What do I need to know about herpes zoster?

Herpes Zoster: Essential Clinical Knowledge

Clinical Presentation

Herpes zoster typically presents with prodromal pain 24-72 hours before a unilateral vesicular eruption in a dermatomal distribution, with lesions progressing from erythematous macules to papules to vesicles over 4-6 days in immunocompetent patients. 1

Classic Features

• Prodromal pain precedes skin findings by 24-72 hours in most cases 1, 2
• Unilateral dermatomal distribution is the hallmark finding 1, 2
• Vesicular progression: erythematous macules → papules → vesicles over 4-6 days 1
• Total disease duration approximately 2 weeks in healthy individuals 1
• Trigeminal or ophthalmic involvement causes more severe pain 1

Atypical Presentations

• Nonspecific lesions without classic vesicular appearance initially 1, 2
• Faint, evanescent, or localized rash 1
• Difficult to recognize in darker skin pigmentation 1
• Zoster sine herpete: pain without rash or late-onset rash, associated with diagnostic delays and increased mortality 1
• Immunocompromised patients may have prolonged eruption periods and slower healing 2

High-Risk Populations

Immunocompromised Patients

• Blood, bone marrow, or solid organ transplant recipients are at significantly higher risk 1
• May develop chronic ulcerations with persistent viral replication 1
• Secondary bacterial and fungal superinfections are common complications 1
• Require laboratory confirmation for atypical presentations 2

Diagnosis

Clinical Diagnosis

• Clinical diagnosis alone is sufficient for typical presentations in immunocompetent patients 1, 2
• Laboratory confirmation required for immunocompromised patients or atypical presentations 2

Diagnostic Testing

• Tzanck smear showing giant cells indicates herpesvirus infection 1
• Vesicle fluid specimens for immunofluorescence antigen testing, culture, or PCR to confirm diagnosis 1
• Viral shedding peaks in the first 24 hours after lesion onset when most lesions are vesicular 3

Treatment

Antiviral Therapy - Immunocompetent Patients

For uncomplicated herpes zoster, oral valacyclovir or acyclovir should be initiated within 72 hours of rash onset and continued until all lesions have scabbed. 3, 4, 5

First-Line Oral Antivirals

• Valacyclovir 1 gram three times daily for 7 days (preferred due to better bioavailability and less frequent dosing) 3, 2, 6
• Acyclovir 800 mg five times daily for 7-10 days (alternative option) 3, 2, 4
• Famciclovir (similar efficacy with better bioavailability) 3, 5, 6

Treatment Timing

• Initiate within 72 hours of rash onset to reduce severity, duration of eruptive phase, and acute pain intensity 4, 5, 7
• No data on treatment initiated >72 hours after zoster rash onset 4
• Treatment should be started as soon as possible after diagnosis 4

Treatment Duration

• Continue until all lesions have scabbed 3, 4

Antiviral Therapy - Immunocompromised Patients

High-dose intravenous acyclovir is the treatment of choice for severely immunocompromised hosts with disseminated or invasive herpes zoster. 1, 3

• IV acyclovir for disseminated or invasive disease 3
• Temporary reduction in immunosuppressive medication should be considered 3
• Oral antiviral therapy can be used for mild cases in patients with transient immune suppression 1
• Kidney transplant recipients with uncomplicated disease: oral acyclovir or valacyclovir 3

Treatment Caveats

• Topical antiviral therapy is substantially less effective than systemic therapy and is not recommended 3
• Antivirals do not eradicate latent virus but control symptoms and reduce complications 3
• Adequate hydration should be maintained during treatment 4
• Dosage adjustment required for patients with renal impairment 4

Adjunctive Therapies

• Analgesics for acute zoster pain control 5
• Good skin care for healing and prevention of secondary bacterial infection 5
• Prednisone may be used as adjunctive therapy in select cases of severe, widespread disease, but carries significant risks in elderly patients 3
• Prednisone should be avoided in immunocompromised patients due to increased risk of disseminated infection 3

Facial Herpes Zoster

• Elevation of affected area to promote drainage of edema 3
• Keep skin well hydrated with emollients to avoid dryness and cracking 3
• Particular attention required due to risk of cranial nerve involvement 3

Complications

Postherpetic Neuralgia (PHN)

• Most common and debilitating complication of herpes zoster 5, 8
• Significant adverse effects on quality of life and activities of daily living 8
• Varicella-zoster virus vaccine and early treatment with famciclovir or valacyclovir are the only proven preventive measures 5

PHN Treatment Options

• Topical agents: lidocaine patches 5
• Systemic agents: gabapentin and pregabalin 5
• Treatment is only modestly successful with significant side effects 8

Other Complications

• Secondary bacterial infections 1
• Central nervous system involvement (requires laboratory testing) 5
• Higher mortality rate in immunocompromised individuals 5

Prevention

Vaccination

The recombinant zoster vaccine (Shingrix) is recommended for all adults aged ≥50 years regardless of prior herpes zoster episodes. 3, 8, 9

Vaccine Recommendations

• Recombinant zoster vaccine (RZV/Shingrix) is superior to live attenuated vaccine 8, 9
• Remarkably effective in restoring protective T cell-mediated immunity 8
• More effective than live zoster vaccine (ZVL) for HZ prevention 9
• Nonreplicating and safe in immunocompromised persons 9
• Can be administered after recovery from herpes zoster to prevent future episodes 3
• Should be given before initiating immunosuppressive therapies like JAK inhibitors 3

Live Zoster Vaccine Considerations (for context)

• Should be administered ≥4 weeks before beginning highly immunosuppressive therapy in eligible patients aged 50-59 years 10
• Recommended for patients ≥60 years receiving low-level immunosuppression 10
• Should NOT be administered to highly immunocompromised patients 10

Post-Exposure Prophylaxis

• Varicella zoster immunoglobulin (or IVIG) within 96 hours of exposure for varicella-susceptible patients 3
• If immunoglobulin unavailable or >96 hours passed: 7-day course of oral acyclovir beginning 7-10 days after exposure 3

Infection Control

• Routine hand hygiene 5
• Appropriate isolation precautions and personal protective equipment 5
• Avoid contact with lesions until all have scabbed 4

Key Clinical Pitfalls

• Do not delay treatment waiting for laboratory confirmation in typical presentations 5
• Do not rely on clinical diagnosis alone in immunocompromised patients or atypical presentations 2
• Do not use topical antivirals as primary therapy 3
• Do not withhold vaccination in patients with prior herpes zoster 3, 5
• Monitor for complete healing of lesions, especially in immunocompromised patients 3
• Caution with nephrotoxic agents due to increased risk of renal dysfunction 4