Varicella Zoster - Herpes Viruses

Varicella Zoster

·        Primary infection: Chicken Pox. 

o   Macules ® papules ® vesicles ® crusts

o   Incubation 10 – 21 days (usually 14 – 16)

o   Infectious for 1 – 2 days before rash appears until it crusts over

o   Highly infectious, in hospital requires strict respiratory/contact isolation

o   Complications: 

§  Commonly becomes super-infected (eg with scratching) with Staph aureus (or S Pyogenes) which leads to scarring 

§  If immunocompromised ® overwhelming infection, pneumonitis, hepatitis, encephalitis (treat with Ig and acyclovir) 

§  Post-natal infection can be overwhelming 

§  Immune response can ® encephalopathy with cerebellar ataxia

§  Can lead to severe exacerbation of eczema

o   Then remains dormant in dorsal root ganglia

o   Treatment: Supportive, antipruritic lotion if itchy, cut fingernails short 

o   Prevention: Live attenuated virus, or im Ig within 96 hours of exposure if at risk and susceptible (immunocompromised, pregnant, newborn, prem babies)

·        Tests: culture – swab transported in viral medium

·        Vaccination:

o   Live attenuated vaccine recently licensed for both children and adults

o   Not recommended for general use, but role in protecting non-immune adults (more severe illness)

o   Contra-indicated if immuno-suppressed or pregnant

Shingles: 

o   Reactivation of infection: affects 20% at some time. Elderly and immunocompromised are high

·        Symptoms: Dermatomal pain, then fever malaise for several days, then macule-papules + vesicles, especially in thoracic or ophthalmic division of trigeminal dermatomes. If sacral, then urinary retention may occur. Thoracic (50%), cervical (20%), trigeminal (15%)

·        Complications: 

o   If shingles around eye (especially end of nose), then are likely to have a dendritic ulcer on cornea. Stain with Fluorescein and shine on blue light, corneal abrasions will shine green. Don‟t give steroid ® blindness. Urgent referral to an ophthalmologist.

o   Post-hepatic neuralgia – especially in the elderly and trigeminal

o   Recurrence rare and suggests HIV (or Dermatomal Herpes Simplex)

·        Treatment if needed: acyclovir as early as possible, 800mg 5 times a day for 5 days. Pain relief – analgesic or low-dose amitriptyline. Maybe prednisolone to reduce post-herpetic neuralgia. Report visual loss immediately