Flu Flashcards
1918 flu virus
deadliest flu pandemic in history
killed 50 million people
proteins on the outer surface of the flu virus
hemagglutinin protein
neuraminidase protein
influenza is part of which family
orthomyoxiviridae
types of flu virus and which is essential to human disease
Types A, B and C
B is essential to human disease
flu genome
segmented, negative sense RNA
has an ability to reassort
the flu virus envelope contains
about 500 spikes
hemagglutinin and neuraminidase
influenza virus replication
endocytosis –> uncoating –> mRNA synthesis/RNA replication –> assembly –> exit
type of flu is based on
structure of internal proteins
Type A flu
infects humans, birds, pigs, horses, other animals
wild birds are the natural host
pandemics are associated with which type if influenza?
type A
type B influenza
usually found in humans
classified by strain only
type C influenza
human infections are rare
what are part of the influenza vaccine?
Hemagglutinin and Neuraminidase
hemagglutinin
surface of the virus
receptor for the virus to bind to the host cells
17 different subtypes
neuraminidase
surface of the virus
enzyme to let the new viral particles out of the host cell
10 different subtypes
classification of influenza strains
Type A,B,C/place isolated/number of isolate/year isolated
Influenza undergoes
antigenic changes in hemagglutinin and neuraminidase
influenza pandemics result from
antigenic shifts (antigen changing significantly)
symptoms of influenza
headache
fever
tiredness
aches
coughing
vomiting
runny/stuffy nose
sore throat
aches
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
rapid onset symptoms of the flu in adults
fever, coryza, headache, malaise, myalgia, sore throat, non-productive cough
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
