Chickenpox, or varicella, is an acute, highly contagious viral infection caused by the varicella-zoster virus (VZV), a member of the herpesvirus family. This condition is most commonly observed in children and is often considered a mild, self-limiting illness in healthy individuals. However, chickenpox can lead to serious complications in certain high-risk groups, such as infants, immunocompromised patients, pregnant women, and adults without prior immunity.
The disease is characterized by systemic symptoms such as fatigue, malaise, low-grade fever, and anorexia, which are followed by a classic exanthem—an intensely itchy rash composed of macules, papules, vesicles, pustules, and crusts, often present simultaneously in different stages of evolution. The rash begins on the trunk and rapidly spreads to the face, scalp, and extremities. In more severe cases, lesions may also be present in mucous membranes, including the mouth and genitals.
Chickenpox is highly infectious, with transmission occurring via airborne respiratory droplets or direct contact with fluid from ruptured vesicles. Coughing, sneezing, or touching contaminated surfaces facilitates the spread of the virus, especially in enclosed environments such as households, schools, and daycare centers. The contagious period begins approximately 1–2 days before the appearance of the rash and continues until all lesions have crusted over, typically 7–10 days after onset.
Chickenpox most commonly affects children between the ages of 5 and 9. However, with the increasing use of early childhood education centers, more cases are now seen in preschool-aged children. The infection rate is extremely high—up to 90% of susceptible individuals develop the disease upon exposure to the virus.
Seasonal patterns show a higher incidence of chickenpox in the winter and spring months, particularly in temperate regions. Once infected, individuals generally develop lifelong immunity to chickenpox, although the virus remains dormant in the body. In some cases, it may reactivate later in life as herpes zoster (shingles), a condition that causes painful nerve inflammation and skin rashes, typically in individuals over 60 years of age or in immunocompromised patients.
Following inhalation or mucosal contact, the varicella-zoster virus infects the epithelial cells of the upper respiratory tract. From there, it disseminates through regional lymph nodes and enters the bloodstream (primary viremia). The virus then localizes in the reticuloendothelial system, where it replicates further. A secondary viremia results in widespread dissemination to the skin and mucous membranes, where the characteristic rash develops. The virus also establishes latency in the dorsal root ganglia of sensory nerves, from which it may later reactivate as shingles.
This mechanism of lifelong latency is a hallmark of herpesviruses, and it underscores the importance of early childhood exposure, vaccination, and long-term monitoring of individuals with a weakened immune response.
Clinical symptoms of chickenpox typically appear 10 to 21 days after exposure to the virus. The disease usually begins with a prodromal phase characterized by fatigue, low-grade fever, headache, malaise, and loss of appetite. In children, this phase may be very mild or absent; in adults, systemic symptoms tend to be more pronounced.
Within 24 hours of onset, a characteristic skin rash appears. The rash usually starts on the chest and back, then spreads rapidly to the face, scalp, arms, legs, and sometimes to mucous membranes (oral cavity, conjunctiva, and genitals).
The rash progresses through several distinct stages:
Itching is typically severe and may lead to scratching, which increases the risk of secondary bacterial infection and scarring. Chickenpox lesions can vary in number: some individuals have only a few spots, while others may develop hundreds.
In most cases, the diagnosis of chickenpox is clinical and based on the presence of the classic skin lesions in multiple stages of development, along with systemic symptoms such as fever and malaise. However, in atypical presentations or in immunocompromised patients, additional diagnostic tests may be required.
Diagnostic tools include:
In all suspected cases, especially in children under 1 year of age, pregnant women, or immunocompromised individuals, it is critical to consult a physician or infectious disease specialist promptly for appropriate monitoring and care planning.
In healthy children with no underlying conditions, chickenpox is usually self-limiting and requires only symptomatic treatment. The goal is to alleviate discomfort and prevent complications.
In high-risk individuals, such as pregnant women, immunocompromised patients, and neonates, antiviral medications like acyclovir, valacyclovir, or famciclovir may be prescribed. For maximum effectiveness, therapy should be initiated within 24–48 hours of symptom onset.
Varicella-zoster immune globulin (VZIG) may be administered as post-exposure prophylaxis in at-risk individuals to reduce disease severity.
While typically mild, chickenpox can occasionally result in serious complications that necessitate hospitalization and aggressive treatment. The most frequent complications include:
High-risk groups—especially pregnant women, newborns, HIV-positive individuals, cancer patients, and those on immunosuppressive therapy—require close monitoring and early antiviral therapy to reduce morbidity and mortality.
Chickenpox is contagious from 1–2 days before the rash appears until all lesions have crusted over. This infectious period presents a major challenge for preventing transmission, especially in schools and daycare settings.
To reduce the spread of the virus:
The most effective strategy for chickenpox prevention is vaccination. The varicella vaccine is a live attenuated virus vaccine administered in one or two doses, depending on age and national immunization schedules. A single dose provides approximately 99% protection against severe forms and 80% protection against all forms of the disease.
Post-exposure vaccination within 3–5 days of contact with an infected individual can still prevent or significantly reduce disease severity. Vaccination is especially important for:
By combining vaccination, public health measures, and timely medical care, the burden of chickenpox and its complications can be substantially reduced, especially in high-risk populations.
