Three more cases of measles diagnosed in B.C.; What is measles?
Posted Apr 07 2010 12:00am
KELOWNA, B.C. — Three cases of measles have been confirmed in the B.C. interior on the heels of a outbreak last month in the Metro Vancouver area. The Interior Health Authority says the three cases are in Vernon, Lillooet and Williams Lake.
One has been traced back to overseas exposure but health officials say the other two people hadn't travelled outside their communities. That means they can't be traced back to the measles outbreak in the Vancouver area, in which there were 10 confirmed cases of the disease, eight of them from a single household.
The B.C. Centre for Disease Control said at the time it suspected two international visitors brought measles into Vancouver sometime in February - while the Olympics were on - or in early March.
None of the people who've got sick in either outbreak were fully immunized and health authorities are urging parents to make sure their children's vaccinations are up to date.
The virus is transmitted by airborne droplets (sneezing or coughing) or direct (close personal) contact with nasal or throat secretions of infected persons. Less commonly, the virus spreads through contact with articles freshly soiled with nasal and throat secretions.
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 under 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.
The virus can be spread for about four days before and until about four days after rash onset. Health officials have implemented a public information campaign to advise patients, the general public and health care providers on the appropriate control measures. People experiencing measles symptoms are advised to call before going to a doctor's office or clinic as a precaution to assist health care providers in preventing further spread of the disease.
Measles is a vaccine-preventable disease. Canadians are reminded to keep all vaccinations up-to-date. Two doses of measles/mumps/rubella (MMR) vaccine are recommended for children. One dose administered on or after the first birthday; the second dose should be given after 15 months of age but before school entry.
A second dose of MMR vaccine is also recommended for Canadians at greatest risk of exposure; for example, travellers to measles-endemic areas, healthcare workers, military recruits and students at post-secondary institutions. Speak to your health care provider regarding the status of your immunization.
During the XXIV Pan American Sanitary Conference in September 1994, representatives from Canada and other Pan American Health Organization nations resolved to eliminate measles in the World Health Organization region of the Americas. Shortly thereafter, in 1995, Canada's Conference of Federal/Provincial/Territorial Deputy Ministers of Health endorsed a national goal of measles elimination.
Nationally, sustained transmission has been eliminated by the current 2-dose measles immunization programs and high vaccine coverage in the general population. The 2004 National Immunization Coverage Survey (NICS) estimates that 94% of two year-olds have received one dose of measles vaccine and that 79% of seven year-olds have received at least two doses.
Epidemiological and virological evidence suggests that endemic transmission of measles has been mostly interrupted since 1998; however, as expected, imported cases continue to occur. Secondary spread from these cases is usually self-limited and involves the few Canadians who are still vulnerable due to under-vaccination or opposition to immunization.
Canada has had national, active measles surveillance in place since 1998. All provinces and territories report confirmed cases of measles weekly to the Public Health Agency of Canada who in turn report weekly to the Pan American Health Organization.
Over the past five years, there has been an average of 10 measles cases each year in Canada with clusters of approximately 4 cases. The last large outbreak happened in the year 2000. It was centred in Alberta and involved nearly 200 individuals; nearly all of them un-immunized for religious or philosophical reasons. The initial cases were imported from Mexico and Bolivia.
As of the week starting 23 December, 2007, there were 101 measles cases reported in Canada in 2007: Quebec (95), Alberta (3), and British Columbia (3).