What are the recommended management strategies for chicken pox?

Chickenpox Management

For immunocompetent patients, oral acyclovir should be initiated within 24 hours of rash onset at 800 mg four times daily for 5 days in adults and adolescents ≥12 years, or 20 mg/kg (maximum 800 mg) four times daily for 5 days in children, while immunocompromised patients require intravenous acyclovir 10 mg/kg every 8 hours for 7-10 days. 1, 2, 3

Antiviral Treatment by Patient Population

Immunocompetent Patients

Children (<40-45 kg):

• Oral acyclovir 20 mg/kg per dose (maximum 800 mg) four times daily for 5 days 1, 4, 3
• Treatment must be initiated within 24 hours of rash onset for maximum efficacy, as delayed initiation significantly reduces clinical benefit 1, 3

Adolescents ≥12 years and Children >40 kg:

• Oral acyclovir 800 mg four times daily for 5 days 1, 4, 3
• The FDA label specifies this dosing for children over 40 kg and adults 3

Adults:

• Oral acyclovir 800 mg four times daily for 5-7 days 1, 2, 3
• Adults tend to have more severe disease than children and should be prioritized for treatment 1, 3

Immunocompromised Patients

Critical distinction: These patients require intravenous therapy, not oral 1, 2, 4

• Intravenous acyclovir 10 mg/kg every 8 hours for 7-10 days or until no new lesions appear for 48 hours 1, 2, 4, 3
• Some experts recommend dosing based on body surface area in children >1 year: 500 mg/m²/dose IV every 8 hours 1
• Consider discontinuing immunomodulator therapy in severe cases if clinically feasible 2

High-Risk Groups Requiring Antiviral Treatment

The following groups should receive acyclovir therapy even if immunocompetent 1, 2, 4:

• Adolescents ≥12 years and adults (higher risk of severe disease) 1, 4
• Patients with chronic cutaneous or pulmonary disorders 1, 2, 4
• Patients receiving long-term salicylate therapy (due to Reye's syndrome risk) 1, 2, 4
• Patients on short, intermittent, or aerosolized corticosteroid therapy 1, 2
• Secondary household contacts of infected children 1
• Pregnant women (though routine use is not generally recommended; acyclovir is Pregnancy Category B) 1, 3

Post-Exposure Prophylaxis

First-Line: Varicella Zoster Immune Globulin (VZIG)

Administer VZIG as soon as possible, up to 96 hours after exposure (some sources state up to 10 days) to the following groups 1, 2, 4:

• Susceptible immunocompromised patients 1, 2, 4
• Pregnant women without evidence of immunity 1, 4
• Neonates born to mothers with varicella 5 days before to 2 days after delivery 1, 4
• Premature infants <28 weeks gestation or <1,000 g regardless of maternal immunity 1, 4

Important caveat: VZIG may prolong the incubation period to 28 days, requiring extended monitoring 2

Alternative: Acyclovir Prophylaxis

If VZIG is unavailable:

• Oral acyclovir 10 mg/kg four times daily for 7 days, starting 7-10 days after exposure 1, 2, 4
• Acyclovir is not indicated for prophylactic use in healthy individuals after exposure 1

Post-Exposure Vaccination

• Vaccination within 3-5 days of exposure may modify disease if infection has not yet occurred 2
• Delay varicella vaccination 5 months after VZIG administration 1, 4

Timing of Treatment Initiation: Critical Consideration

The 24-hour window is paramount: Treatment initiated within 24 hours of rash onset provides maximum clinical benefit 1, 3. The FDA label explicitly states "there is no information about the efficacy of therapy initiated more than 24 hours after onset of signs and symptoms" 3. This represents a clear gradient in treatment efficacy, with diminishing returns after this window 1.

Duration of Therapy

• Immunocompetent patients: 5 days is sufficient, as a 7-day course provides no additional benefit 1, 3
• Immunocompromised patients: 7-10 days of IV therapy or until no new lesions appear for 48 hours 1, 2, 4

Infection Control Measures

• Isolate patients until all lesions have crusted over 1, 2, 4
• Healthcare workers without immunity exposed to VZV should be furloughed from days 10-21 after exposure 5, 1, 2, 4
• Healthcare workers with 1 dose of vaccine should receive the second dose within 3-5 days of exposure 5, 2
• Healthcare workers with 2 doses of vaccine should be monitored daily for fever and rash on days 8-21 post-exposure 2

Vaccination Considerations in Treatment Context

• Live varicella vaccination is contraindicated in immunocompromised patients due to risk of disseminated infection 1, 2, 4
• Susceptible household contacts of immunocompromised patients should be vaccinated to prevent transmission 1, 4
• For patients on immunomodulators unable to receive live vaccination, advise seeking post-exposure prophylaxis if exposed to active chickenpox or herpes zoster 1

Dosage Adjustment for Renal Impairment

Critical for preventing nephrotoxicity: Dosage must be adjusted based on creatinine clearance 3

For 800 mg every 4 hours regimen:

• Creatinine clearance >25 mL/min: 800 mg every 4 hours, 5 times daily 3
• Creatinine clearance 10-25 mL/min: 800 mg every 8 hours 3
• Creatinine clearance 0-10 mL/min: 800 mg every 12 hours 3

Hemodialysis patients: Administer an additional dose after each dialysis session 3

Symptomatic Management

Antipyretics:

• Use paracetamol (acetaminophen) for fever control 6, 7
• Avoid NSAIDs (especially ibuprofen) due to potential increased risk of severe bacterial skin infections, including necrotizing fasciitis 6, 7

Pruritus management:

• Antihistamines may be used for symptomatic relief of itching 6
• Maintain adequate hydration 3

Important Clinical Caveats

• Acyclovir does not eradicate latent virus or affect subsequent risk, frequency, or severity of herpes zoster recurrences 1
• Antibody titers after infection in children receiving acyclovir do not differ substantially from untreated patients 1
• Antibody titers are unreliable in patients with nephrotic-range proteinuria or receiving IVIG 4
• Caution should be exercised when administering acyclovir to patients receiving potentially nephrotoxic agents 3
• Adequate hydration should be maintained to prevent renal dysfunction 3

Outbreak Control

• Varicella vaccination is recommended for outbreak control 5
• Persons without adequate evidence of immunity should receive their first or second dose as appropriate 5
• In outbreaks among preschool-aged children, 2-dose vaccination is recommended, with the second dose given if 3 months have elapsed since the first dose 5
• Unvaccinated persons without evidence of immunity should be excluded from institutions until 21 days after the onset of rash in the last case 5