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Lecture 10

HLTB21H3 Lecture Notes - Lecture 10: Rhinitis, Neuraminidase, Hemagglutinin


Department
Health Studies
Course Code
HLTB21H3
Professor
Caroline Barakat
Lecture
10

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History
-Hippocrates - record of an influenza pandemic in the year 412 B.C.
-Since 1580s, there ahve been 31 additional flue pandemics recorded
-Spanish Flu (1918-1919)
-Apprx. 50M deaths worldwide in less than 2 years
-500,000 death in the US (19,000 in NYC)
-300,000 cases in Ontario - 8700 death (1200 d in Tor. just 3 wks)
-500,000 cases and 14,000 deaths in Quebec
Symptoms
-Fever, chills, headache, weakness and fatigue as well as coughing, sneezing, runny nose
(coryza)
-residual cough and tiredness lasts up to 6 wks
-complications can include ear infections, pneumonia, dehydration and death
Etiology
-3 types of influenza virus: influenza A (most virulent, B, & C
-Influenza A and C infect multiple species, while B almost only infect humans
-Influenza A virus has 8 genes
-New and virulent flu strains are produced mainly from the effects of 2 surface proteins
-Hemagglutinin (H) - critical to virus entry into cell
-Neuraminidase (N) - allows virus to leave host cell after
-There are over 15 H’s and 9 dif. N’s in bird flu viruses
-Flu virus from birds - unable to replicate well in humans unless the move to an intermediate
host: chickens, geese, ducks
-flu genes of birds, pigs, humans can mix and produce new strains
Epidemiology
-occurs globally, year round
-serotypes that have been confirmed in humans (ordered by the # of known human pandemic
deaths):
-H1N1 - ‘Spanish Flu’
-H1N1 - ‘Asian Flu’
-H3N2 - ‘HK Flu’
-H5N1 - pandemic threat in 2007/8 flu season
-H7N7
-H1N2 - endemic in humans
-H9N2, H7N2, H7N3, H10N7
Modes of Transmission
-Respiratory Droplets - contain the virus and are expelled into the air by coughing, sneezing or
talking and enter the body thru a person’s mucous membranes (eg. nose, mouth)
-Direct Contact - the virus spreads from person-person from the hands of an infected person. A
person touches their mucous membranes with their contaminated hands
Lecture 10 - Influenza
1
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