Measles Update: Information for Physicians

Tuesday April 9, 2019

Recent travel-related cases of measles involving residents of Ottawa may lead to concerns among some of your patients.

In Ottawa, immunization coverage against measles is high (approximately 95% among school-aged children). Measles vaccines provide good immunity: ~85-95% of children will develop long-lasting protection against measles from the first dose of vaccine; close to 100% of children will have developed immunity to measles after the second dose. In a well-immunized population (95% or more of school-aged children) an introduced case of measles usually does not lead to an outbreak (for each case, only about 50% to 80% of the time will there be a single additional case), unless a subgroup of the community is involved in which children are unimmunized.

Here are some pointers concerning the prevention and investigation of measles:

Ensure that patients’ immunizations are up to date

  • The Ontario routine vaccination schedule (PDF) recommends that MMR be given after the age of 12 months, and then MMRV between 4-6 years.
  • If the child is travelling internationally to areas where measles is circulating, an initial dose of MMR can be given as early as 6 months; however, 2 additional doses of measles-containing vaccine must be administered after the child is 12 months old to ensure long lasting immunity to measles.
  • Adults born after 1970 may be under-immunized, having received only one MMR in childhood. If documentation of two measles-containing vaccines after 12 months of age is not available, immunization with MMR is recommended (without first checking serology for immune status).
  • Although most adults born before 1970 are considered to be immune, there are several populations who require immunization:
    • Travel: Those born before 1970 who plan to travel outside North America require one dose of MMR to be considered immune.
    • Students in post-secondary educational settings born before 1970 require one dose of MMR to be considered immune.
    • Health care workers require either 2 doses (after 12 months of age) of measles-containing vaccine, laboratory confirmed measles illness, or measles serology to prove immunity.
    • Members of the military require either 2 doses (after 12 months of age) of measles-containing vaccine, laboratory confirmed measles illness, or measles serology to prove immunity.
    • More details regarding requirements for immunity in special populations can be accessed in the Canadian Immunization Guide (Measles Vaccine: Table 1).
  • Measles vaccine precautions and contraindications can be found in the Canadian Immunization Guide.
  • Call 613-580-6744 x24224 from Monday to Friday 8:30 am to 4:30 pm or dial 3-1-1 after hours and ask for the Public Health Inspector on call. Ottawa Public Health will explain testing requirements and requirements for isolation of the patient. We will need the patient’s symptoms, date of onset of symptoms, exposure history, travel history (if any in previous 21 days), and vaccination history.
  • Measles is airborne, so please mask any patients with fever and rash immediately upon arrival, place them straight away into an examining room, schedule them preferably at day’s end, and do not use the room for other patients for 2 hours.

Report any suspected cases of measles immediately to Ottawa Public Health by telephone

Measles Clinical Presentation

Typical symptoms of measles include a prodrome with fever, cough, conjunctivitis, coryza, and, possibly, small spots with white centres on an erythematous base on the buccal mucosa (Koplik’s spots). After 3 to 4 days (sometimes longer if immunocompromised) a maculopapular (blotchy) rash appears, first on the face and behind the ears then spreading to the trunk and limbs. While the rash in measles can be indistinguishable clinically from other causes of maculopapular rashes, the timing of evolution of the symptoms can help distinguish measles from other viral rashes.

Testing for measles

Laboratory testing is required for any suspect case of measles and must include both acute serology and virus detection by PCR. 

Virus Detection by PCR:

  • A nasopharyngeal swab or aspirate, or a throat swab, should be obtained within 7 days after the onset of rash. Specimens should be collected typical viral collection kit containing pink medium (the same kit that one would use for other common viral diagnostics such as HSV). 

AND

  • Approximately 50 mL of clean catch urine should be collected in a screw top sterile container within 14 days after the onset of rash.

Acute Serology

A blood specimen for measles antibodies, IgM and IgG, should be collected ideally within 7 days after the onset of the rash.

Convalescent Serology

Convalescent serology is recommended only if acute serology and virus detection are negative or indeterminate.  A convalescent blood specimen should be collected 7 to 10 days after the acute sample.  The requisition should specify that the blood specimen is for "convalescent measles serology".

Please contact OPH for facilitation of all measles testing. Additional laboratory testing information is available at the Public Health Ontario website at www.publichealthontario.ca/measles.

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