Musculoskeletal Disorders and Psychosocial Factors in the Workplace View project MD research project "Social exclusion as consequence of illness: stigma and everyday life in a former leprosy colony in Northeast Brazil View project

Because topical compounds based on insecticidal chemicals are the mainstay of head lice treatment, but resistance is increasing, alternatives, such as herbs and oils are being sold to treat head lice. To test a commercial shampoo based on seed extract of Azadirachta indica (neem tree) for its in vitro effect, head lice (n=17) were collected from school children in Australia and immersed in Wash-Away LouseTM shampoo (Alpha-Biocare GmbH, Germany). Vitality was evaluated for more than 3 h by examination under a dissecting microscope. Positive and negative controls were a commercially available head lice treatment containing permethrin 1% (n=19) and no treatment (n=14). All lice treated with the neem shampoo did not show any vital signs from the initial examination after immersion at 5–30 min; after 3 h, only a single louse showed minor signs of life, indicated by gut movements, a mortality of 94%. In the permethrin group, mortality was 20% at 5 min, 50% at 15 min, and 74% after 3 h. All 14 head lice of the negative control group survived during the observation period. Our data show that Wash-Away LouseTM is highly effective in vitro against head lice. The neem shampoo was more effective than the permethrinbased product. We speculate that complex plant-based compounds will replace the well-defined chemical pediculicides if resistance to the commonly used products further increases. Introduction Prevalence of head lice (caused by infection with Pediculus capitis) has been increasing worldwide (Burgess 2004). Topical insecticides based on insecticidal chemicals are still the mainstay of head lice treatment (Heukelbach and Feldmeier 2004), and resistance to the common over-thecounter pediculicides has been reported repeatedly by clinicians and confirmed by in vitro studies (Burkhart et al. 1998; Burkhart and Burkhart 2006; Downs et al. 2002; Elston 2003; Hunter and Barker 2003; Mumcuoglu et al. 1995; Picollo et al. 2000; Yoon et al. 2003). Resistance is particularly frequent in countries where head lice are common and where chemical insecticides are extensively used, such as in the US, UK, Israel, and Australia. Because the prevalence and degree of insecticide resistance is expected to increase, alternative topical therapies for head lice infestations are needed. We tested the shampoo “Wash-Away LouseTM” based on seeds of Azadirachta indica (neem tree) for its effect on head lice in vitro. The results show that the product is highly effective against P. capitis. Materials and methods Head lice were collected from two school children and their mothers in Townsville, Australia on two occasions separated by a month. After collection, lice were pooled and held on human hair in 5 cm diameter plastic Petri dishes at 27°C and 50% relative humidity. In vitro tests were started within 1 h after collection of lice, or when this was not possible, lice were fed on the dorsum of the hand of one of the investigators and used for testing within 1 h after feeding. A commercially available head lice shampoo based on extracts of neem seeds (Wash-Away LouseTM; AlphaBiocare GmbH, Düsseldorf, Germany) was tested. Wash-Away LouseTM contains a patented oily extract from seeds of the plant A. indica, formulated with the following cosmetic ingredients: distilled water, polylgyceryl-3J. Heukelbach . F. A. S. Oliveira Department of Community Health, School of Medicine, Federal University of Ceará, Fortaleza, Brazil J. Heukelbach . R. Speare School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Townsville, Australia J. Heukelbach (*) Departamento de Saúde Comunitária, Faculdade de Medicina, Universidade Federal do Ceará, Rua Prof. Costa Mendes 1608, 5. andar, Fortaleza, CE 60430-140, Brazil e-mail: [email protected] caprate, cocamidoprophybetaine, glycerol, lauryl glucoside, dicaprylyl ether, and as preservation components benzyl alcohol, benzoic acid, and sorbic acid. As a positive control, a 1%-permethrin-based over-thecounter compound was used (Quellada Head Lice Treatment, Glaxo Smith Kline). For the tests, lice clasping hair strands were immersed completely in the product for 1 min, then placed with hairs onto Whatman filter paper in Petri dishes. To prevent lice from desiccation, the filter paper had been previously moistened by 200 μl tap water. After lice were placed on the filter paper, obvious pools of the liquid product rests adherent to the body of lice were wiped from the lice by a jeweller’s forceps directed under a dissecting microscope. Negative control lice were placed directly on the filter paper without any treatment. To simulate treatment on an infested host, head lice were washed in tap water after 20 min and placed into a new Petri dish. The number of lice was 17, 19, and 14 in the neem group, the permethrin group, and the control group, respectively. Lice were tested in batches of seven to 14 and the results were then pooled. Lice on the filter paper were examined under a dissecting microscope by a single observer in all cases to prevent interobserver variation. The criteria used for survival of lice were extremely strict: if any even minor signs of life, such as internal movements, or movements of antennae or minimal leg movements were observed (with or without stimulation by a forceps), the lice were categorized as alive. The lice were judged as dead if there were no vital signs at all (complete physical death). These data were compared to the usual criteria for “mortality”: the inability to walk in a progressive fashion or no righting reflex when rolled onto the back (Hunter and Barker 2003; Mougabure et al. 2002). Examinations were performed after 5, 10, 15, 20, 30, 45, 60, 90, and 180 min. All lice were maintained at 27°C during the tests.