Kobpat Phadungsaksawasdi

Human head lice are blood-sucking insects causing an infestation in humans called pediculosis capitis. The infestation is more prevalent in the school-aged population. Scalp itching, a common presenting symptom, results in scratching and sleep disturbance. The condition can lead to social stigmatization which can lead to loss of self-esteem. Currently, the mainstay of treatment for pediculosis is chemical insecticides such as permethrin. The extended use of permethrin worldwide leads to growing pediculicide resistance. The aim of this study is to demonstrate the presence of the knockdown resistance (kdr) mutation in head lice populations from six different localities of Thailand. A total of 260 head lice samples in this study were collected from 15 provinces in the 6 regions of Thailand. Polymerase chain reaction (PCR) was used to amplify the α subunit of voltage-sensitive sodium channel (VSSC) gene, kdr mutation (C→T substitution). Restriction fragment length polymorphism (RFLP) patterns and sequencing were used to identify the kdr T917I mutation and demonstrated three genotypic forms including homozygous susceptible (SS), heterozygous genotype (RS), and homozygous resistant (RR). Of 260 samples from this study, 156 (60.00%) were SS, 58 (22.31%) were RS, and 46 (17.69%) were RR. The overall frequency of the kdr T917I mutation was 0.31. Genotypes frequencies determination using the exact test of Hardy-Weinberg equilibrium found that northern, central, northeastern, southern, and western region of Thailand differed from expectation. The five aforementioned localities had positive inbreeding coefficient value (F_is > 0) which indicated an excess of homozygotes. The nucleotide and amino acid sequences of RS and RR showed T917I and L920F point mutations. In conclusion, this is the first study detecting permethrin resistance among human head lice from Thailand. PCR-RFLP is an easy technique to demonstrate the kdr mutation in head louse. The data obtained from this study would increase awareness of increasing of the kdr mutation in head louse in Thailand.

Background: While androgenetic alopecia (AGA) is a common condition, the concerns of youth about this condition, and how these concerns influence quality of life, personal well-being and health behaviour have been not been thoroughly investigated.Methods: Thai youth were asked to complete an AGA-related questionnaire including the dermatology life quality index, to assess their concerns and the clinical relevance. Latent class analysis was used for data analysis.Results: Data from 278 youth were collected. The mean participant age was 22 years (SD=0.79), and 57% of the participants were men; 94.6% of the participants reported any hair loss, mostly in the AGA severity of grade 1-2. A three-class model showed the best fit. Latent class 1 (LC1) participants (58%) had the lowest probabilities of concerns regarding AGA. LC2 participants (22%) had a generally low probabilities of AGA concerns, except when they were flirting, when they were with their lover and regarding how their hair looked when they were photographed. LC3 participants (20%) were the most concerned about AGA in all aspects. Compared with LC1 participants, LC3 participants were more often to use more than 3 hair styling products (relative risk, 6.7;1.5-29.6;P=0.013) and their AGA severity was more severe in both males (relative risk, 3.2;1.1-8.9;P=0.023) and females (relative risk,10.2; 3.3-31.0;P=Conclusions: Youths who are more worried about AGA experience higher AGA severity and poorer quality of life, and are more likely to use multiple hair styling products.