In vitro efficacy of five essential oils against Pediculus humanus capitis

A new study has assessed the in vitro efficacy of five essential oils against adults of Pediculus humanus capitis using a contact filter paper toxicity bioassay and revealed that Clove oil diluted either in coco oil or sunflower oil demonstrated the best adulticidal activity reaching over 90% within 2 hours in lice submitted to a 30 minute contact.

The study by Candy K., et al., published in the December 2017 Journal of Parasitology Research involved analysing the chemical composition of the essential oils from wild bergamot, clove, lavender, tea tree, and Yunnan verbena using chromatography-mass spectrometry. All treatments and controls were replicated three times on separate occasions over a period of 11 months. In all, 1239 living lice were collected from the scalp of 51 subjects, aged from 1 to 69 years.

The study revealed that the oil’s major component(s) differed according to the tested oils and appeared chemically diverse. In the case of clove oil, the eugenol appeared as the main component. The study also revealed that Yunnan verbena oil diluted in coco oil showed also showed a significant efficacy but other essential oils showed a lower efficacy confirming the potential interest of some of the essential oils tested but not all.