Chickenpox

Disease Description (Causes and Symptoms)

• Cause: Varicella (chickenpox) is caused by infection with the varicella-zoster virus (VZV).
• Pathophysiology: After an initial respiratory infection, the virus spreads throughout the body via the bloodstream and causes a characteristic vesicular rash on the skin. The virus can remain latent in the peripheral nerve ganglia and later reactivate as shingles.
• Main symptoms: After 2–3 weeks (the incubation period), low-grade fever, headache, muscle aches, loss of appetite, and sweating may occur (in adults, 1–2 days after the onset of fever), followed by a generalized rash that progresses from small papules → vesicles → pustules/scabs. The coexistence of lesions at multiple stages at the same time is characteristic. Itching and secondary bacterial infection may occur. It is highly contagious, and nearly all susceptible contacts become infected. It is common in children (mainly ages 5–9), with a higher seasonal incidence from late fall to early spring.

Treatment

• General principles: Most cases resolve spontaneously and have a favorable course with symptomatic treatment. The basics are symptom management (pain relief and fever reduction, itch relief) and prevention and treatment of secondary bacterial infection.
• Medication treatment
  • Antiviral medication: For high-risk groups (immunocompromised individuals, adults, people with chronic lung or skin disease, pregnant women exposed to the virus, etc.) or when severe disease or complications are a concern, early oral acyclovir is recommended (within 24–72 hours of rash onset).
    • Example dosage (must be confirmed with a clinician): 20 mg/kg per dose for children (maximum 800 mg) 4 times/day; 800 mg for adults 4–5 times/day; the usual treatment duration is 5–7 days. (The exact dose and duration are adjusted according to the patient’s condition.)
  • Antihistamines (to relieve itching), topical calamine lotion, and other symptomatic treatments.
  • Fever reduction: Acetaminophen (Tylenol) is recommended. Do not use aspirin (risk of Reye syndrome).
• Prevention and special treatment
  • Vaccine: Vaccination (generally a 2-dose schedule) greatly reduces the incidence and severity of chickenpox. Vaccination is also recommended for adults who are unvaccinated after their immunity status has been assessed.
  • Post-exposure management: For high-risk individuals exposed to the virus (pregnant women, immunocompromised individuals, newborns), consider varicella-zoster immune globulin (VZIG) or medical observation. Vaccination within 3–5 days after exposure may prevent or lessen the disease.
• Indications for hospitalization: Pneumonia, encephalitis, severe systemic infection, immunocompromised status, newborns or infants, or suspected severe complications.
• Isolation: Isolation (infection prevention) is necessary because the disease remains contagious until all lesions have formed scabs.

Checklist Before an Outpatient Visit (Including Example Questions)

Items to prepare and points to check

• The date the rash began and the time the first symptoms appeared (record the course of the rash and fever)
• Exposure history (when and with whom contact occurred) and whether there are other patients in the household
• A list of currently taken medications (including anticoagulants, steroids, and immunosuppressants)
• Underlying conditions (asthma, chronic lung disease, skin disease, diabetes, immunosuppressed status, etc.)
• Recent vaccination history (whether the chickenpox vaccine was received and when)
• Possibility of pregnancy or whether pregnant (for women)
• For children: vaccination records and date of birth
• Signs of worsening symptoms (difficulty breathing, persistent high fever, seizures, changes in consciousness, etc.)

Materials that can be shown to the doctor during the outpatient visit

• Photos of the rash (early appearance and progression)
• Temperature records and photos or labels of medications being taken

General Example Questions to Ask the Doctor

• How dangerous is this condition? What is the prognosis?
• Do I need antiviral medication (acyclovir)? When should it be started to be effective?
• What medications can I take? (Such as fever-reducing or anti-itch medications.) What are the side effects?
• When can isolation end (when can I resume daily activities and return to school or work)?
• What should I be careful about at home to reduce the risk of complications?
• If family members (especially pregnant women, newborns, or immunocompromised individuals) have been exposed, what should we do?

Examples of Condition-Specific Questions

• (Pregnant woman) I have been exposed to chickenpox or suspect that I have symptoms. What risks are there to the fetus (or the course of the pregnancy), and are additional tests or treatment needed?
• (Immunocompromised patient or caregiver) I am immunosuppressed. In what situations are antiviral treatment, hospitalization, or VZIG administration needed? Should I go to the hospital immediately?

Additional Information

• Complications: Secondary bacterial infection, pneumonia, encephalitis, varicella viral pneumonia, sepsis, arthritis, osteomyelitis, localized gangrene, Reye syndrome, etc.
• Prevention: Vaccination (2-dose schedule) and early action after exposure (vaccination or VZIG) are important.
• Emergency signs: If difficulty breathing, changes in consciousness, persistent high fever, or seizures occur, immediate evaluation in an emergency room is recommended.