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Emergency and Acute Medicine: Varicella (Chickenpox)
Varicella is a highly contagious viral illness caused by the varicella-zoster virus (VZV), a DNA virus that establishes lifelong latency in sensory ganglia. It is commonly known as chickenpox and typically affects children, although adults experience more severe disease and have a significantly higher mortality risk. The incidence has decreased substantially due to vaccination.
Transmission occurs via respiratory droplets or direct contact with skin lesions. After primary infection, the virus remains dormant and may reactivate later in life as Herpes zoster. Humans are the only known reservoir. The incubation period ranges from 10 to 21 days, and patients are contagious from about 48 hours before rash onset until all lesions have crusted over.
Clinically, varicella usually begins with a prodrome of low-grade fever, malaise, headache, and anorexia, followed by the characteristic rash. The rash typically starts on the face and spreads to the trunk and extremities. Lesions evolve through stages—papules, vesicles, and crusts—often described as “dew drops on a rose petal.” A key diagnostic feature is the presence of lesions in different stages simultaneously. Mucosal involvement may occur. Pruritus is common, and secondary bacterial infection can complicate the disease.
In adolescents and adults, the disease tends to be more severe, with a higher risk of complications such as pneumonia. Immunocompromised patients (e.g., those with HIV, malignancy, or on immunosuppressive therapy) are at high risk for disseminated disease, hemorrhagic lesions, and prolonged illness. Pregnant patients are also at increased risk of severe complications, including varicella pneumonia, which is a life-threatening emergency. Infection during pregnancy may result in congenital varicella syndrome, characterized by limb hypoplasia, neurologic abnormalities, and ocular defects.
Extracutaneous complications include varicella pneumonitis (more common in adults and smokers), cerebellar ataxia (especially in children), cerebritis, and Reye syndrome, particularly in children given aspirin. Varicella pneumonia typically presents a few days after rash onset with cough, dyspnea, and hypoxia, and may require imaging showing diffuse nodular infiltrates.
Diagnosis is usually clinical based on history and the classic rash. Laboratory confirmation (PCR, viral culture, or direct fluorescent antibody testing) is reserved for atypical or severe cases. Imaging such as chest X-ray is indicated if complications like pneumonia are suspected.
Management in uncomplicated cases is supportive, including antipyretics (acetaminophen) and antipruritic measures. Aspirin should be avoided in children due to the risk of Reye syndrome. Good hygiene and nail care help prevent secondary bacterial infection. Antiviral therapy with acyclovir is recommended for high-risk patients, including adults, adolescents, immunocompromised individuals, and those with chronic medical conditions, ideally within 24 hours of rash onset.
Severe or complicated cases require intravenous antivirals such as acyclovir. Immunocompromised patients often need hospital admission and isolation. Varicella-zoster immune globulin (VZIG) is used for post-exposure prophylaxis in high-risk individuals, including pregnant women without immunity and immunocompromised patients.
Vaccination is highly effective and recommended for all susceptible individuals. Two doses are given in childhood, and unvaccinated adolescents and adults should also receive vaccination unless contraindicated.
Key clinical pearls include recognizing that patients are contagious before rash onset, identifying high-risk groups who require antiviral therapy, and treating varicella pneumonia aggressively, especially in pregnancy.
Emergency and Acute Medicine: Varicella (Chickenpox)
Varicella is a highly contagious viral illness caused by the varicella-zoster virus (VZV), a DNA virus that establishes lifelong latency in sensory ganglia. It is commonly known as chickenpox and typically affects children, although adults experience more severe disease and have a significantly higher mortality risk. The incidence has decreased substantially due to vaccination.
Transmission occurs via respiratory droplets or direct contact with skin lesions. After primary infection, the virus remains dormant and may reactivate later in life as Herpes zoster. Humans are the only known reservoir. The incubation period ranges from 10 to 21 days, and patients are contagious from about 48 hours before rash onset until all lesions have crusted over.
Clinically, varicella usually begins with a prodrome of low-grade fever, malaise, headache, and anorexia, followed by the characteristic rash. The rash typically starts on the face and spreads to the trunk and extremities. Lesions evolve through stages—papules, vesicles, and crusts—often described as “dew drops on a rose petal.” A key diagnostic feature is the presence of lesions in different stages simultaneously. Mucosal involvement may occur. Pruritus is common, and secondary bacterial infection can complicate the disease.
In adolescents and adults, the disease tends to be more severe, with a higher risk of complications such as pneumonia. Immunocompromised patients (e.g., those with HIV, malignancy, or on immunosuppressive therapy) are at high risk for disseminated disease, hemorrhagic lesions, and prolonged illness. Pregnant patients are also at increased risk of severe complications, including varicella pneumonia, which is a life-threatening emergency. Infection during pregnancy may result in congenital varicella syndrome, characterized by limb hypoplasia, neurologic abnormalities, and ocular defects.
Extracutaneous complications include varicella pneumonitis (more common in adults and smokers), cerebellar ataxia (especially in children), cerebritis, and Reye syndrome, particularly in children given aspirin. Varicella pneumonia typically presents a few days after rash onset with cough, dyspnea, and hypoxia, and may require imaging showing diffuse nodular infiltrates.
Diagnosis is usually clinical based on history and the classic rash. Laboratory confirmation (PCR, viral culture, or direct fluorescent antibody testing) is reserved for atypical or severe cases. Imaging such as chest X-ray is indicated if complications like pneumonia are suspected.
Management in uncomplicated cases is supportive, including antipyretics (acetaminophen) and antipruritic measures. Aspirin should be avoided in children due to the risk of Reye syndrome. Good hygiene and nail care help prevent secondary bacterial infection. Antiviral therapy with acyclovir is recommended for high-risk patients, including adults, adolescents, immunocompromised individuals, and those with chronic medical conditions, ideally within 24 hours of rash onset.
Severe or complicated cases require intravenous antivirals such as acyclovir. Immunocompromised patients often need hospital admission and isolation. Varicella-zoster immune globulin (VZIG) is used for post-exposure prophylaxis in high-risk individuals, including pregnant women without immunity and immunocompromised patients.
Vaccination is highly effective and recommended for all susceptible individuals. Two doses are given in childhood, and unvaccinated adolescents and adults should also receive vaccination unless contraindicated.
Key clinical pearls include recognizing that patients are contagious before rash onset, identifying high-risk groups who require antiviral therapy, and treating varicella pneumonia aggressively, especially in pregnancy.
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