Prevalence, Risk Factors, and Phylogenetic Characterization of Pediculus humanus capitis Among Primary Schoolchildren...

Pediculus humanus capitis is a cosmopolitan ectoparasite that causes scalp pruritus, particularly among children in low- and middle-income countries. Transmission occurs mainly through direct head-to-head contact, and various risk factors have been implicated in increasing susceptibility to infestation. Nevertheless, epidemiological and molecular data on head lice infestation in Algeria remain limited.

This cross-sectional epidemiological study aimed to estimate the prevalence of pediculosis capitis and to identify associated risk factors among Algerian primary schoolchildren across 21 provinces over a 10-year period (2015-2024). A total of 34,152 children aged 8 to 11 years from 124 schools were screened for infestation. Data were collected on infestation status, demographic variables, and hair characteristics. In addition, mitochondrial cytochrome b gene sequencing was performed on representative specimens to investigate phylogenetic diversity and lineage distribution.

The overall prevalence of head lice infestation was 3.5%, with a mean intensity of 7.8 lice per infested individual and a mean abundance of 0.23 lice per child. Significant regional and annual variations in prevalence were observed. Infestation was nearly four times higher in girls than in boys (5.18% vs. 1.58%; OR = 3.53, p < 0.001). Additional risk factors included long, straight hair and poor scalp hygiene. Phylogenetic analysis revealed the co-circulation of two mitochondrial clades (A and B), with a slight predominance of clade A, indicating underlying genetic diversity and regional heterogeneity in lineage distribution.

This first large-scale national survey integrating epidemiological and phylogenetic approaches provides a comprehensive overview of head lice infestation in Algeria. The findings support the implementation of targeted school-based prevention programs and highlight the importance of molecular surveillance to better understand lice population structure and to inform sustainable control strategies.