Mapping Knock-Down Resistance Mutations in Head-Louse Populations in Jazan, Saudi Arabia.

INTRODUCTION: Pediculosis capitis remains a persistent public-health concern. Although pyrethroids are still the first-line treatment, their effectiveness is threatened by knock-down resistance (kdr), which arises from point mutations in the voltage-sensitive sodium channel (VSSC). This study aimed to assess the prevalence of kdr mutations in head lice populations across different regions of Jazan, Saudi Arabia. METHODS: In this study, 59 head-louse specimens from multiple regions of Jazan were analyzed by PCR amplification and Sanger sequencing of a 908-bp fragment of the VSSC α-subunit gene. RESULTS: The T917I mutation showed the highest allele frequency (0.38) and was concentrated in Jazan's southern and eastern border areas. DISCUSSION: While overall kdr prevalence in Jazan is low, targeted surveillance is warranted in these regions, where resistance appears to be emerging.