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HEAD LICE, SCABIES AND WORMS CPD ACTIVITY 51 Dr Moses Mutie BVM, MPharm (Rch), Grad Dip (HealthSt), PhD LEARNING OBJECTIVES After completing this CPD activity, pharmacists should be able to: • Describethesymptomsandsigns of head lice, scabies and intestinal worms and how they are spread between people. • Describethepharmacologicalandnon- pharmacological treatment options for head lice, scabies and intestinal worms. • Adviseparentsandcarershowto prevent spread of head lice, scabies and intestinal worms from the child to close contacts. 2016 Competency Standards: 3.2, 3.6 Accreditation Number: A2102RP1 (exp: 31/01/2023). Introduction With the school year beginning, pharmacy staff are likely to be asked about the treatment of common infestations affecting children. Many different products are available. Parents tend to rely on marketing information to self-select therapies. However, efficacy differs between products. Recent reviews have indicated the substantial lack of evidence on the efficacy and safety of traditional and alternative treatments, with most of the limited randomised controlled trials found to be of low validity.1 Review by the TGA found clinical trials conducted on the effectiveness of head lice treatments were complicated by inconsistencies and methodological flaws.2 This high- level summary is divided into two parts. Part one reviews the common ectoparasitic infestations (pediculosis and scabies) while part 2 reviews endoparasites (soil-transmitted helminthiasis) which are common problems for parents with children of pre-school and school age. LICE AND SCABIES Ectoparasitoses (infestations with parasites that live on or in the skin) cause considerable morbidity. Their prevalence in the general population are usually low but can be higher in vulnerable groups. Recent evidence on how best to manage parasitic skin diseases in different settings is scant, and practical measures for control are outdated or unavailable.3 For head lice (Pediculus humanus capitis) and scabies (Sarcoptes scabiei), the situation is daunting, because resistance to insecticides is reported to spread rapidly.4 General characteristics of ectoparasitic diseases Ectoparasitic diseases share many of the general characteristics of emerging infectious diseases.5 Commonly shared characteristics include the following: • Origination as zoonoses (from animal to human), with disease establishment dependent on arthropod vector competency (vector’s ability to transmit disease). • Introduction into new, susceptible host populations. • Infection by endemic agents given selective advantages by changing ecologic or socioeconomic conditions. • Recent travel from rural to urban endemic areas, often following migrating human host populations seeking better economic opportunities. Pediculosis: general comment Pediculosis refers to infestation of blood-sucking lice that have long been successful obligate parasites (cannot complete its lifecycle without a suitable host). Three types of lice infest humans: • Head louse (Pediculus humanus capitis). • Body louse (Pediculus humanus corporis). • Pubic louse (Phthirus pubis). Louse infestation presents with pruritus, excoriations, and lymphadenopathy. A hypersensitivity rash (pediculid) may mimic an eruptive viral skin rash (exanthem). Hunter and Barker6 reported different patterns of resistance in Brisbane school aged children, including full resistance to malathion, permethrin and pyrethrum in two schools, but susceptibility to malathion and, to a lesser extent, pyrethrums in three others. The increasingly poor performance of neurotoxic head lice treatments and the growing public concern over their use has led to an increase in the commercialisation of alternative treatments, many of which are poorly researched or even untested.7 Although pediculosis is not a major health problem, it can be the cause of social embarrassment, isolation, anxiety, peer criticism, unnecessary absenteeism from school and work, and generally a difficult problem to solve. Head lice Head lice infestation crosses all economic and social boundaries, creating social, economic and health consequences.8 Problems with self-detection, chronic infestations and classroom transmission are compounded by increasing resistance to pediculicides. Transmission in most cases occurs by direct contact with the head of an infested individual. Head lice move by grasping hairs, generally remaining close to the scalp. The head louse is the size of a sesame seed (1-2mm), has six legs and is usually tan to greyish white in colour. Head lice can crawl rapidly, up to 23cm/min. After attaching to the patient, the louse inserts its mouth parts into the skin and injects saliva, which has vasodilatory properties. An inflammatory reaction to the saliva has been suggested as the most likely cause of bite reactions. Lice egg cases are referred to as nits. They are firmly cemented to the base of human hairs and are thus difficult to remove. School aged children (three to 14 years) are most commonly affected. Evidence indicates that classrooms are a main source of infestation.9 Queensland evidence indicated that lice are most likely to rely on head-to-head transfer and that environmental (classroom, carpets, furniture) transmission is less likely.10 The main symptoms associated with infestation include itching and discomfort. Gold standard for diagnosis is to find a live louse on the head, which can be difficult since lice avoid light exposure and can crawl quickly. Louse combs increase the chances of finding live lice. Nits alone are not diagnostic of active infestation, but if the nits are within 1cm of the scalp, active infestation is likely. Head lice and nits are commonly misdiagnosed. Hair casts (pseudonits – collections of scalp epidermal cells around the hair root) may closely resemble nits and are misdiagnosed as active infestation. Parents, teachers or school nurses generally notice these and mistake them for nits. Hair casts are freely movable along the length of the hair shaft, while nits are firmly cemented. Presumed ‘lice’ and ‘nits’ submitted by GPs, nurses, teachers and TO PAGE 52 RETAIL PHARMACY • JAN/FEB 2021 2 CPD CREDITS