Measles, polio, diphtheria and the mumps are diseases that were once common in Canada, but are seldom seen today.

Those diseases do still exist, but we are much less vulnerable to contracting them thanks to routine childhood immunization.

Immunization works by introducing a small amount of antigen to create a memory in the body’s immune system. The immune system learns to recognize this disease without the person actually becoming ill. Later, if that same immune system comes in contact with the disease, the body is prepared to fight the disease off quickly.

When children are immunized, their bodies make antibodies or protection that fight specific infections. If they are not protected and come in contact with one of these infections, they may get sick and potentially experience complications or even, in rare cases, die.

Immunization offers protection for more than just the individual. Immunization protects communities by preventing the spread of disease—as more people are immunized, the risk of disease for everyone is reduced.

The challenge is to keep immunization rates high so that we won’t have future outbreaks of disease.

Whenever immunizations coverage rates drop, the window opens for a resurgence of disease. In 2005, for example, Oxford County in nearby southwestern Ontario experienced an outbreak of rubella (German measles) that resulted in 283 cases of rubella.

All but two of the individuals infected had not been immunized. Pregnant women exposed to rubella face an increased risk of having their babies born with congenital rubella syndrome, which can cause problems with their eyes, heart, hearing and neurologic and cognitive development.

In 2000, Ireland saw more than 1,200 cases of measles, compared with only 148 in the year before due to a decline in immunization rates. In the former Soviet Union between 1990 and 1995, approximately 125,000 cases of diphtheria resulting in 4,000 deaths were due to decreased public access to immunization.

Outbreaks like these are easy to prevent through routine childhood vaccinations. However, immunization isn’t just for children. Adults also need to be aware that they require a booster for tetanus and diphtheria every 10 years in order to be protected.

An annual influenza vaccine is recommended as well as the pneumococcal vaccine for those over 65 years or with certain high-risk medical conditions. There may also be vaccine recommendations for travel to countries outside of Canada. Remember to speak with your health-care provider to be sure you are up to date.

For more information and advice on immunizations that protect your children’s health call Your Health Connection Monday to Friday at 721-7520 (1-877-721-7520) and speak with a nurse or check the website, a link to which is provided.

• Dr. Colin Lee is an associate medical officer of health.