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Miguel > Respiratory Viruses > Flashcards

Respiratory Viruses Flashcards

1
Q

Lower respiratory infections were the _____ global cause of deaths in 2016

A

4th

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2
Q

Lower respiratory infections were the _____ global cause of deaths in low income countries in 2016

A

1st

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3
Q

Leading infectious disease deaths in 2019

A

Lower Respiratory Infections
Diarrhoea
HIV/AIDS
Malaria

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4
Q

Leading causes of death in children <5 years old, 2019

A

Lower Respiratory Tract Infectious
Neonatal preterm birth
Neonatal asphyxia & trauma
Diarrheal diseases
Congenital birth defects

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5
Q

Leading causes of death in children
<5 years old - 1990 vs 2019

A

LRTI, diarrheal diseases, neonatal preterm death, measles all greatly decreased
Scientific breakthroughs have diminished affects of infectious diseases

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6
Q

Principle viral aetiological agents of LRI

A

Influenza A,B, (C)
RSV A & B
Human metapneumovirus (hMPV)
Human parainfluenza virus types 1-3
Adenovirus
Picornavirus
Coronavirus
Bocavirus

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7
Q

Characteristics of Viral Respiratory Infections of Known Aetiology

A

Coryza
Sore throat
Headache
Cough
Activity restriction
Lower respiratory symptoms
(NOT SPECIFIC)

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8
Q

What family do Influenza A, B, C, D, Thogovirus and Isavirus belong to

A

Orthomyxoviridae

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9
Q

What are the usual epidemic strains of influenza?

A

H1N1
H3N2

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10
Q

What percentage of the US population get the flu and how many are hospitalised?

A

3-11%
380,000

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11
Q

High risk groups for influenza

A

People ≥ 65
Nursing home residents
Children 6-23 months
Chronic heart or lung diseases
Immunodeficiencies

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12
Q

Influenza symptoms

A

fever (usually high)
headache
extreme tiredness
dry cough
sore throat
runny or stuffy nose
muscle aches (myalgia)
Stomach symptoms, such as nausea, vomiting, and diarrhea, children>adults

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13
Q

Influenza complications (3)

A

Primary viral pneumonia
Pneumonia dehydration
Worsening of chronic medical conditions (eg congestive heart failure, asthma, diabetes)

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14
Q

Transmission of influenza

A

person to person - respiratory droplets from coughing and sneezing
touching infected surfaces and then mouth or nose

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15
Q

When is influenza infectious

A

1 day before - 5 days after symptoms

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16
Q

Incubation period of influenza

A

24 hours to 4-6 days

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17
Q

Disease duration of influenza

A

7-14 days
Up to 3 weeks

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18
Q

Reservoir of influenza A viruses

A

Ducks?
Don’t kiss pigs
Fowl, horse, whales, seals (birds -> mammals -> humans?)

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19
Q

What responses are induced following infection and which cells?

A

T cell response
CD4+
CD8+

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20
Q

What is T cell role in protection against influenza?

A

High CD8+ T cells
Good protection against re-infection with same strain - life long immunity
Little resistance to 2nd infections with new variants - virus can mutate

21
Q

Mechanisms of influenza disease(2)

A

Systemic
Local

22
Q

_______ is essential for virus infectivity

A

haemagglutinin cleavage

23
Q

Influenza differential pathology due in part to_______

A

Haemagglutinin cleavage site

24
Q

Timeline of human flu pandemics

A

1918 - Spanish flu (H1N1) 20-50 million dead
1957 - Asian flu (H2N2)
1968 - Hong Kong flu (H3N2)
1977 - Russian flu (H1N1)
1997 - first Avian flu
2009 - Swine flu (H1N1)

25
Q

Antigenic Drift

A

Genetic mutations
HA gene changes -> antigen it encodes changes shape -> antibodies that normally bind to it no longer can
RNA polymerase = error prone :(
Exposed to new strains - virus more fit to replicate
=> endemic

26
Q

Antigenic shift

A

Genetic change - reassortment +/- genetic mutations - that enables flu strain to jump from one animal specifies to another

=> Pandemic

27
Q

3 ways antigenic shift can occur

A

1) Aquatic bird passes strain to intermediate host, human passes strain of same virus to pig. Genes from both strains mix and form new strain which can spread from intermediate host (like shuffling a deck of card). Genome segments mix

2) Bird strain can jump directly to human without undergoing genetic change

3) Bird strain can jump directly to intermediate host to human without undergoing genetic change

28
Q

Avian Flu

A

1997 - avian influenza passed directly from birds to humans
Hong Kong 1997 variant - avian H5N1 virus - infected 18 people, killed 6 (high mortality rate) ~ 30%
Virus was poorly transmissible between humans

29
Q

Clinical features of confirmed human cases of avian influenza A (H5N1)

A

Fever
Cough
Pulmonary infiltrates
Exposure to ill poultry
Shortness of breath
Diarrhoea
Headache
Myalgia

30
Q

Influenza pandemic preparedness

A

Sentinel diagnostic labs worldwide
Anti-viral stockpiling - Oseltamivir, Zanamivir (limited supplies)
Vaccine stockpiling - Only 8 countries with manufacturing facilities

31
Q

Swine Flu Pandemic 2009 - strain

A

A/H1N1

32
Q

Swine Flu Pandemic 2009 - transmission

A

Unusual cocktail of avian, swine and human viruses
Pigs harbour several flu viruses, they act to form new strain. Transmission via inhaling viral particles

33
Q

Swine Flu Pandemic 2009 - symptoms

A

High fever
Cough
Breathing difficulties
Loss of appetite

34
Q

Pandemic

A

2 or more WHO regions affected
(Spread not severity is decisional criterion)

Government must respond

35
Q

Swine Flu Pandemic 2009 - High risk groups
(5 chronic diseases + 5 others)

A

chronic lung, heart, kidney, liver, neurological disease

immunosuppression
diabetes mellitus
patients who have had drug treatment for past three years
pregnant women
people aged 65 and older

36
Q

Epidemic vs pandemic

A

Epidemic - disease that affects a large number of people within a community, population, or region
Pandemic - disease that’s spread over multiple countries or continents

37
Q

What sort of epidemic is influenza?

A

Seasonal

38
Q

Immune Response to Influenza

A

Virus attacks cilia in LRT
Innate response
Interferon response
Virus eliminated 6-10 days
Antibody response
Antibodies prepare body for re infection of same strain

39
Q

Systemic Infection

A

Can affect many organs
Enzyme found on all cells
High pathology

40
Q

Local infection

A

Affects local organs e.g respiratory and GI in birds
Enzyme only in cells of the lungs and GI tract
Low pathology

41
Q

HA cleavage site cleaved by _______ from HA0 to one of HA1-HA11

A

Cellular protease

42
Q

Influenza virus morphology

A

Envelope virus - derived from infected cell membrane
Surface glycoproteins - Neurominidase (tetramer), HA (homotrimer)
Negative strand RNA
M2 protein - forms pore between cell membrane and viral envelope
8 genomic segments - replication and survival
Matrix protein - gives morphology/shape
RNA dependent RNA polymerase complex made up of PB1, PB2 and PA

HA is surface cell receptor; 18 types
NA cleaves terminal sal acid; 11 types

Influenza is endocytosed -> reduces pH -> change in HA -> movement to juxtaposition of endosomal membrane -> Viral envelope able to fuse with cell membrane - M2

43
Q

Pattern of infection

A

No prior antibodies = surge = pandemic
People build resistance but virus may mutate
Epidemics occur
Pandemic again

44
Q

Interpandemic period

A

Time between 2 pandemics

45
Q

Define endemic

A

Infection is constantly present or maintained at baseline

46
Q

Incubation period

A

Period between infection and display of symptoms, in which the virus is replicating.

47
Q

Effect of Covid-19 lockdown on other respiratory viruses

A

Implementation of masks, social distancing and lockdown led to a dramatic decrease n cases of influenza.

48
Q

Define epidemic threshold

A

Indicates the level of incidence above which a disease requires an urgent response.

49
Q

Reye’s syndrome

A

Reye’s syndrome, a complication of influenza in children <16 years, however its neurological and thought to be associated with high-dose aspirin

Miguel (8 decks)

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