DR. MD. ABDAL MIAHASSISTANT PROFESSORDERMATOLOGY & VENEREOLOGYMYMENSINGH MEDICAL COLLEGE, MYMENSINGH
DR. MD. SHAHAB UDDIN AHMED CHOWDHURYAssociate Professor & HeadDepartment of Dermatology & VenereologyMymensingh Medical College, Mymensingh.
TODYS TOPIC ISIVERMECTINUSE IN SCABIES Source:American Family Physician (Review Journal)Sept 15, 2003, V-68, P-1089-92
Scabies is a skin disease caused by infestation with the mite female gravid sarcoptes scabiei var hominis. Scabies has been a problem for humans since before the first millennium and was reported by the earliest writers who described mankinads health problems. It is estimated that there may be 300106 cases of scabies worldwide each year. Mostly, scabies is treated with topical scabicides, which needs to be used over whole or nearly whole skin surface, which is a difficult process.INTRODUCTION
So, non compliance or improper use of topical scabicides can result in scabies as a public health problem. So, the time honored demand was for systemic alternative. Now, oral ivermectin has appeared as an effective and cost-comparable alternative to topical agents in the treatment of scabies infection.
DIAGNOSIS OF SCABIES The diagnosis of scabies usually is clinical but may be confirmed by microscopic identification of female mite, eggs and scybala in skin scrapings.Key points for the diagnosis of scabies are the following:
1.Morphology of skin lesions (i.e. type of eruptions)Pathognomonic lesion Linear burrows.Nonspecific-Papular or papulovesicular or vesiculo-pustular lesions.Excoriations and ulcerations.Urticarial lesions- rarely.
2.Typical distributionCommon sites (irrespective of age and sex).Finger-webs, flexor surfaces of wrists, flexor surfaces of elbows, axillae, umbilicus, waistband, gluteal crease.Male-genitaliaFemale-breasts (Areola and Nipple) Infants and young children-Scalp, face, palms and soles
3.Pruritus Usually intense, disproportionate to the amount of eruptions, worse at night and pleasant in quality.4.Positive history in skin contacts.5.Definitive diagnosis rests on identification of the mites or its products.Useful diagnostic methods:a)Direct examination of skin scrapings under low power objective.b)Dermoscopy.c)PCR.
TREATMENT A.Treatment of patients: It includesi)Treatment of complicationsii)Symptomatic treatment andiii)Specific treatment with scabicides.
Topical and systemic scabicides:a.Topical scabicides includePrecipitated sulfur 6% or 7% in petroleum jellyBenzyl benzoate emulsion 25%Monosulfiram- a 25% solution1% Gamma benzene hexachloride (lindane)Malathion 0.5%Crotamiton 10%b.Systemic scabicide- oral ivermectin 200 gm/kg- Single dose, may have to be repeated.
B.Treatment of contacts.C.Trcatment of house-hold utensils.
IVERMECTIN First it was developed in the 1970s as a veterinary treatment for animal parasites.It is a member of a family of macrolytic lactones, the avermectins.It has broad spectrum activity against parasites such as
FDA approved-StrongyloidiasisOnchocerciasis.Not FDA approved-FilariasisCutaneous larva migrans.Scabies.Pediculosis etc.An estimated 6 million people world-wide have taken ivermectin for various parasitic infestations.
Since 1993, it has been successfully used in different countries to treat human scabies that is resistant to treatment.Some of the study results are shown below:
StudyNo. of patientsCured (%)Not Cured (%)12696.153.852111000031008317411 (with AIDS)70*>90**30*
Many other studies done by different groups such as Glaziou P et al, Dunne CL et al, Kar SK et al, Shouela EN et al, Madan V et al, Usha V et al also confirmed the efficiency of ivermectin as a treatment of scabies infection.
SAFETY OF IVERMECTIN:Adverse effects such as anorexia, nausea, vomiting, rash, headache, dizziness, arthralgia, itching, eosinophilia, abdominal pain, fever, tachycardia etc may occur but occur very infrequently. No serious drug-related adverse events or significant drug interactions have been reported.But its safety in young children and pregnant women not established.
A comparison of ivermectin with 5% permethrin is shown below:
DrugEfficacyAdverse effectsCostUse in childrenIn pregnancyNursing womenIvermectin83-100%anorexia, nausea, vomiting, rash, headache, dizziness, arthralgia, itching, eosinophilia, abdominal pain, fever, tachycardia etc Tk. 40*Tk. 80**Safety not proved in children
Superiority of ivermectin over others:1.Easy route of administration oral.2.Dose convenience only single dose.3.Efficacy very high- 98-100%.4.Safe very infrequent side effects and not a single major adverse event over 6 million users.5.Cost effective.
So, many authors and publications consider it to be the treatment of choice.
CONCLUSION Oral ivermectin, because of its single oral dosing, very high efficacy and safety, and low cost, may replace the other topical agents in the treatment of scabies. It may be particularly useful in the treatment of severely crusted scabies lesions in immunocompromised patients or when topical therapy has failed or application of topical agents is logistically difficult (e.g. large institutional outbreaks or mentally impaired patients).
MESSAGE We know the causeWe know the mode of transmissionWe have multiple weapons to fight against this mite.But this mite is winning the battle affecting 300 million peoples each year around the globe.
So, IVERMECTIN may be the best weaponto win this battle.