Viral herpes Flashcards
What is the pathophysiology of herpes virus?
Once infected, it hides in a latent/resting state in the spinal dorsal root nerves
In recurrence or reactivation –> virus travels along the nerves to the skin or mucous mem where it multiplies and causes blisters
After re-activation –> will return to resting state
What are the signs and symptoms of herpes virus?
Localised blistering
Oral and facial lesions
Genital and rectal infections
What strain of herpes primarily causes genital herpes?
HSV2
genital and rectal
What strain of herpes primarily causes herpes simplex? (Cold sores)
cold sores = HSV1
Oral and facial
What strain of herpes primarily causes chicken pox?
varicella-zoster virus
How does the chicken pox illness progress?
Prodromal phase of 1-2 days (fever, lethargy, cold-like sx) –> itchy pink papules appear –> papules develop into small fluid-filled blisters
Blisters break and crust –> infection resolves and lays dormant in dorsal root ganglia
What are some triggers for reactivation of HSV1 and HSV2?
Minor skin trauma
Upper resp tract infection
Sun, cold, or wind exposure
Hormonal factors (e.g. menstruation)
Emotional stress
What are some triggers for herpes zoster reactivation?
Age >50
Medical condition that suppress the immune system (e.g. cancer, HIV, transplant recipient
Immunosuppressant medication
How do you differentially diagnose varicella and other viral infections and dermatitis?
Varicella will have papules or vesicles
Explain some differential diagnoses for HSV1/2/varicella
Insect bites = don’t present in crops or groups, hx important
Drug eruption = eruption tends to be uniform, chickenpox is crops
Angular cheilitis = common in denture wearers, painful and moist, fissure at corner of mouth
Impetigo/bact infection = similar on face to shingles, shingles is painful and will form in belt (this wont), can spread to area beyond lip
Allergic contact dermatitis = unlikely to be vesicular, can correspond to allergen contact, hx important
Generally, how can a simple cold sore be treated?
Mild uncomplicated eruption generally not need tx
Prevent or avoid trigger
Blister can be covered (hydrocolloid patch)
Topical antiviral or oral antiviral may be desired
Single oral dose tx has similar efficacy to topical but may be more convenient
Start oral therapy during prodromal period
What are some non-script tx for simple cold sores?
Aciclovir 5% crms = every 4hrs for 4-5 days
Penciclovir 1% crm = every 2 hours while awake for 4 days
*Above tx only reduce pain and duration by 1.5 days
Aciclovir + hydrocortisone cream = 5*/day for 5 days
(of little benefit) Idoxuridine w/ lidocaine - every hr while awake and then every 4hrs until cleared
Famciclovir tablet (1*1500mg tablet)
How is the initial infection of genital herpes treated?
Antiviral drugs for sx
Untreated will last up to 3 wks
How is episodic genital herpes treated?
Mild recurrence = no tx
May treat w/ antiviral for shorter course - treat asap, preferably in prodromal period
How is severe recurrence of genital herpes treated?
Require repeated course or continuous prophylaxis tx for several months+
What are the available oral antiviral drugs?
Aciclovir
Famciclovir
Valaciclovir
How is herpes varicella treated in healthy children?
Non-pharm tx
Trim nails - minimise scratching
Adequate fluid intake to avoid dehydration
Lukewarm bath may help and apply moisturiser
Paracetamol for discomfort/fever
Topical anti-itch - pine tar lotion
Amorphous hydrogel for healing and hydration
How are children with pre-existing skin disease treated when they develop chicken pox?
Require antiviral meds (e.g. aciclovir) to reduce risk of severe disease or complication
How are adults and immunocompromised people treated when they get chicken pox?
They’re at greater risk of severe disease and complications –> antivirals recommended
Tx choice depends on:
- duration of rash
- rash severity
- whether complications are already present
How are immunocompetent patients treated for shingles?
W/in 72hrs of sx onset
Famciclovir 500mg, q8h for 7 days
Valaciclovir 1q q8h for 7 days
Aciclovir 800mg 5/day for 7 days
How are immunocompromised patients w/ shingles treated?
W/out disseminated diseaes:
- Regardless of sx duration, treat w/ antivirals
- Same regimen/drugs/dose as w/ immunocompetent patient
w/ disseminated disease = hospital admission –> IV antivirals
What is the general/sx tx for shingles?
Rest and pain relief
Acute neuropathic pain –> ice packs and paracetamol, topical therapies (lidocaine, capsaicin)
Severe pain = oral steroids or opioids (Dont)
Post herpetic neuralgia = adjuvants like - gabapentinoids, TCA, SNRIs
Protective ointments (vaseline) may be applied to rash
What are some referral points for herpes infections?
Doubt over diagnosis
Suspect shingles (Esp in elderly), severe sx or evident secondary infection
Suspect chickenpox in neonate/adult due to inc risk of severe disease and complications - early systemic meds indicated for adults
Suspect herpetic neuralgia - more difficult/ complex to treat
suspect herpes zoster affecting eye, medical emergency
What is the best preventer against chicken pox?
vaccination
