First Molecular Investigation of VSSC-Linked Permethrin Resistance in Human Scabies in Turkiye

Objective: Scabies, a longstanding public health concern, is a contagious and pruritic skin condition caused by the parasite Sarcoptes scabiei, affecting an estimated 300 million individuals worldwide annually. Recent increases in incidence can be attributed to challenges in accurate diagnosis and instances of treatment resistance. Permethrin, an insecticide belonging to the pyrethroid group, is the primary choice for scabies treatment. However, recent treatment failures suggest the emergence of permethrin resistance. Pyrethroids, widely employed as insecticides over the past three decades, have led to resistance development across various organisms. Pyrethroid acaricides like permethrin target the neuronal voltage-sensitive sodium channel (VSSC) protein, crucial for action potential generation in excitable cells. Specific mutations in the VSSC gene have been associated with pyrethroid resistance. Our objective is to elucidate the correlation between treatment failure and pyrethroid resistance stemming from VSSC gene mutations in Sarcoptes scabiei mites responsible for scabies cases in the Sivas region, Türkiye. Methods: In this study, we analyzed 30 scabies cases where initial permethrin treatment proved ineffective. The VSSC gene of scabies mites was partially isolated from genomic DNA to identify potential mutations via DNA sequencing. Results: Results yielded significant insights into the relationship between permethrin resistance and VSSC gene mutations. Notably, 43.3% of mites exhibited mutated VSSC genes. Conclusion: This study represents the first investigation into Vssc-associated permethrin resistance in human scabies. The study highlights the importance of detecting genotypic resistance in 43.3% of phenotypically resistant cases.