Measles & Rubella Weekly Monitoring Report - Week 21, 2017: May 21 to May 27, 2017

Key Points

  • In Canada, one new case of measles was reported in week 21, 2017.
  • One province (Nova Scotia) has active measles cases.
  • A total of 41 cases of measles, and zero cases of rubella have been reported in Canada in 2017.

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Epidemiological summary:

During epidemiological week 21, 2017 one new case of measles was reported in CanadaFootnote 1, by Nova Scotia. This case had rash onset in week 21, and was linked to an ongoing outbreak.  

To date in 2017, 41 cases of measles have been reported in Canada. Two outbreaks have been confirmed – one that began in February and has since concluded, and the other is an ongoing outbreak that began in March and involved four provinces.

No cases of rubella have been reported in 2017 (Figure 1). It has been 66 epidemiologic weeks since the last rubella case was reported (week 6, 2016).

Figure 1: Number of cases of measles (n=41) and rubella (n=0), by week of rash onset, as reported to the Canadian Measles/ Rubella Surveillance System (CMRSS) and Measles and Rubella Surveillance system (MARS), for the period ending May 27, 2017.

Geographic distribution

There are currently active* cases of measles reported in one Canadian province (Nova Scotia) (Figure 2).

There are no reported active cases of rubella in Canada (Figure not shown).

Maps from previous weeks, including any retrospective updates, are available online in the Measles and rubella weekly surveillance maps feature.

Figure 2: Distribution of active*, confirmed measles cases by health region

*Active cases or outbreaks are those in which the onset date of the most recent case/outbreak-associated case falls within 32 days of the issue date of this reportFootnote 2.

Laboratory summary

Measles

To date in 2017, 33 measles cases have been genotyped and the genotypes are B3 (n=6) and D8 (n=27) (Figure 3). Genotype information is pending for 2 additional cases.

During epidemiological week 21, 2017, 1 new measles genotype result became available. It was epidemiologically linked to an ongoing outbreak in Nova Scotia, and had a genotype D8 sequence identical to the index case which was imported from India.

Figure 3: Distribution of measles genotypes detected in 2017 (n=33) by week of rash onset.

Epidemiological weeks for laboratory specimens are assigned in accordance with WHO guidelines (WHO.WER.2012;9(87):73) with week 1 beginning on the first Monday of the year.

The current global distribution of measles genotypes can be found on the WHO Measles Surveillance website.

For information regarding the interpretation and use of measles genotyping (including a discussion of genotypes and sequence variants), refer to Hiebert J and Severini A. Canada Communicable Disease Report. 2014; 40-12: 257- 260.

Rubella:

To date in 2017, no rubella cases have been genotyped.

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2017-06-07