Herpes Zoster or Shingles (Viral Skin Infection)

Question 1

Background

Answer 1

Shingles (herpes zoster) is a viral infection of an individual nerve and the skin surface that is served by the nerve (dermatome). It is caused by the reactivation of the varicella-zoster virus, the virus which causes chicken pox.

More common in adults, especially the elderly, sick or immune-suppressed

Question 2

Signs and Symptoms / Diagnosis

Answer 2

Pain, in the areas of sensory nerves emerging from the spine.

The patient feels quite unwell with fever, headache and regional lymphadenopathy (enlarged lymph node/s).
Within 1-3 days of the onset of pain, crops of closely grouped erythematous papules develop within the unilateral dermatome(s). New papules continue to appear for several days, each blistering or becoming pustular then crusting over.

Diagnosis:
History taking, find risk factors and examine (symptoms etc)

Question 3

Treatment

Answer 3

Uncomplicated recovery is in 2 to 3 weeks. Elderly 3 to 4 weeks.

Management includes rest, applying povidone iodine to blisters, oral aciclovir and steroids for severe cases and oral antibiotics for secondary infection.
If they get Post-herpetic neuralgia (pain persisting for >90 days after rash onset) they need analgesia.

CKS:
Management
Oral antiviral - aciclovir, valaciclovir, or famciclovir.
Prescribe within 72 hrs of rash if immunocompromised or non truncal or moderate/severe - pain or rash.

Doses (extra)
immunocompetent adults: (7 day courses)
Aciclovir: 800 mg 5/day 4-hourly intervals.
Famciclovir: 500 mg TDS, or 750 mg 1–2/day
Valaciclovir: 1000 mg TDS.
Immunocompromised same doses but F only 500mg option and 10 day course. All to be continued 2 days after lesions crusted.

Pain - Mild:
- ibuprofen.
Not effective, or SEVERE pain, consider amitriptyline (off-label use), duloxetine (off-label use), gabapentin, or pregabalin.
Consider oral corticosteroids in the first 2 weeks following rash onset in immunocompetent adults with localized shingles if pain is severe, but only in combination with antiviral treatment.
children with pain,offer a trial of paracetamol.

Prevention
2-dose Shingrix® vaccine
Give to >60 in 2 stages and >70 with 26-52 week gap. Offered if severity of disease is higher or at risk of post herpetic neuralgia.

Question 4

Drug info

Answer 4

Oral antiviral:
If swallowing is difficult can try dispersible form, need to stay hydrated, use analgesics to reduce pain, wash hands with soap after touching lesions.
F - efficacy decreased in severe hepatic impairment.
AE - GI effects, skin rashes, V - neurological disorders.
Key interactions- Aminophylline and theophylline — aciclovir valaciclovir may increase the plasma concentration of aminophylline and theophylline

Vaccine:
- Zostvax:
Contraindicated - immunosuppressive therapy (high dose oral steroid), Untreated TB, P,
AE - injection site reactions.
- Shingrex:
AE - injection site reactions.