Gold Standard in Scabies Dr. C Sakthivel. Scabies The ectoparasites, scabies and pediculosis pubis are common causes of skin rash and pruritus worldwide.

Gold Standard in

Scabies

Dr. C Sakthivel

Scabies

• The ectoparasites, scabies and pediculosis pubis are common causes of skin rash and pruritus worldwide.

• Common public health problem in poor communities and developing countries.

• Human scabies – Sarcoptes scabiei

• 30 day life cycle - within the epidermis

• Pregnant female mites burrow into the skin and lay eggs. After two or three days the larvae emerge and dig new burrows. They mature, mate, and repeat this cycle every two weeks.

Scabies

Prevalence

• Scabies and pediculosis are common problem in the society– *Urban slum – 3.5%

• It affects mainly pediatric population – **5.1 % to 22.4%

• Rates of infestation in underdeveloped countries range from 4% to 100%.

• Prevalence is higher in adults who are sexually active.

• Crusted scabies —Norwegian scabies — is found in the– Immunocompromised (HIV), – Decreased sensory function (eg, people with leprosy), – Institutionalized patients.

*Indian Journal of Community Medicine**Vol. 32, No. 1 (2007-01 - 2007-03)Indian Pediatrics 2004; 41:373-377

Life Cycle of Sarcoptes scabiei.

N Engl J Med 2010;362:717-25.

Transmission

• Highly contagious and is spread from person to person by direct skin contact and fomites

• Spread is related to – Overcrowded conditions, – Lack of public awareness – Delayed treatment of primary cases

Symptoms & signs

• Caused by the host immune reaction

• Within two to six weeks of the initial infestation, – reinfestation symptoms within 48 hours.

• Most common lesions – papules, vesicles, pustules, and nodules.

• In adults, – Intractable pruritus, worse at night, – lesions in the web spaces, fingers, flexor surfaces of the wrists, axillae,

and genital areas.

• In infants and young children, – Face, head, neck, scalp, palms, and soles.

Typical childhood scabies – Multiple pruritic papules, vesicles, and pustules. Scabetic burrows are arrowed

Diagnosis• A high index of suspicion

• wide range of symptoms and presentations,. – Adults - rarely on the face and neck– children - commonly on the face and neck

• A history of itching in family members

• Lack of a history of itching in family members does not exclude scabies.

• definitive diagnosis - microscopic – Identification of mites, eggs, or faecal pellets from burrow

scrapings

Treatment

• If scabies is suspected, even without microscopic evidence

• A variety of effective topical medications – permethrin, – malathion, – benzyl benzoate, – Lindane, – crotamiton.

• Children should be given aqueous preparations

• Must be applied correctly to maximise the success

Preferred treatment

• Topical agents such as lindane and permethrin

• Permethrin 5% dermal cream – treatment of choice for scabies

• in the United Kingdom, Australia, and the United States. – Most effective topical agent, acts at all stages of the parasite’s life cycle – Well tolerated, and has low toxicity

• Lindane – Less effective than permethrin – has been withdrawn in many countries

• aplastic anaemia and • potential neurotoxicity.

• Benzyl benzoate – irritant– not recommended for children

J Am Acad Dermatol 2000;42:236-40 BMJ. 2005 May 21; 330(7501): 1194–1198.

* Ivermectin is not approved for this indication by the Food and Drug Administration; there are insufficient data on the safety of ivermectin in pregnancy and in children younger than 5 years of age.

Comparison

*One month after application – Thomson Pharma, 2009

Parameter Permethrin Lindane Crotamiton

safety Safe Safety issues pediatric age

Safety issues in pediatric age

Efficacy Effective than lindane 1% and crotamiton 10%

*Cure rate 98%Cure rate 98%

Effective

*Cure rate 84 %

effective *Cure rate 88%

Comparison of the efficacy of topical 1% lindane vs 5% permethrin in scabies: A randomized, double-blind study

• Resistance to lindane seems to be rising and there are reports of several clusters of patients with lindane-resistant scabies worldwide

• Lindane has limitations for use in children and pregnant women

• Several reports of central nervous system toxicity, convulsions, and even death following accidental ingestion, overuse, or even a single application of lindane

• There is a need for a more effective and safer medication for the treatment of scabies

Indian J Dermatol Venereol Leprol 2006;72:33-6

PermethrinParaciticidal

Mechanism of action

• Acts on the nerve cell membrane to disrupt the sodium channel, and

interrupting signals travelling between the brain and the muscles. The

lice/parasites become paralyzed and die because they are unable to breath.

Permethrin has ovicidal activity and can also kill the nits or eggs of the

parasites.

Pharmacokinetic

• very low dermal absorption and are quickly metabolized to inactive metabolites that are excreted in the urine within a week.

Permethrin cream• Permethrin 5 % cream

• Indication: – For the treatment of infestation with Sarcoptes scabiei (scabies)

• Dosage and administration– Adults and children: Thoroughly massage permethrin cream into the

skin from the head to the soles of the feet. – Scabies rarely infests the scalp of adults, although the hairline, neck,

temple, and forehead may be infested in infants and geriatric patients. – Usually 30 grams is sufficient for an average adult. The cream should

be removed by washing (shower or bath) after 6 to 14 hours. – Infants should be treated on the scalp, temple and forehead.

• ONE APPLICATION IS GENERALLY CURATIVE.

Postscabietic pruritus

• Not uncommon

• last for 2 to 4 weeks after successful treatment

• Attributed to the hypersensitivity response to dead mites and their body parts

• Symptomatic relief– Oral antihistamines – topical corticosteroids– Oral steroids (severe cases)

Key points to reduce transmission

• Fomites, clothes that have been worn the day before treatment and linens ideally should be washed in hot water and dried on high heat.

• All sexual and close personal contacts should be treated even if asymptomatic

• Scabies mite cannot survive longer than 4 days without skin contact; – if hot water is not available, all linen and clothing should be placed into

plastic bags and stored for 5 to 7 days to reduce transmission.

• “Resistant” scabies - due to reinfestation

Review articleClinical manifestations of scabies infection

Lancet Infect Dis 2006; 6:769–79

Review articleScabies: a ubiquitous neglected skin disease

Lancet Infect Dis 2006; 6:769–79

• Children, especially in poor countries, frequently present with scabies superinfected by group A streptococci or Staphylococcus aureus, which should be treated first.

Lancet Infect Dis 2006; 6:769–79

Review articleScabies: a ubiquitous neglected skin disease• Treatment guidelines in early childhood, and during

pregnancy and lactation

USP

• Permethrin cream

– One application is curative

– Safe & effective than lindane

– extremely low mammalian toxicity

– Can be used in all ages

• permethrin is approved for infants 2 months of age or older

– USFDA Approved in 1989

– Combination with ivermectin in crusted scabies

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