Head lice in progress: what could/should be done—a report on an in vivo and in vitro field study

Ovicidal effect of essential oils from Zingiberaceae plants and Eucalytus globulus on eggs of head lice, Pediculus humanus capitis De Geer

BACKGROUND

Head lice infestation is an important public health problem worldwide. Chemical pediculicides have lost their efficacy because lice have developed resistance to them. Therefore, alternative pediculicides such as essential oils and herbal products have been proposed for treating head lice infestation.

STUDY DESIGN

To determine the efficacy of essential oils from three Zingiberaceae plants (Curcuma xanthorrhiza, Curcuma zedoaria and Zingiber zerumbet) against head lice eggs and to investigate an augmenting substance (Eucalyptus globulus EO) for improving the efficacy of these essential oils in killing head lice eggs, especially on the inhibition of their hatching process. Permethrin pediculicide, soyabean oil, and drinking water were used as positive, negative, and neutral controls, respectively.

METHODS

An immersion test was used to evaluate the ovicidal activity of 12 essential oil formulations. Head lice eggs were immersed for 1, 5 and 10 min in the treatments. Mortality rate was observed on day 7 and day 14; mortality was checked under a stereomicroscope.

RESULTS

All head lice eggs that were immersed in a combination of 10% C. zedoaria EO and 10% E. globulus EO for 5 min did not hatch at all for 7-14 days of incubation. All head lice eggs that were immersed in soyabean oil and drinking water for 1, 5, and 10 min showed 100% hatching rate in 7-14 days of incubation. All head lice eggs that were immersed in permethrin pediculicide for 1, 5 min, showed 100% hatching rate, but when they were immersed for 10 min, permethrin provided 4.0-6.0% inhibition rate with 94.0-96.0% hatching rate for 7-14 days of incubation. All combinations of Zingiberaceae EOs and E. globulus EO at low and high concentrations (5 and 10%) exhibited high ovicidal activities against head lice eggs, and the combinations showed a synergistic effect with an increase in the inhibition rate of more than 50%.

CONCLUSION

These results demonstrated that Zingiberaceae EOs augmented with E. globulus EO are promising ovicidal agents for head lice control.

Randomized, investigator-blinded, controlled clinical study with lice shampoo (Licener®) versus dimethicone (Jacutin® Pedicul Fluid) for the treatment of infestations with head lice

The present clinical trial was conducted to obtain additional data for the safety and efficacy of a head lice shampoo that is free of silicone compared with an anti-head lice product containing dimethicone. Both products act by a physical mode of action. This randomized, investigator-blinded, controlled clinical study was conducted between July and November 2016 in households of two villages (Abou Rawash and Shandalat) in Egypt. Children older than 2 years with an active head lice infestation were treated with either a shampoo-based head lice treatment containing neem extract (Licener®) or dimethicone (Jacutin® Pedicul Fluid) on day 1 and additionally on day 9. Assessment for living lice by combing was conducted before and 1-2 h after treatment and on days 5 and 13. The main objective was to demonstrate a cure rate of the test product of at least 85% after a single application (day 5 and 9). Secondary objectives were to scrutinize patient safety and satisfaction as well as cure rates on day 13 after two treatments and the evaluation of ovicidal and licicidal efficacies of the products. Sixty-one children in the test-group (Licener®) and 58 children in the reference group (Jacutin® Pedicul Fluid) were included in this study. The test product and the reference product were very well tolerated. Both products exceeded the objective of cure rates of over 85% after single treatment (test group 60/60 = 100%; 95% CI = 94.04-100.00%; reference group 54/57 = 94.74%; 95% CI = 85.38-98.90%; p = 0.112; CI by Clopper-Pearson) and after two treatments (test group 58/58 = 100%; 95% CI = 93.84-100.00%; reference group 52/54 = 96.30%; 95% CI = 87.25-99.55%; p = 0.230) with higher cure rates and non-inferiority for the test product. The combined success rate shows significant superiority of the test product against the reference product (test group 58/58 = 100%; 95% CI = 93.84-100.00%; reference group 49/54 = 90.7%; 95% CI = 79.70-96.92%; p = 0.024). The test product showed higher ovicidal efficacy than the reference product. Thus, the present study demonstrates that a single treatment with a head lice product like Licener® can be sufficient to eliminate a head lice infestation.

Flammability testing of 22 conventional European pediculicides

Lice have been parasitizing humans for at least 10,000 years. Since then, humans have tried to rid themselves of these unpleasant and potentially disease-carrying insects. Despite various plant extracts and chemical compounds being used to combat recurring infestations to this date, several lice populations have developed resistance to some of the abundantly used compounds. This resulted in the development of anti-louse products that physically kill the different lice stages. Today, a widely used group of delousing agents are dimethicones (polydimethylsiloxane PDMS) which function by suffocating the lice. However, many dimethicones and related products are highly flammable which makes them potentially dangerous for treatment. In the present study, we tested the flammability of 22 delousing agents in order to shed some light onto this currently unresolved problem in the product design of pediculicides. Thirteen products were easily ignitable, some even by distant contact with a sparkler.