Page 55 - Demo

of species, but because they also readily transmit agents from almost every major group of pathogens: bacteria, chlamydia, rickettsia, viruses, protozoa, spirochetes and helminths.22 Diagnosis Diagnosis is often based on clinical recognition of a rash in a typical distribution (the interdigital spaces and limb extremities in older children and adults, as well as palms, soles and scalp in infants and older people). Diagnosis can be more challenging in cases that don’t have a typical distribution or appearance. It’s crucial to consider other differential diagnoses that may mimic classical scabies, including insect bites, other infections and inflammatory or immune- mediated dermatological conditions. A response to empirical treatment also supports the scabies diagnosis. General principles of management Delay between infestation and symptoms in the index case results in asymptomatic infested household contacts at the time of first diagnosis. Therefore, it’s important to also treat household contacts in all cases. The risk of reinfestation is high if contacts are not treated.23 Once scabies treatment has begun, it’s common for the itch to increase over a few days. It’s important to advise patients about this, to avoid the perception of treatment failure. The itching associated with scabies infestation can be managed with moisturisers, mild topical corticosteroids, or oral antihistamines. If scabies treatment has been successful, all symptoms, including the itch, will generally resolve by four weeks. Intensively pruritic, persistent nodules occasionally occur for months after successful treatment, most likely representing a hypersensitivity reaction to retained mite antigens.24 Treatment options for scabies The treatment of choice for neonatal Table 1. Scabies treatment options scabies is permethrin 5% cream. It’s approved for use in infants as young as two months old, with one report of safety and efficacy in a 23-day-old infant. Efficacy is superior to that of lindane, crotamiton, benzyl benzoate and sulphur. Critical to success is the simultaneous treatment of all close contacts, even if asymptomatic. Mild corticosteroid cream (eg, 1% hydrocortisone) may help control the residual pruritus and dermatitis that can persist for several weeks following eradication. Ivermectin has been used orally in cases of refractory scabies in adults. Table 1 provides a summary of treatment options for classical scabies. INTESTINAL WORMS Endoparasites considered in this section include soil-transmitted helminthiasis (STH) infections that have been described globally. These parasites live in the gut and can invade other organs. They are passed on via soil contaminated with eggs or when an infected child scratches their bottom and doesn’t wash their hands. They can then ingest the eggs or leave them on surfaces or bed clothes where the eggs can survive for up to two weeks. As the prevalence and intensity of infection peaks in school aged children, this group have traditionally been the priority for treatment. As soon as an infant begins to explore their environment and encounter contaminated soil, they are at risk of infection according to the levels of transmission in the local area.25 Only a few STHs are prevalent in the Oceania region (Australia, New Zealand, Melanesia and the Polynesian and Micronesian islands of the Pacific). STH of public health significance in this region include:26 • Threadworm (Enterobius vermicularis). • Hookworm (Ancylostoma duodenale). • Ascariasis (Ascaris lumbricoides). • Whipworm (Trichuris trichiura). CPD ACTIVITY 53 • Roundworm (Strongyloides stercoralis). • Tapeworm (Taenia solium – pork tapeworm, or Taenia saginata – beef tapeworm). • Dwarf tapeworm – hymenolepiasis (Hymenolepis nana). Threadworm is the most common STH infection throughout Australia. Hookworm infection is possibly the most prevalent STH in Aboriginal communities in northern Australia.27 It’s found almost exclusively in Western Australia and the Northern Territory where A. duodenale is believed to be the sole species.28 It’s believed that mass treatment during the Australian hookworm campaign of 1919–1924 reduced the hookworm prevalence among communities in that region.27 Ascariasis and whipworm are much less common in Oceania. However, whipworm appears to be a common geohelminth in Fiji, accounting for almost half the number of cases in Oceania. Large numbers of cases also appear in the Solomon Islands and Vanuatu.29 Sporadic cases reported in Australia have a history of recent travel. Roundworm is an important soil- transmitted helminth infection in Oceania, although no overall prevalence data is available.30 The high rates of roundworm infection among Aboriginal populations may partly reflect a high incidence of human T-cell lymphotropic virus type 1 (HTLV-1) infection, which predisposes to this parasite. Prevalence rates of roundworm infection as high as 60 per cent have been reported in central Australia among Aboriginal people.28 Hymenolepiasis infection has been reported as a common soil-transmitted cestodiasis among indigenous communities in Australia and Papua New Guinea,31 although the overall prevalence is not known. Mass drug administration with albendazole was found to be ineffective at reducing the prevalence of this parasite in the Northern Territory.27 Diagnosis In community settings the diagnosis of STH is made through clinical features including patient history. Children who can communicate well often complain of an itchy bottom, while less developed children may be restless at night or generally irritable. The diagnosis is confirmed either by detecting parasites in the faeces or nappy, or by detecting an antibody response to the parasite in the serum. Symptoms are related to the number of worms present in the bowel. They are generally mild (or absent) in low level TO PAGE 54 Age Medication Comment First line From <2 months of age Crotamiton 10% Repeat daily for three days Efficacy questionable From >2 months of age Permethrin 5% Treatment of choice Can repeat after 7–14 days if ongoing symptoms Second line >6 months of age Benzyl benzoate 25% Repeat once after 7–14 days Third line >5 years of age Ivermectin* Adult, child >15 kg, oral 200mcg/kg as a single dose, repeated on days 8-15; a third dose on day 2 is given in severe cases *Category B3 in pregnancy (increased incidence of congenital malformations in mice and rats), risk/benefit consideration in breast feeding. RETAIL PHARMACY • JAN/FEB 2021