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Managing a Langerhans Cell Histiocytosis (LCH) patient with chickenpox (Varicella Zoster Virus - VZV) contact is a serious matter, as LCH patients are immunocompromised, making them highly vulnerable to severe VZV infection. Chickenpox in immunocompromised individuals can lead to serious complications, including widespread disease, pneumonia, encephalitis, and even death.

The management strategy focuses on urgent assessment, post-exposure prophylaxis (PEP), and prompt treatment if disease develops. This is a critical situation that requires immediate communication with the patient's oncology/hematology team.

Here's a breakdown of the typical management approach, based on current UK NHS guidelines (as of early 2025):

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Management (Mx) Plan for LCH Patient with Chickenpox Contact

1. Urgent Risk Assessment and Communication (Immediate Action)

• Contact the LCH Team Immediately: This is the most crucial first step. The patient's primary LCH consultant or specialist nurse/team should be informed without delay, regardless of the time of day. They will guide the specific protocol based on the patient's current treatment, disease activity, and immune status.
• Assess Immunocompromised Status: The LCH team will determine the patient's degree of immunosuppression, which influences the risk and the type of prophylaxis needed. Factors include:
  • Current LCH treatment (e.g., chemotherapy, steroids, targeted therapies).
  • Time since last treatment.
  • Blood counts (especially lymphocyte count).
  • Severity and extent of LCH.
• Assess "Significant Exposure": Determine if the contact was truly significant. This is generally defined as:
  • Household contact with a chickenpox case.
  • Contact in the same small room (e.g., classroom, hospital bay) for $\ge 15$ minutes.
  • Face-to-face contact (e.g., conversation).
  • Contact during the infectious period of the source case (from 24-48 hours before rash onset until all lesions have crusted over).

2. Assess VZV Immunity (If Status Unknown)

• VZV IgG Serology: If the patient's VZV antibody (IgG) status is unknown, an urgent blood test should be performed. This determines if they have prior immunity from a past infection or vaccination.
  • Crucial Note: Even if VZV IgG positive, some LCH patients, especially those on active chemotherapy, may not have sufficient protective immunity due to their immunosuppression. Therefore, prophylaxis is often still recommended regardless of serology in actively treated LCH patients.

3. Post-Exposure Prophylaxis (PEP)

• First-Line PEP: Oral Aciclovir (or Valaciclovir):
  • This is now the preferred first-line PEP for most susceptible immunocompromised individuals in the UK, including LCH patients.
  • Timing: Aciclovir prophylaxis should ideally be started from Day 7 to Day 14 after the first day of exposure. Starting earlier than Day 7 may interfere with the immune response. If the patient presents after Day 7, a 7-day course can still be given up to Day 14 after exposure.
  • Dose: Dosing is weight-based for children and typically higher than standard prophylactic doses for immunocompetent individuals (e.g., 10 mg/kg four times daily for children 2-17 years, up to a maximum of 800mg per dose). Neonatal dosing (under 2 years) is typically 10mg/kg four times daily.
  • Valaciclovir: May be considered for older children (generally 2+ years) if adherence is an issue, due to its fewer daily doses and better bioavailability (dosing is typically 20 mg/kg up to 1000mg three times daily).
• Varicella Zoster Immunoglobulin (VZIG) / Hyperimmune Product:
  • Historically, VZIG was first-line, but due to supply issues and evidence of aciclovir efficacy, it's now primarily reserved for specific situations where oral antivirals are contraindicated or cannot be absorbed (e.g., severe renal impairment, severe malabsorption).
  • If indicated, it should be given by slow intramuscular injection, ideally within 7-10 days of exposure. In the UK, products like Varitect CP or normal intravenous immunoglobulin (IVIG) may be used if VZIG is unavailable.
• Vaccination (Not for immediate PEP): The VZV vaccine is a live vaccine and is contraindicated for most LCH patients while on immunosuppressive therapy or for a period after stopping it. It is not used for immediate post-exposure prophylaxis.

4. Monitoring for Breakthrough Disease

• Even with PEP, breakthrough chickenpox can occur. The LCH patient (and parents/caregivers) must be vigilant for any signs of rash, fever, or feeling unwell during the incubation period and beyond the prophylaxis window.
• If Rash Develops: If a VZV rash appears, it requires immediate and aggressive treatment with intravenous (IV) aciclovir. This usually necessitates hospital admission.
  • Higher Dose IV Aciclovir: The dose for active infection in immunocompromised patients is significantly higher (e.g., 500mg/m2 or 10mg/kg every 8 hours, usually for 5-7 days or until no new lesions for 48 hours).
  • Monitoring for Complications: Close monitoring for complications such as pneumonia, encephalitis, hepatitis, or secondary bacterial infections is essential.

5. Infection Control Measures

• Isolation: If the LCH patient develops chickenpox, they should be isolated (e.g., in a single room with negative pressure if hospitalized) to prevent spread to other vulnerable individuals.
• Hand Hygiene: Continued strict hand hygiene.

Key Takeaways:

• IMMEDIATE action and communication with the LCH team are paramount.
• LCH patients are highly vulnerable to severe chickenpox.
• Post-exposure prophylaxis with oral aciclovir (or valaciclovir) is the standard in the UK, typically started Day 7-14 post-exposure.
• If chickenpox develops despite PEP, prompt IV antiviral treatment is critical.

This is a general overview; actual management will always be determined by the patient's specific LCH diagnosis, treatment phase, individual risk factors, and the most current local and national clinical guidelines (e.g., those from the British Society for Haematology or specific NHS Trust protocols).