Health An epidemic is when an outbreak of an infection develops suddenly among many persons in a localized community, country or even region. Epidemics of measles, for example, are common throughout the world in localized areas where vaccination rates are low. Ebola and SARS are examples of epidemics. A pandemic is declared when an outbreak of a contagious disease moves, often with unexpected escalation, from such localized areas or countries to the entire world. Epidemics and pandemics have afflicted disaster in all parts of the world over the centuries. The first documented evidence dates back more than 5,000 years ago in China, when an infectious disease ravaged a local community. Throughout the centuries, there have been infectious agents which have almost wiped out communities, countries and continents. For example, the Black Death in Asia and Europe from 1346-1353 − caused by a bacterium − is estimated to have killed more than half of Europe’s population. An epidemic in Mexico and Central America beginning in 1545 wiped out more than 15 million inhabitants. Those countries, along with South America and the Caribbean, were severely affected by the smallpox epidemic from 1520 to the 1600s, in which the death toll is reported to have been 56 million. In more modern times, we are reminded of the Spanish flu from 1918-1920 caused by an H1N1 virus which killed 40-50 million in just two years. The HIV/AIDS pandemic − especially prevalent in Sub-Saharan Africa and for which there is still no effective vaccine − has killed more than 25 million persons. The polio epidemic in North America, peaking in 1916 and lasting through to 1954, caused thousands of deaths and permanent disabilities. The Salk vaccine, discovered in 1954, was successful in preventing the disease and resulted in its eradication from North America by the late ‘70s…and now most of the world. Other more recent pandemics in our time have included the Asian flu in 1957-1958 and the swine flu pandemic in 2009-2010. Serious epidemics in our time have included the Zika virus epidemic and the Ebola epidemic, still associated with developing outbreaks with no vaccine yet discovered. A vaccine is defined as “a substance used to stimulate the production of antibodies and provide immunity against one or several diseases, prepared from the causative agent of a disease, its products, or a synthetic substitute, treated to act as an antigen without inducing the disease.” In the 1760s, Edward Jenner, an English apprentice surgeon, found that dairy farmers who had developed cowpox, a milder form of virus similar to smallpox, were immune from contracting the more disfiguring and lethal smallpox. From the skin pox of a milkmaid with active cowpox, he took a sample of material and injected it into an eight-year-old boy who had never had smallpox. Six weeks later, the boy was inoculated with material from a smallpox victim and he never developed smallpox. Considered the first vaccination, smallpox was eventually eradicated worldwide. Since that time, there have been numerous vaccines developed, many in our own lifetime. When I started practice, there was a vaccine for cholera and anthrax developed in the 1880s by Louis Pasteur. Polio, diphtheria, pertussis (whooping cough) and tetanus shots were given to all children in Canada. During my practice, four additional major vaccines were discovered including measles, rubella (Germanmeasles), chicken pox and mumps, all infectious diseases whichmost individuals born before the ‘60s had already suffered. Yet, still, there are some serious infectious diseases including malaria, HIV, herpes simplex, tuberculosis and gonorrhea for which no vaccine has been developed. CSANews | FALL 2020 | 49
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