Activity of tea tree oil and nerolidol alone or in combination against Pediculus capitis (head lice) and its eggs.

Emanuela Di Campli,Patricia Delli Pizzi,Luigina Cellini,Mara Di Giulio,Antonia Nostro,Soraya Di Bartolomeo,Rossella Grande

doi:10.1007/s00436-012-3045-0

Emanuela Di Campli, Patricia Delli Pizzi + Show 5 more

Open Access

https://doi.org/10.1007/s00436-012-3045-0

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Abstract

Head lice infestation is an emerging social problem in undeveloped and developed countries. Because of louse resistance increasing, several long-used insecticidal compounds have lost their efficacy, and alternatives, such as essential oils, have been proposed to treat this parasitic infestation. The present study investigated the efficacy of two natural substances: tea tree (Melaleuca alternifolia) oil and nerolidol (3,7,11-trimethyl-1,6,10-dodecatrien-3-ol) against lice and its eggs. Products were used alone and in combination (ratio 1:1 and 1:2) from 8 % dilution. The in vitro effect of natural substances at different concentrations were evaluated against 69 head lice (adults and nymphs) and 187 louse eggs collected from school children in Chieti–Pescara (Central Italy) over a 6-month period. The lice mortality was evaluated for 24 h by a stereo light microscope. The ovicidal activity was monitored by microscopic inspections for 15 days. Tea tree oil was more effective than nerolidol against head lice with 100 % mortality at 30 min and 1 % concentration. On the contrary, nerolidol expressed a more pronounced ovicidal activity inducing the failure of 50 % of the eggs to hatch at 1 % concentration after 4 days; the same effect was achieved by using a twice concentration of tea tree oil. The association of the two substances both in ratios 1:1 and 1:2 combined efficaciously their insecticidal and ovicidal effect; in particular, the ratio 1:2 (tea tree oil 0.5 % plus nerolidol 1 %) acted producing both the death of all head lice at 30 min and the abortive effect of louse eggs after 5 days. These results offer new potential application of natural compounds and display a promising scenario in the treatment of pediculosis resistant cases. The development of novel pediculicides containing essential oils could be, in fact, an important tool to control the parasitic infestation.Electronic supplementary materialThe online version of this article (doi:10.1007/s00436-012-3045-0) contains supplementary material, which is available to authorized users.

Highlights

Head lice infestation is caused by Pediculus humanus capitis De Geer, belonging to the family Pediculocidae, permanent and strictly obligatory ectoparasite species-specific: it completes the entire life cycle on the scalp of man
The aim of this study was to evaluate the activity of tea tree oil and nerolidol against eggs, nymphs and adults of Pediculus capitis used alone and in combination, in ratios 1:1 and 1:2
Lice treated with tea tree oil at 1 % of concentration (A4), caused 100 % mortality after 30 min of washing (Fig. 3a)

Summary

Introduction

Head lice infestation is caused by Pediculus humanus capitis De Geer, belonging to the family Pediculocidae, permanent and strictly obligatory ectoparasite species-specific: it completes the entire life cycle on the scalp of man. The transmission may be direct, from one head to another when they are very close, or indirect, through clothing (hats, caps, headbands muffs, shawls, scarves, and jackets), the Parasitol Res (2012) 111:1985–1992 common use of hair brushes combs, through the bedding, the backs of upholstered chairs, blankets, stuffed animals, and the common use of wardrobes (Leung et al 2005)

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