The Lethal Effects of High-Frequency Ultrasound Waves in Pediculus Humanus Capitis (Anoplura: Pediculidae) Nymphs and Adults

Abstract

Purpose: This study aimed to assess the efficacy of high-frequency ultrasound waves as a non-chemical alternative for controlling head lice (Pediculus humanus capitis) by evaluating mortality rates in adult and nymphal stages exposed to various ultrasound frequencies. Materials and Methods: A total of 1,000 head lice (adults and nymphs) collected from infested children were exposed under controlled laboratory conditions to five ultrasound frequencies (0.5, 1.0, 1.5, 2.0, and 2.5 MHz) for up to 24 hours. A control group of 200 lice was maintained under the same laboratory conditions without ultrasound exposure. Mortality was recorded at 1, 2, 4, 8, 16, and 24 hours. Results: Among the 1,000 head lice tested, ultrasonic frequencies of 1.5, 2.0, and 2.5 MHz caused the highest mortality, reaching >= 90% in adults and >= 98.3% in nymphs. In contrast, 0.5 MHz produced the lowest mortality (20-21.7%), while the control groups showed only 8.3% (nymphs) and 15.0% (adults) mortality. Most deaths occurred within 8-24 hours post-exposure. Correlation analysis revealed a strong positive relationship between mortality and exposure time (r = 0.710, p < 0.001). ANOVA confirmed significant effects of frequency on mortality (F(5, 330) = 6.845, p < 0.001), with mortality plateauing at 2.5 MHz. Probit regression estimated LT50 values of 12.1-13.4 hours for adults and 15.4-17.6 hours for nymphs at higher frequencies, compared to 22.2 and 27.3 hours, respectively, at 0.5 MHz. Conclusion: This study is the first to demonstrate the direct effect of ultrasonic sound frequencies on Pediculus humanus capitis. High-frequency ultrasound (1.5-2.5 MHz) effectively controlled head lice without the need for additional chemicals, highlighting its potential as a non-chemical pediculosis management strategy. These findings provide a basis for future research and the development of portable devices, such as hair clips or necklaces, designed to repel or inactivate lice. Incorporating high-frequency ultrasound alongside routine combing may enhance head lice control, and further studies are warranted to optimize device design and exposure parameters.