Chickenpox: what kind of disease it is, the virus, and what it resembles

Chickenpox (varicella) is an acute viral disease that spreads very easily and most often occurs in children. In most people it resolves on its own within 1–2 weeks, but in adults, newborns, and people with weakened immunity it can be severe. Below is the general picture: the causative agent, its relationship to herpes, and how it differs from true smallpox.

What chickenpox is and why it is called chickenpox

Chickenpox (Latin: varicella) is a highly contagious viral infection transmitted by airborne droplets. The typical picture is fever and a papulovesicular rash. "Chickenpox" is the everyday shortened form of the same name; "Turkish chickenpox" also refers to ordinary chickenpox—there is no separate disease behind this expression.

Contagiousness approaches 100%: anyone who has not previously encountered the virus becomes infected. People of all ages are affected, predominantly children: about half of children contract the infection at ages 5–9, less often at 1–4 and 10–14 years, and about 10% of cases are 14 years and older.

Varicella-zoster virus: its connection to herpes and shingles

The causative agent is the varicella-zoster virus (Varicella Zoster) from the Herpesviridae family, also known as human herpesvirus type 3. The same virus causes two diseases: chickenpox as the primary infection and herpes zoster (shingles) as a result of reactivation of the virus that has persisted in nervous tissue for years.

Immunity protects against reinfection but does not eliminate the virus: it remains for life in the spinal ganglia and nuclei of the cranial nerves. In 10–20% of those who have had the disease, the virus reactivates and causes shingles. The incidence is 131–215 cases per 100,000 population: 46 in people under 15 years and 1,424 in people over 75; in vaccinated individuals—2.6 per 100,000.

Chickenpox and true smallpox: what the difference is

Historically, these diseases were confused: in the 16th century chickenpox was described as a variant of smallpox, the term "varicella" itself appeared in 1772, and the disease was recognized as a separate entity in 1911, when the causative agent was found in the contents of vesicles. The virus was isolated in 1958.

Today it is an independent infection with its own causative agent—the varicella-zoster virus—and not a mild form of smallpox.

How chickenpox manifests

The main symptom is an itchy spotted rash that can appear on any part of the body, including in the mouth and around the genitals, where it can be painful. On brown and black skin, the lesions are harder to notice. Before or after the rash, there may be high fever, aches and pains, general malaise, and loss of appetite.

The rash goes through three stages: small spots, then fluid-filled blisters that itch intensely and may rupture, then crusts. New lesions appear while others are already turning into blisters or becoming crusted. The incubation period lasts 10–21 days, more often 14–16. The patient is contagious from the end of the incubation period, 48 hours before the rash appears, and until all lesions have crusted over—usually 7–10 days. The illness most often lasts 5–10 days, and recovery takes 1–2 weeks.

Diseases similar to chickenpox and what it is confused with

The same virus causes herpes zoster (shingles): this is the result of reactivation of the virus that has persisted in nervous tissue for years, and it manifests as localized skin eruptions. Chickenpox and rubella are different diseases; chickenpox is caused by the varicella-zoster virus.

Laboratory diagnosis includes serological antibody tests and tests for chickenpox and shingles.

When to see a doctor

In most children, chickenpox is mild and resolves on its own without a doctor's visit. More severe disease occurs in:

• adults—after age 18 the course is more often severe, with mortality 25–175 times higher than in children;
• newborns and infants;
• adolescents;
• pregnant women;
• people with weakened immunity.

Complications vary—from bacterial skin superinfection and pneumonia to otitis media and hepatitis. Neurological complications account for 1–7.5% of cases, of which 70.5% are encephalitis and 10.6% are meningitis. A separate risk is neonatal chickenpox: if the mother develops the disease 5 days before delivery or in the first 2 days after, it is fatal in 30% of cases.

Chickenpox itself is not a reason to call an ambulance; 103/112—if the condition is life-threatening, for example if a severe complication is suspected (encephalitis, pneumonia). Separately—a newborn whose mother developed the disease 5 days before delivery or in the first 2 days after.

This is reference material: it does not replace consultation with a doctor who sees the specific patient and makes the decision.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer