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52 CPD ACTIVITY FROM PAGE 51 parents to a laboratory for identification were commonly found to be artefacts such as dandruff, hairspray droplets, scabs, dirt, or other insects. Head lice control Public health strategies are based on limited research and little is known about transmission dynamics. Mismanagement and transmission in the general community are blamed for control failure. Shampoos Several OTC and prescription medications exist for the treatment of head lice infestation. Permethrin (a synthetic pyrethroid) has been the most studied pediculicide and is the least toxic to humans. Traditional head lice treatments include a wide variety of neurotoxins, including organochlorines (lindane), organophosphates (malathion), carbamates (carbaryl), pyrethrins and pyrethroids (permethrin, D-phenothrin).10 However, these have failed to achieve adequate control. Moreover, their repeated use, residual nature and misapplication has led to the selection of resistant populations of lice in Australia.11 To treat infestation, the product is applied to damp hair, which is first shampooed with a non-conditioning shampoo and towel dried. The treatment is left on for 10 minutes and rinsed off. Permethrin leaves a residue on the hair that is designed to kill nymphs (lice that have hatched but not yet reached adult stage). However, this is inhibited by conditioners and silicone-based shampoo additives. Conditioner should therefore be avoided during treatment with permethrin products. Experts commonly recommend routine retreatment, preferably on day nine, to complete the full life cycle of the parasite.12 Combing Mechanical treatment options have gained in popularity out of concern about pesticide toxicity and resistance, and partly as a cost control measure. A small observational survey of Belgian children treated at home found that 47 per cent (18 of 38) of parents who opted to wet comb using conditioning creme rinse were successful, compared with 56 per cent (14 of 25) who chose to use insecticides. A combination of the two methods proved effective in only 37 per cent (seven of 19).13 Recent Australian work shows that head lice treatment containing Australian eucalyptus oil and lemon scented tea tree oil (Leptospermum petersonii) (EO/LP) solution has been shown to be safe and effective.7 The small failure rate reported was possibly due to louse eggs surviving on the scalp, but it was most likely due to reinfestation. The fact that the EO/ LP solution is both volatile and quickly effective may mean it’s unlikely to cause rapid development of resistance. Human body lice Body lice (Pediculus humanus humanus, sometimes called Pediculus humanus corporis) usually infest people living in unhygienic, crowded conditions who are unable to bathe or change clothes regularly. In Australia, body lice infestation is uncommon in the homeless population.14 The nits are found in the seams of human clothing. Body lice has been reported to transmit bacterial diseases such as trench fever, typhus and louse-borne relapsing fever in places where war, poverty, and unsanitary conditions exist. Their bites cause intense irritation, itching and allergies. Chronic infestation can cause skin thickening and discoloration. Body lice are typically passed by close contact with an infected person or contaminated clothing. Good hygiene and regular washing of clothing and bedding will prevent infestation. Chemical pediculicides provide effective treatment for body lice infestations. Pubic lice Infestation by Phthirus pubis (pubic or crab lice) is called phthiriasis. It may be considered a sexually transmitted illness, therefore the general perception that phthiriasis is a sign of poor hygiene may not be accurate. Lice are spread by sexual transmission – close contact with an affected person or with objects they have very recently contacted, such as bedding, clothing, combs and brushes. The parasite usually prefers sites where the distance between adjacent hairs is equivalent to its grasping span, particularly preferring pubic hair, but also axillary, chest, beard hair, and eyelashes.3 Pubic lice lay eggs on the hair shafts. The nits are firmly adherent and resist both mechanical and chemical removal. Lice can survive in soap and water for protracted periods. Pubic lice infestation affects all socioeconomic groups, but the incidence appears to be persistent in vulnerable populations, possibly due to insecticide resistance, reliance on physical methods of removal which are not very effective, and increased sexual activity in the adolescent population. Children with pubic lice have usually been infected through contact with an adult. Phthiriasis in children may suggest possible child abuse and should be investigated. A major concern in treating pubic lice is the lack of appreciation for their tendency to also reside in rectal hairs. Further to treatment with topical preparations, patients must be instructed to liberally treat the groin and rectal regions, otherwise treatment failure may occur.16 Lice don’t survive unless they have ready access to human blood, so some people will choose to shave their pubic hair off completely to remove the infestation. Some dermatologists prefer to treat pubic lice using ivermectin as their first- line therapy.15 Scabies Infestation with Sarcoptic scabiei (called scabies in man and mange in animals) is a common, highly contagious skin disease. Its common name, the ‘‘itch mite’’ is derived from the severe pruritis it causes.17 Scabies occurs across Australia but most frequently in clusters in settings with higher population density, including residential aged care facilities, prisons, refugee camps, among returned travellers from endemic areas, and within remote Aboriginal and Torres Strait Islander communities with overcrowded housing.18 The mite is transmitted via person-to- person contact. Therefore, household contacts are at highest risk of infestation. Only 20 minutes of close contact (eg, holding hands or sexual contact) is required for successful transmission.19 Clinical features An asymptomatic carrier state may initially occur. A primary symptom is generalised pruritus, which is most intense at night.20 The symptoms of scabies infestation are caused by the hosts’ allergic response to the mite. Pruritus in a neonate unable to scratch may manifest as irritability, insomnia and poor feeding. Skin findings include a generalised erythematous vesiculopapular eruption, with lesions commonly concentrated in the web spaces of the fingers and toes, wrists, buttocks, breasts, genitals and sometimes scalp.19 Mite burrows and excoriation from scratching result in coexisting bacterial infection in up to 79 per cent of studies.21 Mites probably pose the greatest health hazard, not only because they are the most common inhabitants in number and variety RETAIL PHARMACY • JAN/FEB 2021