avian and pandemic flu

8/12/2019 Avian and Pandemic Flu

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2/20

An acute respiratory illness resultingfrom infection with an influenza virus

Highly infectious and can spreadrapidly from person to person

Some strains cause more severeillness than others

What is influenza?


3/20

Types of influenza viruses

Influenza viruses are divided into threemain types: influenza A, , and !

A viruses " infect #irds and other

animals, as well as humans Aviruses " source of seasonal

influenza epidemics and all pandemics

Band Cviruses " infect humans onlyand do not cause pandemics


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$igratory

water #irds%omestic #irds

Where does influenza A virus

come from?

Humans

and other

animals

Human influenza A viruses start as avian ird' influenza viruses


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Influenza symptoms

Sudden onset

(ever, headache, muscle aches,

severe wea)ness *espiratory symptoms, e+g+, cough,

sore throat, difficulty #reathing


6/20

How influenza spreads

Spreads easily from person to personthrough coughing and sneezing

Transmitted #y:

" inhaling respiratory aerosols containing the virus,produced when infected person tal)s, coughs, or

sneezes

" touching an infected person or an item

contaminated with the virus and then touchingyour eyes, nose, or mouth


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!ourtesy of !%!


8/20

Seasonal influenza:

minor changes antigenic drift

-ccurs among influenza A virusesresulting in emergence of new variants

of prevailing strains every year .ew variants result in seasonal

influenza each winter

Some years are worse than others "partly related to degree of /drift0


9/20

What is an influenza pandemic?

Influenza pandemics are worldwideepidemics of a newly emergedstrain of influenza

(ew, if any, people have anyimmunity to the new virus

This allows the new virus to spread

widely, easily, and to cause moreserious illness


10/20

What causes a pandemic?

1andemics occur when a new

avian influenza strain ac2uiresthe a#ility infect people and tospread easily person to person

This can occur in two ways:

" *eassortment &an e3change ofseasonal and avian influenzagenes in a person or pig infectedwith #oth strains'

" $utation &an avian strain

#ecomes more transmissi#lethrough adaptive mutation of thevirus during human avianinfluenza infection'


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1andemic influenza:

ma4or changes antigenic shift

$a4or changes occur in the surface antigensof influenza A viruses #y mutation orreassortment

!hanges are more significant than thoseassociated with antigenic drift

!hanges lead to the emergence ofpotentially pandemic strains #y creating a

virus that is mar)edly different from recentlycirculating strains so that almost all peoplehave no pree3isting immunity


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Seasonal vs+ pandemic influenza 1andemic influenza is not 4ust a 5#ad flu,6 it is a wholly

new threat to humans A severe pandemic would cause social disruption unli)e

anything most persons now alive have ever e3perienced

!ompared to seasonal influenzas, pandemic influenzasinfect more people, cause more severe illness, andcause more deaths

Seasonal influenza viruses most often cause severedisease in the very young, the very old, and those withchronic illnesses, #ut pandemic influenza strains can

infect and )ill young, healthy people The highest mortality rate in the 787978 pandemic was

in people aged ;


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History of influenza


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1andemic influenza in the ;th!entury

78; 78; 789; ;;;

H7.7 H. H.

1918 Spanish Flu 1957 Asian Flu 1968 !n" #!n" Flu

;


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Why is there concern a#out an

influenza pandemic now?

A highly pathogenic avian influenza strain&A@H=.7' emerged in Hong ong in 788B,reemerged in #irds and humans in ;;, and isnow circulating widely in #irds in many countries

Since ;;, this strain has spread from #irds tohumans and as of August , ;;> has infected


16/20


17/20

Caccine

ecause the virus will #enew, there will #e novaccine ready to protectagainst pandemic influenza

at the start of a pandemic Specific vaccine cannot #e

made until the virus strainhas #een identified and willta)e at least months toproduce


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Antiviral drugs

Di)ely to #e the only ma4ormedical countermeasure

availa#le early in a pandemic

Encertainty a#out effectivenessfor treatment or prevention

E+S+ goal is to stoc)pile enough

antiviral drugs to treat =F of

the E+S+ population

*eproduced with permission from *oche 1roducts Dtd+ Tamiflu G


19/20


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-ther methods to reduce transmission

Hand hygiene &cleaning hands with soap andwater or an alcohol#ased hand ru#'

*espiratory hygiene, e+g+, 5!over your cough6

!leaning and disinfection of contaminated

o#4ects, surfaces 1hysical #arriers &e+g+, glass or plastic

5windows6 to protect front des) wor)ers'

Ese of personal protective e2uipment &11' insome settings &e+g+, healthcare' such asgowns, gloves, eye, and respiratory protection

avian and pandemic flu

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