The increase in the number of children attending schools in Canada and the potential for transmission of viral infection in that environment is a problem of great size. A virus is defined as "a morbid principle, or a poisonous venom, especially one capable of being introduced into another person or animal" in The Shorter Oxford English Dictionary. Due to their miniscule size, it was not until 1885 that Adolf Mayer observed their existence in the mosaic (leaf-spot) disease of the tobacco plant, which he described as to be caused by a strangely invisible contagious agent.1 This particular living entity was so small that it readily passed through a porcelain filter. With the invention of the electron microscope by Ernst Ruska, the virus' true anatomy was first time visible to us in 1933.2 They are so infinitesimal that billions could fit into a drop of water---or a drop of human blood. Viruses have the most exquisite ability to sense the right cell surfaces. They don't just cause diseases in people, they infect every form of life on earth. Some emerging viruses are very serious. Common examples are the hepatitis viruses, B and C. The hepatitis B pattern of illness was re

The prevalence of HBV in Canada is unknown, although some have estimated it to be about 0.5%-1.0%, however, this is just an educated guess.13 Furthermore, hepatitis B is not uniformly distributed in the community, as the prevalence in different ethnic or occupational, and other risk groups has not been well defined. Some specific population groups can be identified, in whom the prevalence is much higher than the national average. Most easily identifiable of these are immigrants from South East Asia and Africa, but other immigrant groups also have a higher than expected prevalence of the hepatitis B carrier.

Five to ten percent of hepatitis B young adult victims become chronic carriers, often without knowing it. However, nine of ten infants infected (90%) become chronic carriers. They are the group with the highest rate of risk to develop cirrhosis and liver cancer. The hepatitis B virus is globally distributed among humans. In a population with little immigration and emigration, childhood vaccination will eventually reduce the population pool of chronic HBV carriers. However, the continuous coming of immigrants into Canada, of whom the vast majority is from high-endemic countries, makes this strategy of inoculating elementary students lose the purpose. The bottom line is that the risk of chronic hepatitis is high before the age of five, and very low after the age of ten. Hence, if the vaccination program had been directed at new-borns instead of elementary schooled children, the end effectiveness of such an action would have justified the means.

One way of preventing the disease is to vaccinate against it. The package for inoculating against the disease consists of three shots. The usual schedule is: first injection, then a second one in 1 month, and a third one 5 months later. Children receiving the second and third injections may be given a combined vaccine that includes the Hib influenza type b, and HBV. This vaccine provides protection for at least 14 years, and possibly a lifetime. It will not "cure" a person who is already infected. The centres for Disease Control and Prevention recommend that all new-borns receive hepatitis B vaccine. Babies born to infected mothers should also receive hepatitis B immune globulin (HBIG) within twelve hours of birth. All children should be vaccinated by 11 years of age.

Many people with acute hepatitis B have no symptoms at al

Some common words found in the essay are:
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