Flu Flashcards by Olivia Hofer

1918 flu virus

deadliest flu pandemic in history
killed 50 million people

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proteins on the outer surface of the flu virus

hemagglutinin protein
neuraminidase protein

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influenza is part of which family

orthomyoxiviridae

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types of flu virus and which is essential to human disease

Types A, B and C
B is essential to human disease

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flu genome

segmented, negative sense RNA
has an ability to reassort

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the flu virus envelope contains

about 500 spikes
hemagglutinin and neuraminidase

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influenza virus replication

endocytosis –> uncoating –> mRNA synthesis/RNA replication –> assembly –> exit

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type of flu is based on

structure of internal proteins

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Type A flu

infects humans, birds, pigs, horses, other animals
wild birds are the natural host

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pandemics are associated with which type if influenza?

type A

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type B influenza

usually found in humans
classified by strain only

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type C influenza

human infections are rare

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what are part of the influenza vaccine?

Hemagglutinin and Neuraminidase

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hemagglutinin

surface of the virus
receptor for the virus to bind to the host cells
17 different subtypes

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neuraminidase

surface of the virus
enzyme to let the new viral particles out of the host cell
10 different subtypes

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classification of influenza strains

Type A,B,C/place isolated/number of isolate/year isolated

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Influenza undergoes

antigenic changes in hemagglutinin and neuraminidase

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influenza pandemics result from

antigenic shifts (antigen changing significantly)

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symptoms of influenza

headache
fever
tiredness
aches
coughing
vomiting
runny/stuffy nose
sore throat
aches

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do the cold and flu have the same symptoms?

NO!
fever is rare in the cold and prostration is never present in cold but is in the flu

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rapid onset symptoms of the flu in adults

fever, coryza, headache, malaise, myalgia, sore throat, non-productive cough

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when is the influenza virus contagious

AT ALL STAGES!!
(incubation, symptomatic, recovering)

mode of transmission of flu in humans

person to person
respiratory secretions (droplets)

incubation period of influenza

1-3 days

symptoms of influenza in children

higher fever, GI tract symptoms, otitis media, myositis, more frequent croup

who is at high risk for flu complications?

asthma heart disease elderly children/infants

Pneumonia and influenza are one of the

highest leading causes of death in the US

complications of influenza

primary viral pneumonia secondary bacterial pneumonia myositis cardiac involvement neurologic symptoms (rare)

pneumonia

fluid in air sacs of the lungs

symptoms of pneumonia

coughing up blood low blood pressure high heart rate

removal of sialic acids

enables bacterial attachment

due to co-pathogenesis there is a small increase in

viral infection due to bacterial infection becoming established

Guillain Barre syndrome and its relation to influenza

rare autoimmune disorder, damages nerves weakness/tingling sensations in both legs getting the vaccine/infection can trigger GBS

how is severity of flu season determined?

% of visits to outpatient clinics rates of influenza associated hospitalizations % of deaths resulting from pneumonia/influenza that occurred during each season

severity of flu seasons can be

different in children and adults

effectiveness of the seasonal flu vaccines sometimes have

not great numbers, but you should still get it (Sorry vaccine haters)

avian influenza

wild birds carry without illness --> can kill domestic birds humans can become infected

pandemic influenza involves

animals

Antigenic shift

by reassortment that involves a third species (mixing vessel)

swine flu

influenza type A - H1N1 can be passed to humans (by kissing pigs on the mouth LOL)

benefits of the flu vaccine

millions did not get the flu illness hundreds of thousands of hospitalizations are avoided thousands of deaths are avoided

influenza virus testing methods examples

Rapid influenza diagnostic tests RT-PCR Rapid cell culture

antiviral drugs for influenza

oseltamivir - Tamiflu (pill/liquid) Zanamivir - Relenza (inhalation) Peramivir - Rapivab (IV)

Drugs like tamiflu inhibit

neuraminidase protein so the virus cannot get released

Xofluza (baloxavir marboxil)

new antiviral flu inhibits polymerase acidic endonuclease (replication) single dose, first in class, oral

Coronavirus

can cause infections in animals/humans respiratory infections SARS, MERS, COVID-19

emergence of COVID-19

Wuhan, China caused by SARS-CoV-2 linked to large seafood and live animal market

symptoms of covid and flu

are different (ex: shortness of breath in covid, not in flu)

when looking at covid and flu symptoms, there are

differences on a clinical symptom basis

duration of symptoms (covid and flu)

covid - 1-2 weeks, or 6 weeks flu - 3-7 days

incubation time (covid and flu)

covid - 2-14 days flu - 1-4 days

median hospital stay and fatality rate (covid and flu)

covid - 12 days, 2.9% flu - 4 days, 0.1%

SARS-CoV-2 and Influenza A/B Test

Roche received FDA Emergency Use Authorization multiplex RT-PCR assay detection and differentiation of SARS-Cov2, Influenza A and B