Li Meilin,Liu Shunlong,Yin Zhijuan,Bernigaud Charlotte,Guillot Jacques,Fang Fang
Background The limited ovicidal activity of currently available acaricides is a significant obstacle to efficacious scabies treatment. Several essential oils or their respective components have proved to be active against the eggs of arthropods, mainly lice and ticks. Information on the activity of these oils and/or components against the eggs of mites remains very limited. The aim of this study was to assess the activity of six terpenes (carvacrol, eugenol, geraniol, citral, terpinen-4-ol and linalool) commonly found in essential oils against the eggs of Sarcoptes scabiei . Methods Sarcoptes eggs were exposed to paraffin oil containing 1, 2.5, or 5% of each terpene tested. After a 12-h exposure period, the eggs were washed and placed in paraffin oil for hatching. Embryonic development following treatment was assessed every day to determine the stage of developmental arrest. Results The median effective concentration to obtain 50% egg mortality (EC 50 ) was 0.5, 0.9, 2.0, 4.8, 5.1 and 9.8% for carvacrol, eugenol, geraniol, citral, terpinen-4-ol and linalool, respectively. The microscopic images of eggs after each treatment indicated that these six terpenes may act by penetrating through the aeropyles on the egg surface. Conclusions In conclusion, carvacrol, eugenol and geraniol possess significant ovicidal activities, which should be considered as promising ovicidal agents for the treatment of scabies. Graphical Abstract
Background
Essential oils may represent an alternative strategy for controlling scabies, a neglected tropical disease caused by the infestation of mite from the species Sarcoptes scabiei . Lemongrass ( Cymbopogen citratus ) oil is reported to possess pharmacological properties including antiparasitc, antioxidant, antimicrobial and anti-inflammatory. The aim of the present study was to assess the potential efficacy of lemongrass oil against the mites and eggs of Sarcoptes scabiei .
Methodology/Principal findings
Mass spectrometry analysis confirmed that the main component presented in lemongrass oil was citral. Lemongrass oil at concentrations of 10% and 5% killed all Sarcoptes mites within 10 and 25 min, respectively. The median lethal concentration value was 1.37%, 1.08%, 0.91%, 0.64%, and 0.48% at 1, 3, 6, 12, and 24 h, respectively. Lemongrass oil at all concentrations (10%, 5%, 1%, 0.5%, 0.1%) was able to significantly decrease the hatching rate of Sarcoptes eggs.
Conclusions/Significance
Lemongrass oil should be considered as a promising miticidal and ovicidal agent for scabies control.
Scabies is a parasitic infestation which affects about 455 million people annually, with a particularly high prevalence in low income tropical regions. The disease is frequently complicated by bacterial infections. Currently available treatments do not meet the ideal profile which includes miticides, ovicidal, antibacterial and anti-inflammatory/antipruritic properties. Cymbopogon citratus is a plant widely cultivated in tropical and subtropical regions. The essential oil from C . citratus is known as lemongrass oil with reported antimicrobial and anti-inflammatory properties. We conducted experiments to assess the miticidal and ovicidal efficacy of lemongrass oil against Sarcoptes mites collected from naturally infected rabbits in China. The results demonstrated that lemongrass oil can kill the motile stages of Sarcoptes mites effectively and presented a significant ovicidal activity. Considering all these properties, lemongrass oil should be considered a promissing miticide against scabies.
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