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Difficulty: HardPediatric Infectious Diseases

A 6-year-old girl is brought to the pediatric oncology clinic by her father. The patient has acute lymphoblastic leukemia and is currently in the maintenance phase of chemotherapy, which includes daily oral mercaptopurine and weekly oral methotrexate. The father is concerned because the patient's 8-year-old brother was diagnosed with chickenpox yesterday after developing a widespread, pruritic, vesicular rash. The brother's symptoms began 48 hours ago. The patient has no history of clinical chickenpox. Review of her medical record indicates she received her first dose of the varicella vaccine at 12 months of age but missed the second dose. She is currently afebrile and asymptomatic, with an unremarkable physical examination. Which of the following is the most appropriate next step in management?

  1. Administration of varicella-zoster immune globulinAnswer
  2. B
    Administration of the live-attenuated varicella vaccine
  3. C
    Immediate initiation of prophylactic oral acyclovir
  4. D
    Empiric administration of intravenous ceftriaxone
  5. E
    Reassurance and instructions to return for intravenous acyclovir if a rash develops

Answer

The most appropriate next step in management is the administration of varicella-zoster immune globulin (VZIG).
The correct answer is the administration of varicella-zoster immune globulin (VZIG). This patient has a significant household exposure to varicella. Because she is actively receiving immunosuppressive chemotherapy (mercaptopurine and methotrexate) for acute lymphoblastic leukemia, she is considered severely immunocompromised. In this population, exposure to the varicella-zoster virus carries a high risk of life-threatening disseminated disease, including pneumonitis, hepatitis, and encephalitis. The standard of care for post-exposure prophylaxis in immunocompromised individuals, pregnant women, and neonates is passive immunization with VZIG as soon as possible, ideally within 10 days of the exposure.

Step-by-Step Solution

1
Assess the patient's immune status and susceptibility.
The patient is severely immunocompromised due to active maintenance chemotherapy for acute lymphoblastic leukemia.
Immune status dictates the algorithm for post-exposure prophylaxis. Active chemotherapy compromises T-cell function.
2
Determine the significance of the exposure.
Household contact with a sibling who has active chickenpox is a highly significant, high-risk exposure.
Varicella is highly contagious, and household contacts have attack rates exceeding 80%.
3
Select the appropriate prophylactic intervention.
Varicella-zoster immune globulin (VZIG) is selected.
For immunocompromised pediatric patients, VZIG is indicated within 10 days of exposure to prevent or attenuate severe disseminated infection. Live vaccines are contraindicated.

Key Concept

Post-exposure prophylaxis for varicella-zoster virus in severely immunocompromised children requires varicella-zoster immune globulin (VZIG) rather than the live-attenuated vaccine.
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Pediatric Infectious Diseases

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