Dermatology - Skin Infections Flashcards
What virus causes chicken pox?
Varicella zoster virus (VZV)
Transmission of VZV?
Highly contagious. Droplet spread or direct skin contact with vesicle fluid, with the virus entering the body via the URT.
Incubation period of VZV?
10-14 days but can be up to 21 days.
What is the contagious period of VZV?
Chickenpox is contagious 1-2 days before rash appears until blisters have scabbed over (5-10 days).
Define a vesicle
Small, raised, fluid-filled lesion
Describe the rash first seen in chickenpox
Chickenpox is an acute disease characterised by a vesicular rash
Prodromal presentation of chickenpox?
- Vesicular rash
- High fever (38-39) – often first symptom
- General malaise
- Anorexia
- Headache
- Nausea
What is a prodrome?
an early symptom indicating the onset of a disease or illness
Describe the progression of the rash in chickenpox
- Begins as small erythematous macules on the scalp, face, trunk, and proximal limbs
- These macules develop into papules, vesicles and pustules which appear in crops
- Crusting of the vesicles and pustules usually occurs after 5 days, at which point new vesicle formation has ceased (no longer contagious after all lesions have crusted over)
General advice for management of chickenpox?
- Hydration
- Avoidance of scratching (keep fingernails short) – due to risk of infection and scarring
- Avoidance of pregnant women, neonates and immunocompromised
What analgesia should be avoided in chickenpox? Why?
NSAIDs → increase the risk of necrotising soft tissue infections
Symptomatic management of chickenpox?
- Paracetamol
- Sedating antihistamines (chlorphenamine)
- Emollients and calamine lotion for itch
- Antivirals → Consider oral acyclovir if adolescent or adult presents within 24 hours of rash onset (especially if severe or at high risk of complications)
What antiviral can be considered in the management of chickenpox?
Aciclovir
Possible complications of chickenpox?
- Bacterial infections of the skin and soft tissues in children, including Group A streptococcal infections.
- Infection of the lungs (pneumonia)
- Infection or swelling of the brain (encephalitis, cerebellar ataxia)
What is Reye’s syndrome?
A rare complication seen in children and young adults recovering from viral illness and thought to be related to aspirin use
What is Reye’s syndrome thought to be related to?
Aspirin use → AVOID in young children
After chickenpox infection, where can the virus lay dormant?
in the sensory dorsal root ganglion cells and cranial nerves
What can chickenpox reactivate later as?
Shingles (Herpes Zoster) or Ramsay Hunt syndrome
What is Ramsay Hunt syndrome?
Ramsay Hunt syndrome occurs when a shingles outbreak affects the facial nerve near one of your ears. In addition to the painful shingles rash, Ramsay Hunt syndrome can cause facial paralysis and hearing loss in the affected ear.
Who does shingles (herpes zoster reactivation) commonly occur in?
Commonly occurs in the elderly and immunosuppressed (shingles in young adults should prompt investigation for an underlying immune condition)
Give some triggers for shingles reactivation
- Nerve pressure
- Radiotherapy at level of nerve root
- Spinal surgery
- Infection
Describe the rash in shingles
- Can manifest first as a tingling sensation severe pain or in a dermatomal distribution
- Progresses to erythematous papules occurring along one or more dermatomes within a few days → develop into fluid-filled vesicles (blistering rash) which then crust over and heal.
What symptoms can accompany the rash in shingles?
May be associated with viral symptoms – fever, headache, malaise, lymphadenopathy in affected area
What is the danger if the trigeminal nerve is affected in shingles?
Ophthalmic shingles
Management of uncomplicated shingles?
- Rest and pain relief
- Protection for rash e.g. Vaseline
- Isolation – infectious to people who have not had chickenpox
When can oral antivirals (aciclovir) be indicated in shingles?
- Oral antivirals if immunosuppressed or if eye involvement
- IV antivirals if severe disease
- Routinely prescribed in people >50
What can ophthalmic shingles lead to?
Corneal ulcers, scarring and blindness if eye involved
What nerve is affected in Ramsay Hunt syndrome?
Facial nerve (VII)
What nerve is affected in ophthalmic shingles?
Trigeminal nerve (V)
What is the most common complication of shingles?
Post-herpetic neuralgia - persistence/re-occurrence of pain in the same area more than 1 month after onset of shingles
What can reduce the chance of post-herpetic neuralgia?
Aciclovir
What is a risk factor for post-herpetic neuralgia?
Age
Facial infections
What are the 2 types of HSV. What infections does each cause?
- Type 1 (HSV1) → oral & facial infections
- Type 2 (HSV2) → genital & rectal infections, often transmitted sexually
BUT either virus can affect other areas of skin/mucous membranes.
Transmission of HSV?
Spread by direct or indirect contact. Virus can be transferred to new skin sites by the patient during an attack.
Is type 1 or type 2 HSV often more symptomatic?
Type 2
What does type 1 HSV mostly present as? What age group?
Gingivostomatitis (gingivitis is inflammation of gums, stomatitis is inflammation of mouth and lips) in children 1-5 y/o:
- Fever
- Restlessness
- Excessive dribbling and bad breath
- Gums are swollen/red/bleeding – eating is painful
- White vesicles → these turn into yellow ulcers on tongue, throat, palate and inside cheeks
- Lymphadenopathy
What does type 2 HSV mostly present as?
- Genital herpes after onset of sexual activity
- Painful vesicles, ulcers, swelling, redness for 2-3 weeks
- In males – glans, foreskin and shaft
- Anal herpes more common in MSM
- Females – vulva and vagina
- Often painful to urinate
- Cervical infection may lead to severe ulcers
What is diagnostic test for HSV?
Swab base of ulcer and send off for nucleic acid amplification tests (NAATs).
Is recurrence of type 1 or 2 HSV more common?
Type 2
What are some triggers for HSV recurrence?
minor trauma, URTAs, sun exposure, hormones (e.g. prior to menstruation), stress
Complications of HSV infection?
- Eye infection – swollen eyelids and conjunctiva
- Throat infection – painful and affects swallowing
- Eczema herpeticum
- Erythema multiforme
- Disseminated/widespread infection – serious in immunocompromised
How can HSV lead to eczema herpeticum?
Occurs when patient with eczema becomes infected by either HSV or VSV through breaks in skin
How does erythema multiforme present?
Targetoid lesions with central blisters
What is the most typical skin manifestation of HIV?
Pruritic papular eruption (PPE)
How does pruritic papular eruption present?
- Itchy
- Discrete scratched red bumps
- Symmetrical
- Diffuse
- Extremities and trunk commonly affected
- No mucosal. palmar or webbing involvement
What are viral warts? What virus are they caused by?
Very common non-cancerous growths.
Human papillomavirus (HPV)
Pathophysiology of warts?
Infection occurs in superficial epidermis, causing keratinocyte proliferation and hyperkeratosis.
Describe the presentation of a viral wart
Hard surface with black dot in the middle of each scale – this is a thrombosed capillary blood vessel
What are plantar warts?
Veruccas - tender, inward growing ‘myrmecia’ with clusters of mosaic warts (less painful)
Topical treatment of warts?
Salicylic acid – removes dead surface cells (keratolytic)
Other treatment options for warts?
- Cryotherapy
- Electrosurgery
What pathogen causes molluscum contagious?
Molluscum contagiosum virus - type of poxvirus
Risk factors for molluscum contagiosum?
- Children <10 y/o
- Warmer climates
- Wet conditions e.g. swimming pool
- Overcrowded environments
- Atopic eczema (deficient skin barrier)
- Immunocompromised
Transmission of molluscum contagiousum?
- Skin-to-skin
- Indirect e.g. towels, bedsheets
- Autoinoculation (shaving or scratching)
- Sexual transmission
Describe the clinical presentation of molluscum contagiosum
- Clusters of small (1-6mm), round papules (raised bumps) – can be few to 100s in a local area
- White, pink or brown (fresh coloured)
- Often shiny with umbilicated pit
- Papules contain white, cheesy material
- Arise in warm/moist places e.g. flexures