For Health Professionals Measles Epidemiology Outbreak Summary Public Health Actions Past Updates Measles Vaccine Canadian Immunisation Guide General Information

Links to Resources

Information for Health Professionals

Updated: November 14, 2007

Measles

Measles (rubeola) is a leading cause of vaccine-preventable deaths in children worldwide. There has been a marked reduction in incidence in countries where vaccine has been widely used, but measles remains a serious and common disease in many parts of the world. Complications such as otitis media and bronchopneumonia occur in about 10% of reported cases, even more commonly in those who are poorly nourished and chronically ill, and in infants < 1 year of age. Measles encephalitis occurs in approximately 1 of every 1,000 reported cases and may result in permanent brain damage. Measles infection causes subacute sclerosing panencephalitis (SSPE), a rare but fatal disease. In developed countries, including Canada, death is estimated to occur once in 3,000 cases. Measles during pregnancy results in a higher risk of premature labour, spontaneous abortion and low birth weight infants. Canada has made great progress in its goal of measles elimination, and endemic transmission of measles has been interrupted.

Epidemiology

Before the introduction of the vaccine, measles occurred in cycles with an increasing incidence every 2 to 3 years. At that time, an estimated 300,000 to 400,000 cases occurred annually. Since the introduction of vaccine, the incidence has declined markedly in Canada (see Figure 8). Between 1989 and 1995, in spite of very high vaccine coverage, there were many large outbreaks involving mainly children who had received one dose of measles vaccine. It was estimated that 10% to 15% of immunized children remained unprotected after a single dose given at 12 months of age, a proportion large enough to allow circulation of the virus. These primary vaccine failures were mainly caused by the interference of persisting maternal antibody. The currently recommended second dose aims to achieve immunity in children who did not respond to their first dose.

In 1996/97, every province and territory added a second dose to its routine schedule, and most conducted catch-up programs in school-aged children with measles or measles/rubella vaccine. These interventions achieved vaccine coverage for the second dose in excess of 85%, reducing the proportion of vulnerable children to such a negligible level that viral transmission could not be sustained.

Measles elimination within a population should be possible, as an effective vaccine is available and there is no non-human reservoir or source of infection. During the XXIV Pan American Sanitary Conference in September 1994, representatives from Canada and other nations resolved to eliminate measles in the Americas by the year 2000. In Canada, sustained transmission has been eliminated by our current schedule and high vaccine coverage. However, as expected, imported cases continue to occur. Secondary spread from these imported cases is self-limited and involves the few Canadians who are still vulnerable. The largest outbreaks have occurred in isolated groups that are philosophically opposed to immunization. Nevertheless, there is very limited secondary transmission of measles in the general population. Between 2002 and 2006, the number of measles cases reported annually ranged from 6 (2005) to 16 (2003) with a yearly average of 10.

Most other countries in North, Central and South America have also succeeded in eliminating sustained transmission. In 2005 fewer than 100 measles cases were reported in all of the Western Hemisphere. The situation in other regions is evolving at a slower pace, though measles deaths in Africa have been reduced by 60%, largely through the efforts of The Measles Initiative, a cooperative group led by the Red Cross, in partnership with UNICEF, the Centers for Disease Control and Prevention, the World Health Organization and the United Nations Foundation.

The greatest challenge for future years will be to continue achieving vaccine coverage rates of 95% or more as measles becomes increasingly unfamiliar to Canadian parents. Immunization against measles will continue to be necessary in Canada until global elimination of the disease has been achieved.

Source: Canadian Immunization Guide, 7^th edition, 2006

Update on Measles Outbreak in Quebec
Outbreak Summary (week starting November 4, 2007)

Increased measles activity is currently being investigated in 7 out of 18 health regions in Quebec. As of the week starting November 4, 2007, no new reports result in a total of 95 confirmed cases of measles (Table 1). A confirmed case meets one of two criteria: (i) laboratory-confirmation of measles infection OR (ii) clinical compatibility with measles infection and an epidemiologic link to a laboratory-confirmed case. Only confirmed cases which meet this national case definition are being counted and reported. Probable and suspect cases still need to be identified for prompt and appropriate medical and public health management (e.g. diagnosis, specimen collection, laboratory testing, clinical care, as well as public health reporting, follow-up and intervention).

Table 1: Age and Sex Distribution of Confirmed* Measles Cases Reported in Quebec(N=95, week starting November 4, 2007)

The first reported case had rash onset the week of April 15, 2007. The date of onset is known for all cases (Figure 1). Where immunization status is known, nearly all of the cases reported in Quebec (79/86) are susceptible individuals who are under-immunized (i.e. 1 dose of measles vaccine) or not immunized at all. In the latter case, these are mainly individuals who oppose vaccination for philosophical reasons. Ten cases have been hospitalised and to date, no serious complications have been reported. 

Figure 1: Confirmed* Measles Cases Reported in Quebec, Weeks starting April 15, 2007 - November 4, 2007 (N= 95)

* A confirmed case is either a laboratory-confirmed case OR clinically compatible and linked to a laboratory-confirmed case.

Several community exposure settings have been identified through contact tracing. They include a fashion event, a national conference with participants from around the world, a theatrical event, two elementary schools with sub-optimal vaccination coverage rates, a public swimming pool as well as public transit and two workplace settings. Full public health follow-up and intervention is underway in all identified exposure settings. To-date, no known cases of measles related to the outbreak in Quebec have been reported in any other provinces or territories.

Laboratory Testing
Virus genotyping identifies and aids the global tracking of circulating measles virus strains. Genotyping can also be used to help link cases to clusters and to provide evidence that indigenous transmission has been eliminated. The National Microbiology Laboratory has identified a second D4 strain associated with outbreak in Quebec, likely representing a second importation.

Public Health Actions

Public health authorities in Quebec are actively searching for and managing cases as well as tracing contacts and offering vaccination or immune globulin as required. Authorities continue to advise the public of the on-going measles activity and are encouraging individuals to update their immunization, if necessary.

Public health and primary care providers should remain vigilant in the detection, appropriate testing and public health follow-up of febrile rash illness. Any suspect measles cases, particularly those with travel history to areas with endemic or epidemic measles, should be reported as soon as possible through the regular channels.

Public health and primary care providers are encouraged to refer to their local or provincial/territorial ministry of health for specific recommendations on action that may be required within their jurisdiction.

All provinces and territories have been informed of the epidemiologic situation and the public health management strategies in the affected jurisdiction. As such, all jurisdictions are encouraged to remain vigilant in monitoring for measles activity within their regions and report any cases to the Public Health Agency of Canada, through Canada's weekly enhanced measles surveillance system.

The Public Health Agency of Canada is notifying appropriate authorities in the event of exposure settings involving inter-jurisdictional or international travel and/or in the event of cases known to have traveled while infectious.

The Public Health Agency of Canada will continue to provide updates and work with the affected province by providing technical advice and assisting with laboratory testing of clinical specimens at the National Microbiology Laboratory.

The Public Health Agency of Canada encourages parents, guardians and adults to maintain up-to-date immunizations for themselves and their children, and encourages susceptible individuals to be immunized in accordance with the National Advisory Committee on Immunization (NACI) guidelines. All guidelines can be accessed at: www.naci.gc.ca. As a small proportion of adults born since 1970 are still vulnerable to measles, to minimize the risk of measles exposure, NACI currently recommends a second dose of the measles, mumps and rubella (MMR) vaccine for certain adults born after 1970. This includes students at post secondary institutions and health care workers.

Links to Resources

Santé et services sociaux Québec – public information
http://www.msss.gouv.qc.ca/sujets/prob_sante/rougeole/rougeole.php

Canadian Immunization Guide, 7th edition
http://www.phac-aspc.gc.ca/publicat/cig-gci/index.html

National Microbiology Laboratory – Guide to Services
http://www.nml-lnm.gc.ca/english/guide/default.asp

Immunizations recommended for travel outside of Canada
http://www.phac-aspc.gc.ca/tmp-pmv/236_e.html

Canadian National Report on Immunization, 2006
http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/06vol32/32s3/index.html#toc

Guidelines for Control of Measles Outbreaks in Canada
http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/96vol22/dr2202ea.html

Measles Surveillance: Guidelines for Laboratory Support
http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/98vol24/dr2405ea.html

Consensus conference on measles. Canada Communicable Disease Report, 30 May 1993; 19-10: 72-9.

National Advisory Committee on Immunization Statement on Elimination of Indigenous Measles in Canada. Canada Diseases Weekly Report, 23 Feb 1980; 6-8:33-9.

Measles Elimination in the Western Hemisphere and Global Perspective. Journal of Infectious Diseases 2004; 189(Suppl 1): S227-57.

Measles Update/Update-Vaccine Preventable Diseases
http://www.phac-aspc.gc.ca/publicat/uvpd-mjmepv/vol7-3/index.html

Photo archive
http://www.phac-aspc.gc.ca/publicat/uvpd-mjmepv/photos_e.html

Global Measles Initiative
http://www.measlesinitiative.org/index3.asp

Measles Mortality Reduction and Regional Elimination: Strategic Plan 2001-2005 www.who.int/vaccines-documents/DocsPDF01/www573.pdf

Measles Elimination Field Guide, 2nd edition 2005 (PAHO) www.paho.org/english/ad/fch/im/fieldguide_measles.pdf

Pan American Health Organization, Measles/Rubella Weekly Bulletin
http://www.paho.org/english/ad/fch/im/MeaslesWeeklyBulletin.htm

Global measles and rubella laboratory network – update http://www.who.int/wer/2005/wer8044/en/index.html