Makindo Medical Notes

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

About

• Herpes viruses are double-stranded DNA viruses.
• Spread is by droplet transmission and is highly contagious.
• Most people acquire immunity in childhood, providing some degree of protection.
• It can flare up later in life, typically manifesting as shingles.
• Has a propensity for affecting the skin, eyes, and nervous system.

Virology

• Varicella - Chickenpox; Zoster - Shingles.
• Incubation period is 10-21 days.
• The virus resides in the dorsal root ganglion and cranial nerve nuclei.

Shingles - Belt-like rash on one side

Severe, extensive, or prolonged disease may suggest underlying immunosuppression, such as HIV. Chickenpox can be caught from shingles, but not vice versa.

Clinical Presentation

• Chickenpox is usually seen in children without prior immunity.
• Adults have a higher morbidity and mortality rate (15x higher than children).
• Pregnant women are particularly vulnerable to varicella pneumonitis.
• Fever, malaise, and maculopapular lesions on the face are common.
• Successive crops of macules, papules, and vesicles appear with fever.
• Pneumonitis presents with dyspnea, fever, cough, and calcification on CXR.
• Encephalitis presents with headache, obtundation, and has a 20% fatality rate, often with massive brain oedema.
• Cerebellitis is transient in children and usually resolves.
• Hepatitis and thrombocytopenic purpura are additional complications.

Other Manifestations

• Shingles: the virus resides in the dorsal root ganglion. Elderly and immunocompromised individuals are at higher risk. Pain precedes the appearance of a vesicular rash, usually affecting a single dermatome.
• Postherpetic neuralgia can be severe, often in the lumbar or thoracic dermatome.
• Herpes Zoster Ophthalmicus: affects the cornea and the ophthalmic branch of the trigeminal nerve.
• Ramsay Hunt syndrome: VII palsy with vesicles in the external auditory meatus, resembling Bell's palsy.
• Transverse myelitis, Guillain-Barre syndrome, and acute retinal necrosis are other possible complications.
• Stroke syndromes: Infection can cause granulomatous arteritis of the cerebral arteries.

Risks of Varicella Pneumonia

• Cigarette smoking
• Pregnancy
• Immunosuppression
• Male sex

Immunocompromised

• A more severe and widespread form of shingles is seen in immunocompromised people. The rash may affect multiple dermatomes or last longer.
• High-risk patients include:
  • HIV with low CD4 counts
  • Bone marrow or solid organ transplant recipients
  • People on steroids, azathioprine, mercaptopurine, or TNF antagonists
  • Patients with underlying malignancy
  • Pregnancy

Investigations

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

Management

• Prevention is best; the national campaign recommends vaccination for all people over 65 to prevent shingles and postherpetic neuralgia.
• Consult with a specialist to determine whether to stop immunosuppressants or steroids based on risk vs. benefit.
• Isolate the patient if admission is required, allowing only those with immunity to chickenpox to provide care.
• Oral antiviral treatment should be started within 72 hours of rash onset for:
  • People with immunocompromise, localized rash, or non-severe systemic symptoms.
  • Patients with non-truncal involvement (e.g., neck, limbs, perineum).
  • Those with moderate to severe pain or rash.
• Consider oral antiviral treatment within 72 hours for people over 50 to reduce postherpetic neuralgia.
• Even if it's after 72 hours, consider treatment if vesicle formation continues or for high-risk patients (e.g., older, immunocompromised, or in severe pain).
• If a pregnant or breastfeeding woman has shingles, seek specialist advice before prescribing antivirals.
• In immunocompetent children, antiviral treatment is usually not necessary.
• Postherpetic neuralgia may require treatment with amitriptyline, gabapentin, or capsaicin cream.

Choice of Antivirals for Shingles: (Check BNF for renal disease adjustments)

• For immunocompetent adults:
  • Aciclovir: 800 mg 5 times daily for 7 days.
  • Famciclovir: 500 mg TDS for 7 days.
  • Valaciclovir: 1000 mg TDS for 7 days.
• For immunocompromised adults:
  • Aciclovir: 800 mg 5 times daily for 7 days, continue for 2 days after lesions crust.
  • Famciclovir: 500 mg TDS for 10 days, continue for 2 days after lesions crust.
  • Valaciclovir: 1000 mg TDS for 7 days, continue for 2 days after lesions crust.

Prevention of Chickenpox in Pregnant or Immunocompromised People Exposed to Virus

• Most adults are immune, but a live attenuated vaccine is available for healthcare workers.
• If a non-immune pregnant or immunocompromised person is exposed to varicella or shingles, administer Zoster immunoglobulin (ZIG) within 10 days of exposure.
• If they develop chickenpox, treat with Aciclovir. Contact a Consultant Microbiologist for advice.

Postherpetic Neuralgia

• Chronic pain following shingles, characterized by burning pain, allodynia (pain from a non-painful stimulus), hyperalgesia, and intense itching.
• Risk increases with age, severity of acute shingles pain, and prodromal symptoms.
• Treatment options include paracetamol, codeine, amitriptyline, gabapentin, or duloxetine. Capsaicin cream and lidocaine plasters can also be used.
• Tramadol may be used as acute rescue therapy but should not be prescribed long-term without specialist supervision.

References

• Shingles NICE Guidance (November 2019)