6- Dermatology (Skin infections: Viral and infestations) Flashcards
chicken pox background
- Highly infectious disease
- Mostly mild to moderate and self-limiting
o Milder in younger children
o Infection severe in pregnancy- high risk of pneumonia and risk to fetus - Can be dangerous for immunocompromised or older adults
- Endemic in most countries
shingles
Reactivation of dormant virus after bout of chickenpox leads to herpes zoster (Shingles)
o Like chickenpox but confided to just one dermatome
causes of chicken pox
Varicella-Zoster virus (DNA)
Risk factors for chicken pox
- Immunocompromised missed e.g. HIV, children
- Older age
- Steroid use
- Malignancy
transmission of chicken pox
- Transmission- virus enters through upper respiratory tract
- Viraemia occurs 4-6 days later
- Skin lesions last 10-14 days
chicken pox infectivity
Infectivity is from a few days before onset of lesions until the crust falls off
Presentation of chicken pox
- Prodrome- pyrexia, headache and malaise
- Crops of vesicles , mostly on head , neck and trunk, sparse on limbs (new lesions stop after 4 days)
- Papules -> vesicles -> pustules -> crust
- When crust falls off they may leave a mark which will be present for a few weeks (higher risk of scarring in older children )
- Redness around lesion could be bacterial superinfection
management of chickenpox
- Simple advice: fluid intake, minimising scratching, avoid contact with pregnant women and neonates
- Symptomatic treatment – paracetamol (analgeisa and antipyretic), give antihistamine and emollients to help with pruritus
- Do not give NSAIDS (risk of necrotising soft tissue infections)!!!
- Acyclovir not recommended in children
- Encephalitis – admission to hospital
Advice to give parents whos children have chicken pox
- Incubation period of 14-16 days
- Keep child home from school for 5 days
- Infective 24h before and until rash crusts
herpes zoster
shingles
shingles background
- Viral infections, almost always affect the skin of a single dermatome
- Occurs wh›en the host is immunosuppressed- VZV (varicella zoster virus) reactivates and travels through peripheral nerve to skin of single dermatome
pathophysiology of shingles
Virus travels through a cutaneous nerve and remains dormant in dorsal root ganglion after chickenpox
presentation of shingles
- Rash along nerve root
- Painful blisters that scab over
- Itchy, tingly, burning pain
shingles management
Severe e.g. **Hutchinson’s sign **or visual symptoms or serious complication, immunocompromised
- Admit to hospital
- May require aciclovir
Mild
- Analgesia
Prevention of shingles
zoster vaccine (>70-79)
Molluscum contagiosum
Background
- Viral skin infection caused by molluscum contagiosum virus, which is a type of poxvirus
- Spread through direct contact or by sharing towels or bedsheets
presentation of molluscum contagiosum
Presentation
- Small flesh colours papules (raised individual bumps on the skin) that characteristically have a central dimple
- Appear in crops of multiple lesions in a local area
manageemnt of molluscum
Papules resolve by themselves, although this can take up to 18 months.
- Can continue all their normal activities
- Should avoid towel sharing
- Bacterial superinfection may require topical fusidic acid or oral flucloxacillin
Advice
Scratching or picking should be avoided as it can lead to spreading, scarring and infection
management of molluscum if immunocompromised or very extensive lesions
If immunocompromised or very extensive lesions or lesions in genital or eyelids:
- Topical potassium hydroxide, benzoyl peroxide, podophyllotoxin, imiquimod, tretinoin
- Surgical removal and cryotherapy – can lead to scarring
Pityriasis rosea background
Background
- acute, self-limiting rash which tends to affect young adults.
Causes/ risk factors
- The aetiology is not fully understood but is thought that herpes hominis virus 7 (HHV-7) may play a role.