Varicella

Varicella, commonly known as chickenpox, is a highly contagious human disease caused by varicella zoster virus (VZV), which is a DNA virus classified within the herpesvirus family. The infection is characterized by a generalized vesicular rash and represents the primary manifestation of initial VZV infection in individuals without prior immunity. Following clinical recovery, the virus establishes lifelong latency in dorsal root ganglion cells of sensory nerves.

The illness presents with a characteristic pruritic rash that evolves through sequential stages: macules, papules, vesicles, pustules, and finally crusting scabs. The rash typically appears first on the chest, back, and face before spreading to the remainder of the body. Constitutional symptoms including fever, fatigue, and headache accompany the rash and persist for approximately five to seven days. In adolescents and adults, prodromal symptoms such as nausea, myalgia, and headache often precede the rash by one to two days, whereas children usually present with rash as the initial manifestation. Serious complications occur occasionally and include viral pneumonia, encephalitis, and secondary bacterial skin infections. Adults typically experience more severe disease than children.

Varicella occurs worldwide and represents a highly transmissible infection with an incubation period of 10 to 21 days following exposure. The disease is endemic in populations lacking universal immunization, where it primarily affects children. Outbreak patterns reflect the highly contagious nature of the virus and its efficient person-to-person transmission dynamics. Surveillance systems track incidence to monitor vaccine program effectiveness and identify susceptibility gaps in populations.

VZV spreads primarily through airborne respiratory droplets generated by coughing or sneezing of infected individuals. Direct contact with vesicular fluid from skin lesions also facilitates transmission. Infected persons become contagious approximately one to two days before the appearance of the characteristic rash and remain infectious until all lesions have fully crusted over. Individuals with reactivated infection (herpes zoster) can transmit VZV to susceptible contacts through contact with blister fluid.

Adults experience more severe varicella than children, with higher rates of complications including pneumonia. Pregnant women face dual risks: primary infection during the first 28 weeks of gestation can result in fetal varicella syndrome (congenital varicella syndrome), with manifestations ranging from limb hypoplasia to severe neurologic and ocular abnormalities, while infection in the third trimester is associated with more severe maternal symptoms. Immunocompromised individuals are at elevated risk for disseminated disease and complications.

Source-backed prevention detail is not yet available. General vaccination information from the source mentions shingles vaccination programs for adults aged 50 years and older in the United States and routine shingles vaccination for adults aged 70-80 in England beginning in 2013.

Clinical diagnosis of varicella is typically based on the characteristic rash pattern and associated symptoms, particularly in outbreak settings with typical epidemiology. Laboratory confirmation may be obtained through polymerase chain reaction (PCR) detection of VZV DNA in vesicular fluid or scab material. Serologic testing for VZV-specific IgM antibodies can support acute diagnosis, while IgG antibody detection indicates past infection or immunity. Surveillance should account for the distinctive rash morphology, age distribution of cases, and vaccination status to distinguish wild-type infection from breakthrough cases.

1. 1 Wikidata. chickenpox.
2. 2 Wikipedia. Chickenpox - Wikipedia.

ICD-10

B01

ICD-11

KA62.0

Total cases

1.2M

Total deaths

1

Peak month

2026-01

Coverage

4 reporting countries · 2000-01-01 → 2026-05-09