Varicella-Zoster virus (VZV) is a member of the herpesvirus family and causes two distinct diseases: Varicella (chickenpox) occurs during primary infection and herpes zoster (shingles) during reactivation. After initial infection, the virus remains dormant in the ganglia and may reactivate later in life, especially if the immune system is weakened.
Diseases caused by VZV :
1. Chickenpox (Varicella): -
- A highly contagious disease characterized by itchy rash, fever, and malaise.
- Most common in children, but adults may also develop the disease, which tends to be severe.
- Transmitted by respiratory droplets or direct contact with lesions.
2. Herpes Zoster: -
- Caused by reactivation of dormant VZV. -
- It is characterized by a painful localized rash along a single neurocutaneous segment.
- Risk increases with age or immunosuppression.
sypmtoms :
Chickenpox:
- Fever, fatigue, malaise.
- Rash :
- Begins as red spots and progresses to fluid-filled blisters (vesicles) and scabs.
- Lesions often form “papules” with new lesions forming as the old lesions heal.
- Usually begins on the trunk and spreads to the face, arms, and legs.
Shingles: -
- Pain, burning, or tingling (prodrome) in a specific area.
- Rash: -
Red spots that develop into fluid-filled blisters. - Localized to one side of the body along the nerve pathways (dermatome).
Other symptoms: -
- Headache, fever, malaise.
- Persistent nerve pain (postherpetic neuralgia) may follow the rash.
Transmission:
Chickenpox : -
- Highly contagious from 1 to 2 days before the rash appears until all lesions crust over.
- Transmitted by respiratory droplets or direct contact with vesicle fluid.
Shingles: -
- Not as contagious as chickenpox.
- Direct contact with vesicular fluid from shingles can cause chickenpox in persons who have never had chickenpox or have not been vaccinated.
Complications
1. Chickenpox: -
- Bacterial skin infection.
- Pneumonia (especially in adults).
- Encephalitis or cerebellar ataxia.
- If infected during pregnancy, congenital varicella syndrome.
2. Herpes zoster: -
- Postherpetic neuralgia (PHN):
- nerve pain that persists after the rash has disappeared.
- Sight loss (if ocular nerves are involved).
- Secondary bacterial infections.
- Neurologic complications such as meningitis or myelitis.
Diagnosis
- Clinical manifestations:
typical rash pattern and distribution.
Laboratory tests: -
- PCR: detects VZV DNA (highly sensitive).
- Direct Fluorescent Antibody (DFA): Identifies virus in lesion samples.
- Serology: Detect VZV antibodies to confirm the presence or absence of exposure.
Treatment
1. Chickenpox -
- supportive care
- Antihistamines for itching.
- Acetaminophen for fever (avoid aspirin to prevent Reye's syndrome).
- Antiviral therapy (e.g., aciclovir) in severe cases, adults, and immunocompromised individuals;
2. Herpes zoster: -
- Antivirals (e.g., aciclovir, valacyclovir, or famciclovir) to reduce severity and duration of illness.
- Pain management:
- Over-the-counter or prescription analgesics for severe pain.
- Topical lidocaine or capsaicin cream for localized pain.
- Corticosteroids (in some cases) to reduce inflammation.
vaccinations:
1. Chickenpox Vaccine(Varicella vaccine):
- A live attenuated vaccine given twice in childhood.
- Highly effective in preventing or reducing the severity of chickenpox
.2. Herpes zoster vaccine
- Shingrix (genetically modified vaccine): - Recommended for adults over 50 years of age or those with compromised immunity.
- Significantly reduces the risk of herpes zoster and postherpetic neuralgia.
Prevention:
- Vaccination is the most effective way to prevent VZV-related diseases.
- Avoid contact with infected persons, especially if immunocompromised or unvaccinated. -
- Proper hygiene and covering lesions can help reduce the spread of the virus.
Prognosis:
- Chickenpox: generally mild in healthy children, but may cause complications in adults and immunocompromised patients.
- Herpes zoster: pain and rash usually resolve in 2-4 weeks, but postherpetic neuralgia may persist, especially in the elderly.
With timely treatment and vaccination, VZV-related outcomes are markedly improved and complications are reduced.
