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HLTB21H3 Lecture Notes - Influenza Vaccine, Influenza A Virus Subtype H7N7, Influenza A Virus Subtype H7N3

Health Studies
Course Code
Caroline Barakat

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Lecture 10: 1918 Influenza / HIV - AIDS
Influenza - history
-Hippocrates - record of an influenza pandemic in the year 412 B.C.
-Since 1580, there have been 31 additional flu pandemics recorded
-Spanish flu of 1918 1919
-Spain did not censor how much it impacted the humans
-Approximately 50 M deaths worldwide in less than 2 years:
- 500,000 death in the US (19,000 in New York City)
- 300,000 cases in Ontario - 8700 death (1200 deaths in Toronto in just 3 weeks); 500,000 cases and 14,000
deaths in Quebec
-Fever, chills, headache, weakness and fatigue as well as coughing, sneezing, runny nose (coryza)
-Residual cough and tiredness lasts up to 6 weeks
-Complications can include ear infections, pneumonia, dehydration and death
-distinctive feature to flu= fever & extreme exhaustion/ fatigue; cold= rare
-3 types of influenza virus: Influenza virus A (most virulent), B, &C (sporadic epidemic between children/young adults)
-Influenza A virus has 8 genes
1) genetically unstable
2) Short incubation period 1-3 days
3) Ease of transmission
-Spread by droplets each droplet contains 50,000 500,000 virus particles
-New & virulent flu strains are produced from the effects of 2 surface proteins
-Hemagglutinin (H) critical to virus entry into cell
-Neuraminidase (N)allows virus to leave & move from cell to cell
-There are over 15 H’s and 9 different N’s in bird flu viruses
-enters humanscommon among aquatic animals carry influenza in intestine use waterways and excrete feces and if
other animals (intermediate host) come into contact with contaminated water, get influenza virus
-Virus cannot replicate well in humans unless it moves to intermediate hostusually domestic fowl (chicken, geese,
ducks or pigs)
-Flu genes of birds, pigs, humans can mix and produces new strains
Antigenic drift
-humans cannot build immunity
-Random mutations that change the genes causing the virus to change
-Occurs globally, year-round
-Serotypes that have been confirmed in humans (ordered by the number of known human pandemic deaths):
-H1N1 - ‘Spanish Flu’ (refer to end of 2nd paragraph, p. 398 of course textbook)
-H2N2 - ‘Asian Flu
-H3N2 - ‘Hong Kong Flu’
-H5N1 - pandemic threat
in 20078 flu season
-H1N2 - endemic in humans and pigs
-H9N2, H7N2, H7N3, H10N7
Mode of Transmission
Respiratory Droplets - coughing, sneezing or talking
Direct Contact from the hands of an infected person
Indirect Contact - by touching surfaces or objects contaminated with the virus
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