Signs and Symptoms of Varicella-Zoster Virus (VZV) Infection
Varicella-zoster virus infection presents with distinct clinical manifestations depending on whether it's a primary infection (chickenpox) or reactivation (herpes zoster/shingles), characterized primarily by fever and vesicular skin lesions that progress through multiple stages of development.
Primary VZV Infection (Chickenpox)
Incubation and Prodromal Phase
- Incubation period averages 14-16 days (range: 10-21 days) after exposure to the virus 1
- Infected persons are contagious approximately 1-2 days before rash onset until all lesions are crusted 1
- Prodromal symptoms may include fever, malaise, and symptoms resembling upper respiratory tract infection 1
Characteristic Rash
- Cutaneous lesions begin as macules and rapidly progress through stages: papules, vesicles, pustules, and finally scabs 1
- Rash typically starts on the trunk and head, then spreads to extremities (centripetal distribution) 1
- Most children develop 250-500 skin lesions in the classic form of disease 1
- Lesions appear in successive crops, with multiple stages of development present simultaneously 1, 2
- Fever and rash typically last approximately 5 days 1
Other Clinical Features
- Lesions frequently develop in the mouth, conjunctivae, or other mucosal sites 1
- Secondary bacterial skin infections may occur as a complication 3
- In vaccinated individuals (breakthrough varicella), the presentation is often modified with fewer lesions (<50), predominantly maculopapular rather than vesicular, milder fever, and shorter illness duration 1
VZV Reactivation (Herpes Zoster/Shingles)
Prodromal Phase
- Prodromal pain often precedes skin findings by 24-72 hours 4
- Pain may be accompanied by tingling, itching, or burning in the affected dermatome 5, 6
Characteristic Rash
- Unilateral, dermatomal distribution of vesicular lesions 1, 4
- Lesions progress from erythematous macules to papules and then to vesicles, which may coalesce and form bullae before scabbing 4
- Vesicles continue to erupt for 4-6 days with total disease duration of approximately 2 weeks in immunocompetent hosts 4
- In immunocompromised patients, skin lesions may develop over a longer period (7-14 days) and heal more slowly 4
Distinctive Signs
- Pleomorphic or non-excavated pseudodendritic epithelial keratitis of cornea or conjunctiva may be present in ocular involvement 1
- Vesicular dermatomal rash or ulceration of eyelids in ophthalmic zoster 1
Complications
Post-Herpetic Neuralgia
- Chronic pain persisting after the rash heals, more common in older adults 5, 7
- Most frequent and important complication of VZV reactivation 6
Neurological Complications
- VZV reactivation can cause various neurological syndromes including vasculitis, encephalitis, myelopathy, and cranial neuropathies 6
- Zoster sine herpete: VZV reactivation without the characteristic rash 6
Ocular Complications
- Conjunctival scarring, keratitis, corneal scarring, uveitis, and retinitis may occur 1
- Necrosis and scarring from vesicles on the eyelid margins 1
Complications in Immunocompromised Patients
- Higher risk of disseminated disease with involvement of multiple organs including liver and brain 3
- Without adequate treatment, chronic ulcerations with persistent viral replication may develop, complicated by secondary bacterial and fungal superinfections 4
Special Considerations
- Adult cases tend to be more severe than childhood cases 3
- Immunocompromised individuals have higher risk of complications 4, 3
- Pregnant women may experience more severe disease due to altered immune response 3
Understanding these clinical manifestations is crucial for prompt diagnosis and appropriate management of VZV infections to prevent complications and reduce morbidity.