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

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. 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. The T917I mutation showed the highest allele frequency (0.38) and was concentrated in Jazan's southern and eastern border areas. While overall kdr prevalence in Jazan is low, targeted surveillance is warranted in these regions, where resistance appears to be emerging.