Three diseases humanity said we'd conquered, but haven't
In this photo released by UNICEF, a health worker administers polio vaccine to a child as part of a UNICEF-supported vaccination campaign at the Abou Dhar Al Ghifari Primary Health Care Center in Damascus, Syria, Tuesday, Oct. 29, 2013. (UNICEF / Omar Sanadiki)
Angela Mulholland, CTVNews.ca
Published Thursday, March 6, 2014 10:04AM EST
Last Updated Thursday, March 6, 2014 10:18AM EST
Ottawa Public Health’s confirmation this week of the region’s first lab-confirmed case of measles since 2011 is yet another reminder that while there are diseases many Canadians haven’t seen up-close for years, many of them have not been eradicated at all and continue to infect thousands of people around the world.
Here’s a closer look at just three of them:
At one time, measles was common in Canada, but the disease has been rare since the introduction of a vaccine in 1963. But measles is far from eradicated globally, leading to tens of thousands of deaths a year. In 2012 alone, there were about 330 measles deaths each day around the world, mostly in children, says the World Health Organization.
In Canada, the Public Health Agency of Canada says there have been no indigenous cases since 1997, although a dozen or so cases are imported here annually from travellers.
But recent years have seen a number of large outbreaks, including one in Quebec in 2011 that led to more than 725 infections. That outbreak is believed to have begun with a single Canadian bringing the illness back from Europe. An outbreak in 2010 in British Columbia led to 82 cases, and Alberta saw its own cluster of 42 confirmed cases between October, 2013 and January of this year.
Measles is still considered one of the most easily transmitted diseases in the world; in fact, it’s so contagious, the U.S. Centers for Disease Control says any unimmunized child exposed to it will probably become infected. But due to misinformation and overblown fears about vaccines, measles vaccination rates have been dropping over the last 20 years. That’s led many global health experts to warn that, until vaccination rates rise, outbreaks of the disease will continue.
When one thinks of plague, it’s the Black Death pandemic in Europe of the Middle Ages that comes to mind. That outbreak killed a stunning 75 to 200 million people – or approximately half of the European population.
But the plague didn’t vanish after that pandemic. In fact, there have since been a number of plague outbreaks around the world, including several in the last two centuries.
Many blame rats for causing plague, but in fact the disease is caused by a bacterium that lives in the fleas carried on rodents. And that bacterium continues to thrive.
The World Health Organization says it fields reports of between 1,000 and 2,000 cases each year, though the real number of unreported cases is likely much higher.
The southwestern U.S. sees an average of 7 human plague cases a year, though some years have seen as many as 17. Here in Canada, the bacterium lives in ground squirrels and mice throughout the southern Prairies, but the Public Health Agency of Canada says human cases of plague are rare. The last case reported in 1939.
Today, modern antibiotics can treat plague if they’re taken early enough in the infection.
Not long ago, polio was one of the most feared diseases in the world, paralyzing thousands of children a year. To this day, there remains no treatment or cure for the virus spread mostly through contaminated water, as well as person to person.
But the introduction of an effective polio vaccine in the middle of the last century changed everything, allowing the disease to finally be brought under control.
Today, polio has been eliminated from most countries, including Canada. Our country hasn’t seen a homegrown case since 1977.
A massive global effort began in 1988 to eradicate the disease, allowing for the vaccination of 2.5 billion children. Since then, polio cases have dropped by 99 per cent -- from an estimated 350 000 cases to just 223 reported cases, in 2012.
However, infections continue. In three countries -- Afghanistan, Nigeria and Pakistan -- polio still occurs regularly. In India, the country has not a reported case for three years, though with poor sanitation and a dense population, the country is at high risk of new outbreaks.