Varicella (chicken pox)

December 8, 2023

 

Unless stated otherwise, the NWT Office of the Chief Public Health Officer (OCPHO) is using the information regarding diagnosis, overview of communicable disease and public health measures found in the Alberta Health Services Public Health Disease Management Guidelines.

Note: Any additional information that is NWT specific will be found on this page and supersedes the direction provided in the Alberta Health Services resource. This includes but is not limited to reporting requirements and specified public health measures set out below.

See Alberta Public Health Disease Management Guidelines: varicella (chicken pox).

CASE DEFINITION

Confirmed Case

Clinical illness* with laboratory confirmation of infection:

  • Detection of VZV DNA by polymerase chain reaction (PCR) in an appropriate clinical specimen**

OR

  • Seroconversion or significant change between acute and convalescent varicella-zoster IgG titre by any standard serologic assay in the absence of recent administration of any blood product or immunization with varicella vaccine.

OR

  • Isolation or direct antigen detection of varicella-zoster virus (VZV) from an appropriate clinical specimen**

OR

Clinical illness* in a person with an epidemiological link to a laboratory-confirmed case of varicella (chickenpox) or VZV (shingles) infection.

Probable Case

Clinical illness* in the absence of laboratory confirmation or epidemiological link to a laboratory-confirmed case.

Confirmed Case – Congenital

Any still born or neonate (a newborn up to and including 28 days of age) who has clinical evidence* of congenital varicella syndrome AND

  • History of mother with confirmed or probably primary varicella infection in the first 20 weeks of pregnancy

OR

  • Laboratory confirmation of varicella infection in the absence of maternal confirmation of primary varicella infection in the first 20 weeks of pregnancy.

Confirmed Case – Neonatal

Clinical illness* with laboratory confirmation*** of varicella infection in a neonate whose mother develops varicella rash from five days before to two days after delivery.

*Clinical illness: See clinical presentation in Alberta Public Health Disease Management Guidelines: varicella (chicken pox).

**Appropriate clinical specimens include swab from fresh lesion, CSF, or eye fluid aspirate.

Note: As of 2019, Alberta Precision Laboratories discontinued IgM antibody testing for varicella zoster virus (VZV) and names molecular testing (NAT) for VZV from suspected primary varicella infections (chicken pox) or varicella zoster cases (shingles) as preferable and the most sensitive and specific test for VZV.

REPORTING

All HCPs must follow the NWT Public Health Act. Measures for contact tracing and legislative requirements are laid out within the Reportable Disease Control Regulations and reporting timelines are found in the Disease Surveillance Regulations.

Note: the only acceptable methods of reporting to the OCPHO are outlined below. Information provided outside of these methods will not be considered reported unless otherwise stated by a CPHO delegate.

Health Care Professionals

For Part 2 written report within 24 hours

  • Confirmed and probable cases are to be reported to the Office of the Chief Public Health Office (OCPHO) within 24 hours after diagnosis is made or opinion is formed by completing the Communicable Disease Report Form then submitting to Communicable Disease Control Unit (CDCU) via secure medical fax 867-873-0442 or Secure File Transfer CDCU@gov.nt.ca. 
  • If there are any updates regarding the case or contacts the appropriate form will need to be resent with the additional information
  • Immediately report all outbreaks or suspect outbreaks by telephone (867) 920-8646 to the OCPHO

Laboratories

  • Report all positive results to the OCPHO by fax (867) 873-0442 within 24 hours

PUBLIC & HEALTH PROFESSIONAL EDUCATION

For more information on varicella (chicken pox):

EPIDEMIOLOGY