Infectious Disease
Bird Flu Today Public Awareness Campaign - Teacher’s Section
 Background Information for Teachers
Influenza viruses are divided into A, B, and C groups based on their virulence, with A being the mildest and C being the most virulent. Most seasonal influenza viruses fall under the A category, but viruses are always evolving . These viruses are further classified into subgroups based on exterior proteins called hemagglutinin (H) and the neuraminidase (N). The 2007 subtypes currently circulating are both type A viruses; H1N1 and H3N2. “Influenza type A viruses undergo two kinds of changes. One is a series of mutations that occur over time and cause a gradual evolution of the virus. This is called antigenic “drift.” The other kind of change is an abrupt change in the hemagglutinin and/or the neuraminidase proteins. This is called antigenic “shift.” In this case, a new subtype of the virus suddenly emerges. Type A viruses undergo both kinds of changes; influenza type B viruses change only by the more gradual process of antigenic drift.”[4]
In 1918, as World War I was coming to an end, a flu pandemic was just beginning the United States. The pandemic was caused by a shift in the H1N1 strain of the flu virus. [6] By the end of the epidemic, over 675,000 Americans were dead. [1] In all, the pandemic killed more than 50 million people worldwide. [2] Although the origin of the disease is still under dispute, one theory indicates that it may have started in human then transferred to swine and then back again. [3] Symptoms experienced by the 1918 flu victims are quite similar to those of people who have contracted H5N1 today – including typical influenza symptoms, eye infections, pneumonia, and severe respiratory diseases, among others. [1] The 1918 pandemic was not the only flu pandemic in the last century; there were also pandemics in 1957 and 1968. Today, the flu virus continues to mutate and number of new strains have become prominent between 1977 and 2004. [6]
Today’s H5N1 virus has been transferred to humansmainly through human contact with the excretions or secretions of domesticated poultry. [1] Currently, the virus cannot be easily transmitted from person to person. Scientists fear that if H5N1 did develop ability to be transmitted between human beings, it could lead to another global pandemiceven worse than that of 1918, given today’s global society. To evolve the ability to “jump” from human to human, the virus would probably require an intermediate host to facilitate the process. For example, an H5N1 virus would have to infect a pig that is also infected with a human influenza A virus. This would allow for mixing of the genetic material of both viruses, possibly resulting in a form that could be transmitted between humans. [7]
Every year vaccines are developed to fight the currently pervading virus strains. [4] Certain target groups such as young children or the elderly are encouraged to get the vaccine annually to develop immunity tocurrent strains. There are also antiviral drugs available on the market that are used to treat and prevent influenza A viruses. [4] However, just as bacteria develop antibiotic resistance, so too can viruses develop antiviral resistance.
The purpose of this webquest is to engage students in thinking critically about how the American government should respond to a potential avian flu pandemic based on current knowledge about viruses, vaccines, microbial evolution, and public health measures. Participating students willpartake in both individual and team components of the webquest. As teams, they will use individual and group research to develop a public awareness campaign advocating their perspective.
Before beginning the webquest, students should have a solid understanding of the basic differences between viruses and bacteria, as well as their respective treatment and control measures. We recommend that you discuss the following discussion questions before starting the webquest.
1. What are the differences between viruses and bacteria?
See the KSM website, infectious diseases exhibit section on “Where are They?”
2. 2. What is the difference between an antibiotic, a vaccine, and an antiviral?
See the KSM website, infectious diseases exhibit sections on “Vaccines and Human Immunity” & “Antibiotics & Emerging Drug Resistance”
3. How many Americans die each year on average from the seasonal flu virus?
36,000 each year are killed and 226,000 are hospitalized
Influenza is the seventh leading cause of death in the US, when combined with pneumonia. [5]
If you choose not to use the webquest in its entirety, but would like to focus on the science topics consider dividing the class into groups, with each group investigating one of the four researchers’ topics’. Each group can then present their findings. However, to maximize real-world connections, we strongly recommend integrating the policy project component
If time permits students can gain an overall sense of the 1918 pandemic by watching the Public Broadcasting Service (PBS) DVD ”American Experience: Influenza 1918”.
[1] http://www.pandemicflu.gov/general/index.html
[2] http://www.pandemicflu.gov/general/historicaloverview.html
[3] http://www.cdc.gov/ncidod/EID/vol12no01/05-1254.htm
[4] http://learning.turner.com/efts/virus/fluvirus.htm
[5] http://www.facesofinfluenza.org/about.php
[6] http://www3.niaid.nih.gov
[7] http://www.cdc.gov/flu/avian/gen-info/transmission.htm
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