We can't let down our guard on disease control

Originally published in The Ottawa Citizen May 6, 2003
Original Title: Serious Assessment of Risk Syndrome

Times like these sharpen our attention to the frailties of life. The SARS outbreak illustrates the public perception of risk.When faced with a death rate of three to four per cent, we all want to be able to protect our family and friends from harm.

Public health officials judiciously and expediently enacted a containment process for SARS to limit the spread of the disease. The public must remain well-informed and vigilant. The downward trend of new SARS cases in Toronto attests to the importance of following quarantine guidelines.

People are naturally concerned about their risk of contracting the disease and succumbing to the infection. Many wonder if a vaccine is in the works or is even possible. ?

Throughout history, infectious diseases changed societies and rewrote geopolitical landscapes. In the 14th century, the Black Death (plague) decimated Europe, killing 25 per cent of its population and altering the course of its history. Smallpox, brought to the New World first by the Spanish conquistadors, destroyed the Aztec and Mayan civilizations. The French and British colonies followed suit, devastating the North American Aboriginal Peoples.

The last century is a testament to the work of thousands striving to protect us from the scourges of our time. History clearly shows how vaccines have saved millions of lives from the harmful effects of diseases that we no longer recognize. But these diseases remain among us. They have the potential to inflict great harm to our world if we become complacent and take their control for granted.

Our Canadian history of infectious disease can help us understand the risks of infection and cope with today’s realities. Try to identify these diseases. The answers are at the end of this column.

1. The most contagious severe viral infection in humans, this disease inflames the brain (encephalitis) in one out of every 1,000 infected people, often damaging the brain permanently. In Canada, before 1963 (the introduction of the vaccine), everyone contracted it before the age of 18. Epidemics occurred every two to three years; an average of 350,000 people infected yearly, 90 per cent under the age of 10. Each year it caused 50 to 75 deaths, 5,000 hospital admissions and 400 cases of encephalitis. Today there are fewer than 400 cases per year.

2. Another viral infection in circulation is mild in children but worse for teens and adults. Pregnant women, should they contract the disease, risk serious birth defects and potential fetal death. Eighty-five per cent of Canadians contracted this disease before age 20. Childbearing women were at greatest risk. In 1936, there were 69,401 cases. The vaccine has reduced this to about 2,000 cases per year. Local pockets of unvaccinated and partially immune people contribute to these remaining cases.

3. A strain of bacteria lurks ready to kill one in 10 infected Canadians (despite treatment) if we let our guard down as they did in the former Soviet Union. The bacterium produces a toxin that causes the throat to swell and forms a thick filmy membrane large enough to suffocate its victim. The toxin can damage the heart, kidneys and nerves.

The vaccine, developed in 1926, reduced the number of Canadian cases in 1924 from 9,000 to fewer than two to five per year since 1983.

4. In 1955, 7.6 million people from Canada, the United States, the former Soviet Union, Western Europe, Australia and New Zealand contracted a disease that permanently damages nerve cells in the spinal cord, leading to leg or arm paralysis and, in some cases, death.

About one in 100 suffering from the disease develops paralysis, and 76,000 people succumbed to this complication that year. The vaccine became available in 1955. By 1967, the number of cases for the year was 1,013 for those same countries, a reduction of more than 99 per cent. The last case in Canada was in 1989.

People respond to immediate threats. The aforementioned diseases were the SARS of their time: front-page diseases. Our senior citizens can attest to the fear and dread they felt when their children fell ill. They asked questions about treatment and vaccines then similar to those we ask now. ?

Common childhood infectious diseases are no longer on the front page because of vaccines and public risk-reduction strategies. These other diseases are by any reasonable standard worse than SARS — but our radar no longer registers these threats.

Indeed, some choose not to vaccinate their children. Some do not trust pharmaceutical companies, fear perceived vaccine side-effects or do not think there is any need to vaccinate given that the radar screen remains relatively clear.?

If we choose to be complacent about our social responsibility and forget about the reasons our children no longer face traumatic and life-threatening illness, we will face health risks greater than SARS.

Public health is not a fait accompli. It must be evidence-based, consistently applied throughout our society and accepted by everyone if it is to have an impact. There is justification to the public’s demand to ensure the safety of Canadians. Indeed, witness the latest hullabaloo about the lack of airport screening and thermal detection (fever) units to intercept potential SARS carriers.?

Refusal to vaccinate children and poor health screening procedures for refugees and immigrants for hepatitis B (300 million carriers) and tuberculosis (two billion people worldwide) put everyone at risk. It is akin to removing the airport screening systems and public health initiatives thereby increasing the community’s risk of illness. ?

Two 1998 studies in the Canadian Medical Association Journal support this argument. Foreign-born individuals, the majority emigrating from Asian countries, accounted for 70 per cent of the tuberculosis cases in Alberta over a five-year period. The average period between immigration to Canada and diagnosis was 11.2 years. A Montreal study reported similar findings. ?

There must be a consistent approach to disease prevention. It is not a boutique where we choose which diseases we wish to prevent.

Answers:? 1. Measles ?2. Rubella 3. Diphtheria ?4. Poliomyelitis

© Dr. Barry Dworkin 2003

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