This past week, students at BCIT in Burnaby were exposed to measles and a few came down with the disease.
Measles is a highly contagious, serious disease caused by a virus and one of the leading causes of death amount young children, according to the World Health Organization. This is despite the fact that there is a simple, safe, and cost-effective vaccine available.
In 2012, there were 122,000 measles deaths globally which works out to around 330 deaths each and every day. In one sense, it is not a lot people as there were slightly more than 58 millioon deaths that year.
On the other hand, they could be considered unnecessary deaths as a vaccine is readily available. Certainly for the families involved, they represent a tragedy.
This is why the measles outbreak in Burnaby is so significant. Surely, in a rich country like Canada, vaccination should have eradicated the disease. Why would we need to worry? Measles don't affect us. At least that is a popular belief.
Unfortunately, it is not true. We do not eradicate diseases. We control them. By vaccinating a large percentage of the population against a particular pathogen, we ensure that the disease is managed in a manner that prevents outbreaks or epidemics.
Measles is a well-managed disease. Outbreaks have been rare over the past half century. Most measles deaths occur in underdeveloped countries that do not have adequate health care systems or the financial means to provide the vaccine to the population.
But the virus is still present in our population.
The protective benefit of a large percentage of the population being vaccinated is called herd immunity. It provides a measure of protection for individuals who have not developed immunity, who have compromised immune systems, or who have not been vaccinated.
The spread of any viral or bacterial disease is dependent upon having a suitable host to accept the disease. In the case of an immunized herd, any individual that contracts the disease cannot pass it on. It is difficult for a disease to spread.
However, if the percentage of a population that are not vaccinated declines, then the disease can once again gain a foothold and a large number of individuals can become infected. An outbreak results and if bad enough, a full blown epidemic might occur.
In the case of measles, herd immunity requires somewhere around 95 per cent of the population to be vaccinated. When the disease was common and running rampant through populations in North America half a century ago, getting a vaccine was a common occurrence. It was a simple Public Health measure.
No one thought twice about it. Indeed, a very effective vaccine against mumps, measles, and rebulla was developed and administered. The decline in measles in the North American population has been dramatic.
It is mirrored by more recent work where one billion children in high risk countries have been vaccinated since 2000. As a consequence, the annual death toll from measles has dropped from 564,400 to 122,000 and it will continue to decline as the herd immunity takes hold in these countries.
However in North America where the disease is well controlled, the perception is that the disease has been eradicated and vaccination is no longer necessary. It has been suggested by Public Health officials that only 60 per cent to 65 per cent of children are being vaccinated and, as a consequence, the disease is on the comeback.
In some communities, 100 per cent of the children are not being vaccinated resulting in widespread outbreaks of the disease. It is through one of these communities that students at BCIT were thought to have been exposed.
The other side of the issue is that measles typically only kills 1 in 3,000. That is, 99.97 per cent of the people exposed suffer through the effect of the disease but after a couple of weeks, they recover and have gained a measure of immunity. Measles just doesn't feel like a killer disease. More like a bad case of the flu.
This is due, in part, to the effectiveness of modern Public Health measures that have seen many of the diseases that used to run rampant controlled. Diphtheria, whooping cough, scarlet fever, and polio do not result in massive outbreaks and widespread epidemics. For the most part, we have controlled these diseases.
The consequence is that our average life expectancy has increased dramatically - to 81.5 years old in Canada - so that we now end up dying of diseases such as coronary heart disease and stroke. But that is a different story.
Unfortunately, as the childhood diseases of 50 years ago fade from our collective memories and we forget what it was like to have children dying from the measles, it is harder and harder to convince parents that a vaccination is the best way to ensure that their children are safe.
