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Respiratory Viruses > Respiratory Viruses > Flashcards

Respiratory Viruses Flashcards

1
Q

Respiratory Infections cause what percentage of acute illnesses??

A

80% = resulting in a loss of time from work

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2
Q

What percentage of resp infections are viral?

A

80%

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3
Q

What do infections of the upper resp tract result in?

A

short absences, influenza longer absences and pneumonia (often due to secondary bacterial infection) longer still

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4
Q

what do resp infections feature?

A
  • seasonality
  • short incubation periods (1-4days)
    HIGHLY CONTAGIOUS
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5
Q

Most common resp viruses?

A

RSV, adenovirus, rhinovirus, bocavirus

- during outbreaks the outbreak virus becmes predominant, particularly influenza

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6
Q

influenza

A

we are extremely susceptible to respiratory infections - worst for causing lower resp infections = influenza
- these viruses are members of the orthomyxovirus group

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7
Q

characteristics of influenza viruses

A
  • enveloped, stranded RNA viruses

classified into 3 serotypes: a , b & c

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8
Q

A, B & C serotypes of influenza? (basics)

A

A - naturally found in the gut of waterfowl but can infect poultry, swine, horses & humans
B & C - infect only humans and have never caused pandemics

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9
Q

natural reservoir of influenza?

A

most come from birds (gut of wild birds) - including H1N1, but H5 & H7 are the only ones that will show in birds

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10
Q

Influenza causes what?

A

viral penumonia of varying severity which is associated with fever, myalgia and dry cough

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11
Q

when do people see improvement in symptoms from influenza?

A

usually within 2-5 days

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12
Q

Influenza A

A

causes the most severe disease and is associated with epidemics and pandemics

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13
Q

what does the surface of influenza A look like?

A

studded with spikes composed of two different glycoproteins:
hemagglutin (15 serotypes, mediated viral attachment to the host cell
neuraminidase (thought to mediate viral fusion to and budding from the host cell

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14
Q

How are influenza A serotypes named?

A
  • serologic types of these glycoproteins are given numbers (1,2,3..) The viruses are designated by the major serotype, the place of initial isolation, the isolate number, the year of detection and the hemagglutin neuraminidase types
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15
Q

An example of an Influenza A serotype?

A

A (A/B/C) / Bangkok (place) / 1 (isolet #) / 79 (year) / H3N2 (hemo/neuro types)

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16
Q

what is Antigenic Drift?

A

antigenic variation that can result from minor mutations - which result in frequent small changes in the circulating viral types
(year to year = hardly any different ,. but 10 years = big difference from where you started)

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17
Q

what is Antigenic Shift?

A

Major antigenic variation results when there is recombination of hemagglutin and neuraminidase serotypes, presumably from coinfection of two viral types in the same host cell -
2 viruses infect 1 cell = genes mix and produce a different HA/NA type, this is when you get a pandemic!

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18
Q

what does an antigenic shift cause?

A

it occurs suddenly and unpredictably and can result in the emergence of a new viral strain to which there is essentially no immunity in the population
highly contagious nature = pandemic can result

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19
Q

who usually has the highest mortality due to pandemics?

A

elderly and persons of all ages with cardiorespiratory diseases

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20
Q

which pandemics were exceptions?

A

pandemics of 1889-90, 1917-18 and 2009 = they were associated with higher mortality in the young and healthy

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21
Q

Where do the first strains arise?

A

due to their practices= arise there first in the spring, we get it in the fall so we can prepare for it

  • in North America they can manufacture vaccines - which can effectively prevent widespread mortality
  • these vaccines are prepared from virus grown in eggs and are inactivated whole virus or “split virus”, composed mainly of hemagglutin antigens
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22
Q

What is a pandemic?

A
  • occurs anywhere, RANDOM

- pandemic strains USUALLY replaces previously circulating strains

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23
Q

Human Flu

A
  • fever, chills, cough, myalgia, 3-5 days
  • usually a minor illness in young and healthy
  • often fatal in elderly/cardiorespiratory patients
  • the flu is NOT vomiting and diarrhea (but 25% of kids have that when they have the flu)
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24
Q

Spanish Flu

A

(the second wave was worse than the first)
- only influenza associated with encephalitis lethargica (Hitler has this) which causes symptoms of Parkinsons disease (dopamine deficiency) and personality changes - you become very persuasive

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25
Q

Swine

A
  • unlikely to mutate into virulent strain
  • very mild illness
  • mainly infecting young persons
  • higher mortality in pregnant
  • replaced previous strains
26
Q

2009 H1N1

A
  • CD8 tcell responses limit severity
  • similar to past H1N1
  • people born before 1957 - had cross reacting Antibodies which helped prevent infection
  • mortality associated with high levels of interleukin 17
27
Q

How can Influenza A & B be treated?

A

in chronic care facilities interrupted by administering zanamivir or oseltamivir

28
Q

Parainfluenza Viruses

A
  • paramyxoviruses (ss RNA) and are related to mumps

- have hemagglutin and neuraminidase

29
Q

how many serotypes of Parainfluenza Viruses?

A
  • 4 serotypes: producing different clinical syndromes
30
Q

Parainfluenza 1&3 ?

A

1 & 3: closely related and cause acute larngotracheitis (croup - can accurately diagnose over the phone - awful cough), brochiolitis and pneumonia mainly in young children

31
Q

Parainfluenza 2

A

causes severe lower respiratory tract disease in young children

32
Q

Parainfluenza 4

A

causes a milder respiratory illness in all age groups

33
Q

treatment?

A

no treatment, but mild croup responds to inhalation of cold moist air
- corticosteroids/nebulized epinephrine

34
Q

Respiratory Synctial Virus

A
  • also paramyxovirus, named for its ability to produce cell fusion in tissue cultures
35
Q

What does RSV cause?

A

MOST IMPORTANT cause of respiratory disease in infants

36
Q

Symptoms of RSV?

A

usually begin with rhinitis which progresses to bronchiolitis and necrotizing pneumonia
- cough and wheezing which may be severe, leading to hyperinflation, atelectasis and hypoxia

37
Q

Mortality due to RSV?

A

0.5-1% and younger children are more severly affected

in infants with congenital heart disease or immunocompromised - mortality may exceed 15%

38
Q

Pathogenesis for RSV?

A

incompletely understood but there appear to be immunologic factors

39
Q

When do community outbreaks occur?

A

annually in the colder weather and affect about 50% of families
^ adults can get a flu-like illness

40
Q

Tests available for RSV?

A

rapid test for viral antigen in respiratory secretions

treatment - provide O2 and mechanical ventilation as necessary and aerosolized ribavirin

41
Q

Adenovirus

A
  • causes EVERYTHING - there is very little that it cannot cause
  • naked (nonenveloped - aka easy to transmit)
  • ds DNA viruses which replicate in the nuclei of host cells and are released by host cell destruction (LOTS of inflammation)
42
Q

What does the inflammation from adenoviruses cause?

A

produces epithelial cell necrosis which can cause a diversity of symptomatology

43
Q

how many adenovirus serotypes?

A
  • 47

- known to infect humans (mainly small children and military recruits)

44
Q

What percentage of adenovirus infections associated with disease?

A

45%

45
Q

what percentage of acute febrile illness are in children?

A

10% - under two is attributed to adenovirus

46
Q

What are adenoviruses capable of?

A

latency by integration (can hide out in our genomes) of viral DNA into the host genome

47
Q

Can adenoviruses spread?

A

they spread by either respiratory or fecal-oral routes

48
Q

Rhinovirus

A
  • inflammation of lining of the nose
  • naked pircornaviruses - distinguished from the enteroviruses by their acid lability and an optimum temperature of 33 degrees for replication
49
Q

how many serotypes of Rhinovirus?

A

108 - theyre the main viruses associated with the common cold syndrome

50
Q

What does the large # of serotypes ensure?

A

that people remain susceptible to infection throughout life

51
Q

How is rhinovirus transmitted?

A

mainly by contact

52
Q

what are acute symptoms of rhinitis?

A

nasal obstruction and sore throat - thought to result from a combination of mucosal cell damage and soluble mediators of inflammation - especially bradykinin

53
Q

when do the acute symptoms clear? (rhinitis)

A

usually by seven days

cold usually only lasts 7 days and is cleared by 10

54
Q

what is it if a cold lasts longer than 10 days? (rhinitis)

A

likely bacterial sinusitis

55
Q

Symptomatic relief? (rhinitis)

A
  • ibuprofen, decongestants and antihistamines are helpful in older children and asults
    nasal aspirator for infants
    steam inhalation, bed rest, Vit C and echinacea remain unproven
56
Q

What else may reduce symtpoms? (rhinitis)

A

zinc gluconate lozenges and ginseng supplements may reduce rhinitis symptoms and shorten the duration

57
Q

Bocavirus

A
  • name dervies from bovine and canine

- bocavirus is a parvovirus which is extremely common in respiratory samples

58
Q

What does it cause?

A

bocavirus is a probably cause of resp symptoms and has been linked to GI symptoms

59
Q

how many types of bocavirus?

A

4 types, 1, 2, 3, & 4

60
Q

Coronavirus

A

single stranded RNA viruses associated with the common cold syndrome and are stains with SARS

61
Q

PBI - F2 protein

A
  • bings to inner mitochondrial membrane
  • sensitized cells to apoptotic stimuli
  • inflammatory
  • may down regulate immune response
  • significant virulence factors
62
Q

Influenza Prevention & Treatment

A
  • vaccines are inactivated whole virus or “split virus” composed mainly of hemmaglutinin
  • rapid tests for viral antigen in nasal secretion are widely available (tell you if its A or B)
  • Influenza A & B can be treated and outbreaks in chronic care facilities interrupted by administering zanamivir and or oseltamivir
  • antiviral drugs for everyone

Respiratory Viruses (1 decks)

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