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Lecture 10

HLTA01 Lecture 10 Notes.docx


Department
Health Studies
Course Code
HLTB21H3
Professor
Caroline Barakat
Lecture
10

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HLTA01 Lecture 10
Origins of the influenza disease is unknown
Been reported by Hippocrates recorded the pandemic in the year 412 BC
Since 1580, there have been 31 additional flu pandemic recorded
Spanish Flu (1918-1919)
o Named like this because there was no censorship about the epidemic of Spain
o Approximately 50M deaths worldwide in less than 2 years
o Many deaths in US mostly in NY City
o Sudden, impacted the younger population compared to older population
o The entry of the disease was the nasal pathway and in some countries people were fined if
they didn’t wear the mask
o H1N1 strain
Symptoms
o Fever, chills, headache, weakness and fatigue as well as coughing, sneezing, runny nose
(coryza)
o Residual cough and tiredness lasts up to 6 weeks
o Complication can include ear infections, pneumonia, dehydration and death
Ethiology
o 3 types of influenza virus: Influenza virus A (more virulent), B and X
o Influenza A and C infect multiple species while B almost exclusively infects humans
o A has 8 genes
o New and virulent flu strains are produced mainly from the effects of two surface proteins
1. Hemagglutinin (H) critical to virus entry into cell
2. Neuraminidase (N) allows virus to leave host cell after replication and move from cell to
cell
o There are 15 H’s and 9 different N’s in bird flu viruses
o Flu virus from birds unable to replicate well in humans unless they move to an intermediate
host: chickens, geese, ducks, pigs when mutation occurs in this it’ll replicate REALLY well in
humans
o The birds carry it in their intestines and spread it by flying everywhere
o The virus spreads by the feces dropped in the water
o Flu genes of birds, pigs, humans, can mix and produces new strains
o Avian flu = originates from chickens
Antigenic drift: random mutations that change the genes causing the virus to change; can cause a
pandemic
Epidemiology
Occurs globaly, year round
Serotypes that have been confirmed in humans (ordered by the number of known human pandemic
deaths):
o H1N1 Spanish Flu
o H2N2 Asian Flue
o H3N2 Hong Kong Flu
o H5N1 pandemic threat in 2007 8 flu season slaughtered a lot of chickens
o H7N7
o H1N2 endemic in humans and pigs
o H9N2, H7N2, H7N2, H10N7
Mode of Transmission:
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