Overview
Chickenpox is a viral infection caused by the varicella-zoster virus (VZV), leading to widespread symptoms throughout the body. It is characterized by itchy skin rashes and fluid-filled blisters.
Affected Systems
Medical Departments: Pediatrics, Infectious Disease
Affected Body Parts: Entire body
Definition
Chickenpox is an acute viral illness triggered by the varicella-zoster virus (VZV). It begins with a mild fever and progresses to itchy rashes and blisters that appear all over the body. The incubation period ranges from 2 to 3 weeks, with symptoms typically appearing around 13-17 days post-infection. Transmission occurs through direct contact with fluid from the blisters or through airborne droplets. It can also spread via saliva. The blisters are most contagious in the early stages before scabbing over. Once scabs form, the risk of transmission significantly decreases.
Causes
Chickenpox is caused by the varicella-zoster virus (VZV), a member of the
Herpesviridae family, specifically the
Alphaherpesviridae subfamily.
Symptoms
The incubation period lasts 2 to 3 weeks, with most symptoms appearing 13-17 days after exposure. It typically begins with a mild fever, followed by an itchy skin rash. The rash progresses through different stages:
- First, small red spots (macules).
- Next, raised bumps (papules).
- Then, fluid-filled blisters (vesicles) which dry up and form scabs within 7-10 days.
During this process, blisters can be found in various stages at the same time. The blisters tend to appear more in covered areas like the scalp, underarms, and mucous membranes, including the mouth and eyes. Blisters may also form in areas exposed to friction, such as around the waistline. Adults may experience more severe symptoms, including a high fever and systemic symptoms.
Atypical Cases
While most cases show the classic progression, some may present with milder symptoms or even asymptomatic infections. However, asymptomatic cases are rare.
Diagnosis
Diagnosis is usually based on clinical observation of the characteristic rash and blisters. Laboratory tests may include the detection of multinucleated giant cells with viral inclusion bodies in blister samples. Other methods include observing the virus under an electron microscope, virus isolation through cell cultures, or detecting viral antigens directly. Blood tests can also confirm the infection through serological analysis.
Treatment
Chickenpox generally resolves on its own, so most cases do not require specific treatment. However, in immunocompromised individuals, antiviral medications like
acyclovir or
vidarabine may help alleviate symptoms. In otherwise healthy individuals, antiviral treatment offers minimal benefit, shortening symptoms by only half a day to two days. As such, routine antiviral use is not recommended unless symptoms are severe or involve the trigeminal nerve.
Prognosis and Complications
The overall mortality rate for chickenpox is approximately 2 per 100,000 cases, but it increases to 30 per 100,000 among adults, making adult cases more dangerous. Severe complications in adults often include viral pneumonia, while children are more at risk for secondary bacterial infections and encephalitis. Patients with leukemia face a high risk, with a mortality rate between 5-10%. If a mother contracts chickenpox within 5 days before or 2 days after childbirth, the newborn faces a high risk of severe chickenpox within 5-10 days after birth, with a mortality rate of around 30%. Infection during early pregnancy carries a small risk (around 2%) of causing congenital defects.
Prevention
High-risk groups, such as immunocompromised individuals and newborns, should avoid contact with infected persons. A live attenuated
chickenpox vaccine is available and is recommended for children aged 1-12 who have not yet been exposed. A single 0.5 mL dose provides protection for 3-6 years in 70-90% of cases. For adults, two doses given 4-8 weeks apart offer about 70% effectiveness. Leukemia patients are also recommended to receive two doses. While vaccinated individuals can still contract the virus, their symptoms tend to be much milder. Vaccination can cause mild, chickenpox-like rashes in about 7% of recipients. Though less common than in natural infection, the vaccine can later lead to shingles (herpes zoster).
Diet and Lifestyle
No specific dietary adjustments are required for those with chickenpox. It is recommended to isolate patients for about 5 days after the initial onset of symptoms or until the blisters have dried. This helps prevent spreading the virus in schools, hospitals, and other facilities. In hospitals, particularly those treating immunocompromised patients, strict isolation of chickenpox patients is necessary to prevent severe outbreaks.
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