Comparative Efficacy of Commercial Antilice Shampoos Against Head Lice in a High-Prevalence Primary School in Thailand.

This is a cross-sectional study that is aimed at evaluating the efficacy of antilice shampoo against head lice infestation in primary schoolgirls at level 3-6 (aged between 9 and 12 years) with a high prevalence of infestation in Pathum Thani Province and which also reported a current prevalence of lice infestation in this school. The study was conducted during January-March 2023. A total of 356 schoolchildren were screened for lice infestation. The prevalence rate of lice infestation was found in 78 students (21.9%) from all schoolchildren. Girls (50.3%) showed a higher rate of lice infestation than boys (0.5%) with a significant difference ( < 0.05). Most lice-infested girls (100%) reported itching. Seventy-two of 77 infested girls (93.5%) agreed to use shampoos for lice treatment. Two types of commercial shampoos were considered for lice treatment: (1) chemical (permethrin 0.5% W/V) antilice shampoo and (2) herbal antilice shampoo, since it is cheap and available in the market. The results of chemical (permethrin 0.5% W/V) antilice shampoo showed similar efficacy for lice treatment as herbal antilice shampoo with no significant difference in statistics ( > 0.05). Using the antilice shampoos consecutively 3 times demonstrated the highest efficacy of treatment (73.0%), followed by 2 times (34.3%), and the lowest efficacy of treatment was a single application (5.6%). No serious side effects from both shampoos in participants: 2 cases of itching and 1 case of the burning sensation. This indicated that in the area of the high prevalence of lice infestation, herbal antilice shampoo might be an alternative choice for lice treatment. However, we recommended using it once a week 3 times consecutively to reach the highest efficacy for treatment. In addition, this treatment should be extended to family members with lice infestation.