Lice, Foot Care, and Warts

• Miscellaneous Derm 2 covers lice, foot care, and warts

Lice

• Lice are parasites that consume human blood and require a human host to live and reproduce
• Pediculosis is an infestation of lice
• Pediculicides are medications that treat lice
• There are three types of lice: head lice (pediculus humanus capitis), body lice (pediculus humanus corporis), and pubic lice

Comparing Lice Types

• Head lice transmission: via children, head-to-head contact, and occasionally objects
• Body lice transmission: typically occurs among individuals with poor hygiene, through clothing and bedding
• Pubic lice transmission: occurs via sexually active individuals through close contact and sharing bedding
• Head lice nits: are less than 1 mm in length and yellow-brown
• Body lice nits: are less than 1 mm in length and grey-white
• Head Lice: takes 6-10 days to hatch and ~2 weeks to adulthood. Adults live up to host for 30 days and females lay 5-10 eggs per day
• Body Lice: takes 6-10 days to hatch and ~2 weeks to adulthood. Adults live up to host for 30 days and females lay 5-10 eggs per day
• Pubic Lice: takes 6-10 days to hatch and ~2 weeks to adulthood. Adults live up to host for 30 days and females lay 5-10 eggs per day
• Head lice survival: Nits live up to 30 days away from the host, but require warmth to hatch, while lice survive for 1-2 days
• Body lice survival: Nits live up to 30 days away from the host, but require warmth to hatch, while lice survive for 1-2 days
• Pubic lice survival: Nits live up to 30 days away from the host, but require warmth to hatch, while lice survive for 1-2 days
• Lice saliva and feces can cause a hypersensitivity reaction that leads to itch
• Head Lice location: scalp, particularly behind ears and nape of neck; nits within 6 mm of scalp
• Body lice location: along clothing seams and close to warm body areas
• Pubic lice location: typically pubic hair and nits at the base of hair shaft

Presentation of Lice

• Lice infestations are often asymptomatic
• Louse saliva and feces can cause a hypersensitivity reaction and itch
• Secondary symptoms of lice: crust, excoriations, pustules, and infection
• Nits are usually close to the scalp, less than 1 cm is viable
• Commonly found behind ears and at back of scalp

Goals of Therapy for Lice

• The primary goals of lice therapy are to exterminate lice, relieve pruritus, prevent spread and reinfestation, prevent secondary bacterial infection, and prevent/alleviate psychosocial effects

Managing Lice Infestation

• Identify and assess close contacts and treat when necessary
• It is of the utmost importance in managing infestations
• Laundering items in hot water and with a hot dryer treats personal items and the home environment
• Storing items in a sealed plastic bag for 2 weeks will kill the lice
• Soak brushes in hot water for 10 minutes
• Thorough vacuuming of bedding, furniture, and carpet
• Non-pharmacologic therapy is sufficient for body lice

Wet Combing

• Wet combing is also known as bug busting or nitpicking and is a method for detection and mechanical removal
• Wet combing can replace pharmacologic therapy
• Should be done after treatment to remove nits
• Live lice must be detected to confirm infestation
• A metal lice comb, light, and magnifying glass should be used
• The lice comb should have 0.2-0.3 mm spacing of teeth
• The comb must contact the scalp
• Can be done with water, oils, or white conditioner

Discouraged Approaches for Lice

• Petroleum jelly, mayonnaise and WD-40 are not recommended
• "Zappers" are not recommended
• No-nit policies are not recommended and children should return to school after lice treatment

Pharmacologic Treatment Options

• Neurotoxic Insecticides include Permethrin 1% (Nix, Kwellada) and Pyrethrins + piperonyl butoxide (R&C)
• Physical Agents include Dimethicone 50% (NYDA) and Isopropyl myristate/Cyclomethicone (Resultz)
• All four have similar efficacy

Neurotoxic Insecticides

• Cause respiratory paralysis of the louse by disrupting action potentials at voltage-gated sodium channels
• Cure rate is up to 97% and ovicidal activity is much lower and retreat in 7-10 days
• Permethrin 1% and pyrethrins/piperonyl butoxide are also indicated for pubic lice
• Permethrin 1% ADRs is mild and transient itching, redness, swelling, burning, stinging, rash, tingling, and numbness
• Pyrethrins/piperonyl butoxide 0.33%/0.3% (R&C) is contact dermatitis from solvents in the formula
• Permethrin 1% contraindications: Chrysanthemum allergy?
• pyrethrins/piperonyl butoxide contraindications: Chrysanthemum/ragweed allergies
• Permethrin 1% is the first choice for most patients
• Both Permethrin 1% and pyrethrins/piperonyl butoxide are safe for pregnancy, lactation, and everyone 2 months of age
• Itching post-treatment is not indicative of failure

Physical Agents

• Dimethicone 50% (NYDA) penetrates spiracles of the louse causing suffocation
• Dimethicone 50% (NYDA) up to 97% cure rate, up to 100% ovicidal, and Itching/eye irritation
• Isopropyl Myristate / Cyclomethicone (Resultz) dissolves the exoskeleton causing dehydration and death
• Isopropyl Myristate / Cyclomethicone (Resultz) ~60-90% cure rate, not ovicidal, and Local irritation/pruritis
• Dimethicone 50% (NYDA) and Isopropyl Myristate / Cyclomethicone (Resultz) are only indicated in children 2; no data for pregnancy & lactation
• Benzyl alcohol 5% lotion is non-ovicidal and not yet marketed in Canada

Factors in treating lice

• Cost
• Ease of Administration
• Resistance
• Other patient factors such as length of hair

A very handy table – Rx files

• Permethrin Hair starts: towel-dried (shampoo first), Apply: 25-50mL, Leave in for: 10 min, Rinse with water Nitpick +/- comb, Repeat in 9 days
• Pyrethrins/ piperonyl butoxide Hair starts: dry, Apply: ≥25mL, Leave in for: 10 min, Wash out with regular shampoo next a.m. Nitpick +/- comb, Repeat in 9 days
• Isopropyl Myristate Hair starts: dry, Apply: 30-120mL, Leave in for: 10 min, Wash out with regular shampoo next a.m. Nitpick +/- comb, Repeat in 9 days
• Dimethicone Hair starts: dry, Apply: 10-34mL, Leave in for: After 30 min comb out nits, then leave for 8 more hrs, Wash out with regular shampoo next a.m. Nitpick +/- comb, Repeat in 9 days

Treatment Failure in Lice

• Potential causes of treatment failure: misdiagnosis, improper application of product, removal of nits, not repeating treatment properly/at all, reinfestation, resistance
• Examine causes for failure
• Switch classes
• Permethrin 5% cream overnight (not officially indicated)
• Oral Ivermectin
• Oral sulfamethoxazole-trimethoprim

NHPs & Adjunct Agents for Lice

• Some evidence for star anise oil
• Insufficient evidence to recommend anything else
• Consider cultural safety when making recommendations,
• Natural is not harmless and can cause Contact dermatitis and Prepubertal gynecomastia
• Adjunct Agents: Antihistamines and topical corticosteroids

Monitoring Lice Treatments

• Monitor to remove live lice 24 hours post-treatment to prevent resistance in 7-10 days
• Nitpick with a comb to remove the nits and use vinegar to condition them
• Administer antihistamines and topical corticosteroids, and for infection; use topical or systemic antibiotics to treat
• Clear of inflammatory pustules; return to normal skin appearance within 1 week

Foot Care: Corns, Calluses & Bunions

• Foot care consists of covering corns, calluses, and bunions

Corns & Calluses

• Thick skin
• Excessive friction causes the skin to protect itself by growing thicker leading to hyperkeratotic tissue
• Most common cause is poorly fitting footwear
• Females > males

Differentiation of Corns and Calluses

• Corns usually occur on the top of the foot/toe
• Calluses usually occur on the sole of the foot, especially the ball or heel area
• Corns consist of thickened, deep skin with tough layers of compacted, dead skin
• Calluses consist of skin is flat and widespread
• Corns may have a radix central cone
• Calluses do not have a radix, and the thickness is even
• Calluses tend to be less sensitive than surrounding tissue

Bunions (hallux valgus)

• Bunions: deformity of the 1st metatarsophalangeal joint
• Bunions are typically acquired, sometimes structural
• Pain is the predominant symptom
• Signs: bump, swelling, erythema
• May develop calluses and bursitis
• Bunions affect foot function and the ability to wear shoes
• Bunionettes(Taylor's bunion) are thought to be inherited

Footwear Assessment

• Assess corns, calluses & bunions
• Table 1: Footwear Suitability Assessment in CPS chapter outlines some principles for assessment
• Consider a referral to footcare specialists such as a Podiatrist, Pedorthist, Occupational therapist, Physiotherapist, etc.

Nonpharmacologic Treatment for Foot Problems

• Refer if Diabetic, PVD, Immunocompromised, >65
• Identify and remove cause -usually footwear! May add orthotics if indicated
• Recommend regular self or professional foot exams.
• Soak (+/-baking soda)x 10min, then debride with pumice stone, or use a file on dry foot. Can apply oils to soften skin. Professional Escision
• Surgery

Pharmacologic Treatment for Foot Problems

• Maintain moisture balance and remove dead skin
• Corns /Calluses
• Salicylic acid (keratolytic) up to 40%
• Plasters/pads over liquids
• Bunions
• Pain relief measures (ice packs, analgesics)
• Intra-articular corticosteroids in extreme cases

Cutaneous Warts

• Can be common, flat, and plantar

Pathophysiology, Etiology, Epidemiology of Warts

• HPV infection leads to replication in the epithelium tissue leading to growth and benign tumor
• Contagious through direct or indirect contact with broken skin
• Most common in children and young adults

No Warts

• Exposure → Incubation time between 1-9 months in skin → virus remains latent → No warts

Appear Warts

• Exposure → Incubation time between 1-9 months in skin → virus NOT cleared→ Warts

Clinical Presentation for Warts

• Generally asymptomatic, abnormal-appearing skin growth

Clinical Types for Warts

• Common
• Hands/nails, sites of trauma
• Skin-colored or grey-brown papule. Single or grouped. Studded with black dots
• Usually none. May cause pain/bleed if irritated.

Management

• Most warts self-resolve within 6 months – 5 years (if immunocompetent), so watchful waiting is an option
• Remove the wart/virus, prevent spread/recurrence, Maintain healthy surrounding tissue, Alleviate symptoms (i.e, pain, if present), Restore/improve normal cosmetic appearance

Management Continued

Refer if warts are widespread or on face/genital area, diagnosis is uncertain, treatment fails, or patient has neuropathy/circulatory disorder

Non-Pharmacologic Therapy for Warts

• Duct tape (occlusion therapy): Insufficient Evidence
• Laser therapy: Comparable Cryotherapy
• Surgical Removal: Painful Acupuncture: Difficult to Draw conclusions
• Herbal Remedies: Insufficient Evidence

Pharmacologic Therapy: Salicylic Acid (SA)

• 1st line therapy MOA: KereatolyticEfficacy:~50-75% clearanceADRs: redness, irritation, macerationCannot be used by patients with diabetes, impaired circulation, neuropathy, etc.Cannot use on the faceRequires consistent, daily application for 12+ weeks. Patient education: Soaking (warm water), file with pumice stone, healthy tissue

Cryotherapy

• Line; efficacy ≈ salicyclic acid
• More adverse effects: pain, blistering, pigment -changes.
• May require anesthetic -Can add SA between treatments to ⇧ efficacy -Typically takes as long as SA, with treatments ~q2 weeks -Liquid nitrogen applied by a HCP reaches -196°Chome application kits (dimethyl ther + propane) reach -57°C

Other Pharmacologic Options

• 5-fluourouracil 5% cream daily x Insufficient Evidence:
• CimetidineOther Limited /Inconsistent evidence
• HPV vaccine (prevention): Cantharidin/podophyllin/SA

Monitoring

• Size should improve within 2-3 weeks. Refer if no reduction in 12 weeks, or if increasing in size despite treatment.Colour, Shape should not change for the worse; refer if so