Varicella zoster is a virus that enters the body via droplet inhalation and via direct contact of the fluids expelled from ruptured vesicles. This virus has an incubation period of around 7 days. Once this virus enters the body, the individual becomes infective for about two days before the onset of the characteristic rash and remains infective until all the vesicles have ruptured and crusted over. The vesicles last for about 7 days and, once crusted over, the lesions are not infective. The rash starts on the trunk and spreads outwards to the limbs. First vesicles containing a clear fluid appear. They turn into pustules a few days later.
Chickenpox is common in children. When exposed the body starts producing IgG, IgM and IgA antibodies. IgG is the smallest antibody, and it lasts a lifetime. The immune response limits the primary infection. However, after infection the virus spreads to the nerves and remains dormant in dorsal root ganglia. Reactivation of these latent viruses causes the secondary infection. It manifests as shingles. During pregnancy, the varicella infection is very dangerous. It can cross the placenta and infect the fetus. The effects are much greater in early pregnancy. The outcome is known as congenital varicella syndrome. In late pregnancy, the mother is the one who suffers more. If the mother has had varicella infection earlier in life, she is immune and does not need to be worried about the baby because IgG antibodies cross the placenta and protects the baby. Even though the causative organism is the same the clinical manifestation is very different because of the immune mediated mechanisms. The primary varicella infection results in chickenpox while the reactivation causes shingles. This article outlines the major differences between the two conditions, Chickenpox and Shingles.
Chickenpox | clinical features, symptoms and signs, diagnosis, prognosis, treatment and prevention
Chickenpox is characterized by the appearance of vesicles containing a clear fluid. The vesicles appear first on trunk, most commonly on the back. Then they spread outwards to the limbs. When the vesicles reach the distal limbs, the initial vesicles have ruptured and crusted over. These blisters itch intensely. Vesicles are accompanied by prodromal symptoms like fever, lethargy, muscle pains, loss of appetite and feeling of ill health. Nasal discharge is a common symptom and varicella can be complicated with varicella pneumonia, hepatitis, encephalitis and necrotizing fasciitis. Varicella is not fatal. In adults, the disease is less common but is associated with more complications.
Diagnosis is clinical, and the doctors, by examining the characteristic of vesicles, make the diagnosis. Very rarely Tzanck smear, viral culture may be done if serious doubts are there. Congenital varicella syndrome can be diagnosed with ultrasound scanning before birth. Amniotic fluid PCR may also be needed for confirmation.
Antiviral drugs are rarely needed in varicella. In pregnancy antiviral drugs may be administered. Calamine lotion may help with itching. NSAIDs should not be given to children with fever due to the risk of developing Reye’s syndrome. Acetaminophen (paracetamol) is a good antipyretic. Varicella vaccine given in childhood is a good method of prevention. One dose is not enough for life long immunity, and a second booster dose is therefore needed.
Shingles | clinical features, symptoms and signs, diagnosis, prognosis, treatment and prevention
Shingles is a reactivation of latent varicella virus. Adults who had chickenpox during childhood are at risk of getting shingles. Varicella virus remains dormant in sensory nerve ganglia, and the reactivation causes blisters along the sensory distribution of the same ganglion. The blisters are, therefore, are localized to a single dermatome. These blisters follow the same natural history as those in varicella. There may be a post-herpetic nerve pain which may be severe enough to disturb sleep.
Diagnosis is clinical. Antiviral drugs are generally prescribed. Calamine lotion and acetaminophen may help with the symptoms. Shingles vaccine is advised for adults above 50 years of age who had chickenpox in childhood.
What is the difference between Shingles and Chickenpox?
• Chickenpox is the primary infection while shingles is the reactivation.
• Chicken pox is common in childhood while shingles is common in adulthood.
• Chickenpox rash appears all over the body while shingles rash is localized to a dermatome.
• Chickenpox is rarely complicated while shingles may lead to complications more often.
• Antiviral drugs are advised generally in shingles and not in chickenpox.