children with infestation. Penicillium chrysogenum predominated in controls (30.0%) but was markedly suppressed in patients (6.0%). Neoscytalidium hyalinum, an emerging dermatological and systemic pathogen, was identified exclusively among patients with louse infestation. Active pediculosis is strongly associated with reduced scalp fungal colonization and lower scalp fungal diversity. These findings suggest that head lice infestation may alter the scalp microenvironment in a manner unfavorable to fungal growth.