Makindo Medical Notes.com

Related Subjects: |Herpes Varicella-Zoster (Shingles) Infection |Chickenpox Varicella Infection |Varicella Cerebral Vasculopathy |Analgesia and Pain management |Sedation and Analgesia on ITU |Neuropathic Pain Management

National campaign recommends vaccination in all of those over 70 to prevent shingles and postherpetic neuralgia. Also see the topic on Herpes Zoster Ophthalmicus for those with eye involvement and on Chickenpox

About

• Herpes Viruses and so double-stranded DNA
• Spread is by droplet and highly contagious
• Mostly acquired in childhood with some degree of protection
• It can flare up later in life
• Propensity for the skin, eye and nervous system

Virology

• Varicella - Chicken pox, Zoster - Shingles
• Incubation period 10-21 days
• Virus exists in dorsal root ganglion and cranial nerve nuclei

Shingles belt like rash on one side

Severe, extensive or prolonged disease suggests underlying immunosuppression, e.g. HIV. Chickenpox may be caught from shingles but not vice versa.

Clinical

• Chickenpox is usually seen in children who lack immunity
• Adults have increased morbidity and mortality (x15)
• Pregnant are particularly vulnerable to pneumonitis
• Fever, malaise, maculopapular lesions on the face
• Successive crops of Macules, papules, vesicles with fever
• Pneumonitis presents with dyspnoea, fever, cough and calcification on CXR
• Encephalitis - headache, obtunded 20% fatal with massive brain oedema
• Encephalitis - Cerebellitis - transient findings in children which usually resolves
• Hepatitis, Thrombocytopenic purpura

Other manifestations

• Shingles - the virus is resident in the dorsal root ganglion. Elderly and the immunocompromised at risk. Pain precedes a rash which is vesicular and painful. >Post herpetic neuralgia can be severe. Usually in the distribution of lumbar or thoracic dermatome but can involve lower limb. The ophthalmic branch of the Trigeminal nerve can affect the cornea.
• Ramsay Hunt syndrome with VII palsy and vesicles in external auditory meatus - resembles a Bell's palsy
• Transverse myelitis, Guillan-Barre syndrome
• See topic of Herpes Zoster ophthalmicus
• Stroke syndromes - infection can cause granulomatous arteritis secondary to infection of cerebral arteries.
• Acute retinal necrosis (ARN) may be due to the virus

Risks of Varicella Pneumonia

• Cigarette smoking, Pregnancy
• Immunosuppression, Male sex

Immunocompromised

• A more severe and widespread form of shingles is seen in immunocompromised people, rash may be severe, long-lasting, or affect multiple dermatomes.
• High risk patients
  • HIV with low CD4
  • Bone marrow or solid organ transplant
  • Steroids, Azathioprine, Mercaptopurine etc.
  • Tumour necrosis factor (TNF) antagonists
  • Underlying Malignancy
  • Pregnancy

Investigations

• FBC, U&E, LFTs, CRP and look for clinical evidence of immune impairment? cancer red flags
• Vesicle fluid can be examined by electron microscopy or DNA PCR and Florescent antibody staining

Management

• Prevention is best and the national campaign recommends vaccination in all of those over 65 to prevent shingles and postherpetic neuralgia
• Take expert advice on stopping immunosuppressants or steroids based on risks vs benefits. If admission needed then isolate so that only those with immunity to chickenpox with antibodies are involved with care. Overall recovery may take several months
• Prescribe an oral antiviral treatment within 72 hours of rash onset for people with any of the following criteria
  • Immunocompromise (if the level of immunocompromise is not severe, the rash is localized, the person is not systemically unwell, and they can be closely followed up).
  • Non-truncal involvement (such as shingles affecting the neck, limbs, or perineum).
  • Moderate or severe pain. Moderate or severe rash
• Consider prescribing oral antiviral treatment within 72 hours of rash onset for all people aged over 50 years to reduce the incidence of post-herpetic neuralgia, which is most common in this age group.
• If it is not possible to initiate treatment within 72 hours, consider starting antiviral treatment up to one week after rash onset, especially if the person is at higher risk of severe shingles or complications (for example continued vesicle formation, older age, immunocompromised, or in severe pain).
• If a pregnant or breastfeeding woman has shingles, seek specialist advice before prescribing antiviral treatment.
• For immunocompetent children with shingles, antiviral treatment is not usually recommended.
• Consider oral corticosteroids in the first 2 weeks following rash onset in immunocompetent adults with localized shingles if the pain is severe, but only in combination with antiviral treatment.
• Postherpetic neuralgia may require Amitriptyline or Gabapentin. Capsaicin cream has also been useful.
• Ramsay Hunt syndrome (Herpes zoster oticus): resembles Bell's palsy but there are vesicles in the meatus. Treat with Famciclovir.
• The rash can develop a secondary bacterial infection and the patient may require Benzylpenicillin and Flucloxacillin

Choice of Antivirals for Shingles: See BNF for renal disease

• For immunocompetent adults:
  • Aciclovir: 800 mg x 5/day for 7 days at 4-hourly intervals, omitting the night time dose.
  • Famciclovir: 500 mg TDS for 7 days, or 750 mg 1-2 times a day for 7 days.
  • Valaciclovir: 1000 mg TDS a day for 7 days.
• For immunocompromised adults (if they are not systemically unwell and the rash is localized):
  • Aciclovir: 800 mg x 5/day for 7 days. Continue for 2 days after the lesions have crusted.
  • Famciclovir: 500 mg TDS for 10 days. Continue for 2 days after the lesions have crusted.
  • Valaciclovir: 1000 mg TDS a day for 7 days. Continue for 2 days after the lesions have crusted.

Prevention of Chicken Pox in Pregnant or Immunocompromised in those exposed

• Most adults are immune. A live attenuated vaccine is available. Useful for healthcare workers. Exposure of Pregnant, on steroids, the immunosuppressed patient is non-immune and in contact with varicella or shingles, they will require ZIG (Zoster immunoglobulin) within the first 10 days of exposure. Give Aciclovir if they develop chickenpox. Contact Consultant Microbiologist for advice.

Post herpetic Neuralgia

• Chronic pain associated with shingles. Can be constant or intermittent stabbing or burning pain, allodynia (pain induced by a non-painful stimulus), hyperalgesia (severe pain from a mildly painful stimulus), and intense itching.
• Risk of post-herpetic neuralgia increases with age, presence and severity of prodromal pain, and severity of acute shingles pain.
• Symptoms can resolve after a few months, or may persist for longer. Interventions may not completely resolve the pain but may reduce it. Initial treatment with paracetamol should be offered, either alone or in combination with codeine. Drugs used to treat neuropathic pain may also be prescribed.
• A person with post-herpetic neuralgia should be advised to: Wear loose clothing or cotton fabrics, as these will usually cause the least irritation. Consider protecting sensitive areas by applying a protective layer (such as cling film or a plastic wound dressing). Consider the frequent application of cold packs (unless allodynia is triggered by cold).
• Referral to a specialist pain clinic or a relevant clinical speciality (such as neurology) is advised if any of the following apply: The person has severe pain. Their pain significantly limits their daily activities and participation. Their underlying health condition has deteriorated.
• Medications
  • Paracetamol +/- Codeine
  • Amitriptyline
  • Duloxetine
  • Gabapentin
  • Pregabalin
• Topics
  • Capsacin cream
  • Lidocaine plasters
• Tramadol may be considered if acute rescue therapy is required, but should not be prescribed long-term without specialist supervision.

References

• Shingles NICE guidance November 2019