Scabies and dematocytosis

Definition of Scabies
• Scabies: A parasitic infection of the skin characterised by an intense itching with typical distribution caused by the mite Sarcoptes scabei

Epidemiology of Scabies
• Scabies is common in rural Africa
• Prevalence is high in areas with shortage of water and is uncommon in people who bathe regularly
• Low socio-economic conditions favour the spread of the disease

• Transmission is by direct close body contact from infected person and indirectly through bedclothes and clothing
• The female mite enters the skin and makes a small tunnel or burrow
• The burrow is always superficial
• The skin selected for burrow is always thin and wrinkled giving scabies rash a typical distribution
• In the burrows, eggs and faeces are produced
• The eggs hatch in 4-5 days
• The larvae leave the parent tunnel and bury in the skin in other places, but they do not make tunnels

Clinical Features and Diagnosis of Scabies
Clinical Features
• Intensive itching, especially at night
• Eczema-like signs
o The itching leading to scratching
o Secondary bacterial infection
• In case of immunosuppression such as HIV and AIDS, infestation can be extensive
• Typical distribution of severe itch and rash are:
o Anterior axillary fold
o Nipples, lower abdomen in women
o Belt line (umbilicus)
o Front side of wrist and elbows
o External genitalia
o Thighs and buttocks
o Sides of fingers and toes
o Sides and webs of fingers
o Scalp and feet (affected only in infants under 1 year)
• Due to secondary bacterial infection scabies can complicate to:
o Septicaemia
o Glomerulonephritis
o Rheumatic fever
• Patients with leprosy or other diseases which interfere with normal sensation may not feel the itching caused by scabies. In these cases, scabies can be very extensive and thick crusts can form.

Diagnosis
• Based on clinical findings
o Pruritus and symmetric polymorphic skin lesions
o Presence of burrows
• Microscopic examination of scrapings for:
o Mites
o Eggs
o Faecal Pellets

Treatment of Scabies
• The drug of choice is 10% Benzyl benzoate Emulsion (BBE)
• After the patient has taken a warm bath, the drug is applied over the whole body except the face
• After 24 hours of first treatment, the patient should bath again and put on clean clothes
• The drug has no effect on the eggs, therefore repeat BBE after 4 – 7 days to kill those larvae which have hatched since the first treatment
Other Drugs
• Drugs which can be used in the absence of BBE include:
o Tetmosol solution or soap (but not always available)
o Permethrin cream 5% (applied to areas of the body from neck downward and washed off after 8-14 hours)
o Ivermectin 200µg/kg orally and repeated after 2 weeks
o Lindane (1%) lotion or cream
       Applied in a thin layer to all areas of the body from the neck down and thoroughly washed off after 8 hours
     However is not recommended as first line drug because of toxicity
      It should only be used if the patient cannot tolerate other drugs or if other drugs have failed to heal the patient
      It is contraindicated in pregnant or lactating women and children aged less than 2 years
o Antibiotics are used only when there is a secondary infection (preferably Penicillins)

Other Management Considerations
• Decontamination of bedding materials and clothing
• Wash in hot water and aired or removed from body contact for at least 72 hours
• Treat the whole family
• The itching will not disappear immediately, if necessary treat it symptomatically with calamine lotion
• The treatment should not be repeated so soon in infant
• The scalp should also be treated for scabies but remember to protect the eyes carefully

Prevention and Control of Scabies
• Regular bathing with soap
• Washing of clothes and frequent use of soap will control the disease
• Give health education to stress the use of soap
• Treat the whole family.

Dermatomycosis
• Dermatomycosis: A term applied to fungal infection of the skin and its appendages e.g. hair and nails
o Several types are identified according to causative organism, site and clinical
appearance.
o They are sometimes indicators of immunosuppression as occurs in AIDS, cancer, diabetes and tuberculosis.

Mode of Transmission of Dermatomycosis
• All fungi may be transmitted to humans by direct skin contact from their habitat in the soil, vegetation, animals or other individuals.
• Genital infection (balanitis and vulvo-vaginitis) may spread during sexual intercourse but most candida infections are not sexually transmitted.
• Local conditions on the skin such as moist and hot environment are predisposing factors and therefore the infections are highly prevalent in tropical climates.

Types of Dermatomycosis
• Tinea capitis (ringworm of the scalp)
• Tinea corporis (ringworm of the body)
• Tinea pedis (Ringworm of the foot or ‘athlete’s foot’)
• Tinea unguium (Ringworm of the nails)
• Tinea versicolor or pityriasis

Clinical Features of Different Dermatomycosis

Tinea Capitis (Ringworm of the Scalp)
• Begins as a small papule which spreads to involve a larger area.
• Hairs in the affected skin become brittle and break off easily.
• It occurs mainly in children under 10 years and often disappears after puberty.

Tinea Corporis (Ringworm of the body)
• This is characterised by flat ring shaped spreading lesions.
• The ring lesions are reddish, vesicular or pastula, and may be dry and scaly, or moist and crusted.
• The central area often clears leaving apparently normal skin.
Tinea Pedis (Ringworm of the foot or athlete’s foot)
• Characterised by scaling and cracking of the skin between the toes, particularly the fourth and fifth toes.

Tinea Unguium (Ringworm of the nails)
• This is characterised by a thickening, discolouration and brittleness of the nails.
• There is accumulation of caseous materials beneath the nail which becomes chalky and disintegrates.

Tinea Versicolor or Pityriasis
• This is a very superficial infection.
• Skin on side of face, neck and chest show many irregular, round and light-coloured areas.

Diagnosis of Dermatomycosis

• Clinical diagnosis is unreliable
• Confirmed by laboratory investigations
o Microscopic examination of scrapings after KOH preparation
o Results - branching filaments crossing borders of cells are seen
• The technique is easy and materials needed are simple to collect

Treatment
Tinea Capitis
• Griseofulvin is the drug of choice, although oral therapy with itraconazole and terbinafine are effective alternatives.
• Oral fluconazole seems to have similar efficacy to Griseofulvin
• Give Griseofulvin at a dosage of 250mg twice a day or 500mg once a day in adults and 20-25mg/kg for children for 6-12 weeks
• Whitefield’s ointment applied twice daily for 3 – 6 weeks has also been used in areas where the above drugs are not available.

Tinea Corporis
• This responds well with topical application of topical antifungals such as Clotrimazole 1% cream, lotion or solution (use twice daily), and Ketoconazole 2% cream (used once daily).
• Severe disease and disease in immunocompromised patients should be treated with systemic agents.

Tinea Cruris
• Topical antifungal treatment should be used (just as in tinea corporis)
• Resistant lesions can be treated with Griseofulvin or other systemic agents.
• Patients should be advised to dry the area completely after bath and not to wear tight clothing

Tinea Pedis
• Topical agents applied for duration of 4 weeks are usually effective.
• Chronic or extensive disease may require
o Griseofulvin 250 – 500mg twice daily for 6 – 12 weeks, or
o Terbinafine 250mg daily, or
o Itraconazole 200mg daily

Tinea Unguium
• Systemic antifungal are indicated.
• Terbinafine and itraconazole have been show to be more effective than other agents.

Dermatomycosis Prevention and Control
• Early diagnosis and treatment of infected person.
• Improve personal hygiene – regular bathing with water and soap
• Dry skin well (especially feet)