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Lecture 10

HLTB21H3 Lecture Notes - Lecture 10: Hemagglutinin, Headache, Reverse Transcriptase


Department
Health Studies
Course Code
HLTB21H3
Professor
Caroline Barakat
Lecture
10

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HLTA01 Lecture 10 Notes Thursday, November 22nd, 2012
1918 Influenza/HIV - AIDS
1918 Influenza
History
Origin of cause is unknown
Hippocrates: first record of an influenza pandemic in the year 412 B.C.
Three main pandemics of influenza existed in the 16th, 18th, and 19th century
o About 30 pandemics have occurred since the 1500s
o Occurs about three times in a decade, roughly
Since 1580, there have been thirty-one additional flu pandemics recorded
Spanish Flu (1918 - 1919):
o Origin of name: Not because it was originally from Spain but because there was no
censorship in Spain in relation to the pandemic that occurred (were really open about
number of cases and etc)
o Approximately 50 M deaths worldwide in less than 2 years
o 500,000 death in the US (19,000 in New York City)
o 300,000 cases in Ontario - 8700 death (1200 deaths in Toronto in just 3 weeks)
o 500,000 cases and 14,000 deaths in Quebec
Occurred after WW1
Affected the younger population more than the older population, which is bizarre compared to
other flues
Cities like Boston had prevention such as mouth masks to prevent the spread of the Spanish Flu
o In some cases were fined if you didn’t
o Until 1940s-1950s, not much was known about the cause of influenza
Reason behind so many preventative measures
H1N1 strain Connected to Swine Flu
Symptoms
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

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HLTA01 Lecture 10 Notes Thursday, November 22nd, 2012
1918 Influenza/HIV - AIDS
Figure 1:
o Differentiation between Influenza flu and the common cold
Etiology
Level 10 flu: If no preventative measures are taken, can infect 10 others around them with the
Influenza virus
3 types of influenza virus: Influenzavirus A (most virulent), B, &C
Influenza A and C infect multiple species, while influenza B almost exclusively infects humans
o Influenza B and C are more commonly linked to epidemics that occur (least virulent)
Influenza A virus has 8 genes
o Has genetic instability, can mutate very easily
o Has a very short incubation period: 1-2 days
o Can easily be transmitted from one individual to another
o Spread by droplets; each droplet contains about 50,000-500,000 virus particles
New and virulent (Influenza A virus) flu strains are produced mainly from the effects of two
surface proteins
o Hemagglutinin (H) critical to virus entry into cell (the gate to enter)
o Neuraminidase (N) allows virus to leave host cell after replication and move from cell
to cell (the exit)
There are over 15-16 H’s and 9 different N’s in bird flu viruses
o Different combinations of H’s and N’s cause different strains
Flu virus from birds - unable to replicate well in humans unless they move to an intermediate
host: chickens, geese, ducks
o Since they can fly, can spread virus more efficiently
o Pollute waterways with feces birds use the water to bath and drink from become
infected
o Chickens die off quickly due to infection, while pigs are more resistant and can survive
for some time

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HLTA01 Lecture 10 Notes Thursday, November 22nd, 2012
1918 Influenza/HIV - AIDS
o Figure 2:
Specific to the H5N1 strain (Avian flu)
o Figure 3:
Flu genes of birds, pigs, humans can mix and produces new strains
Antigenic drift:
Random mutations that change the genes causing the virus to change
Figure 4:
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