Intro to Respiratory Viruses Flashcards

1
Q

What are the different forms of upper respiratory infections (URI)?

A

rhinitis, pharyngitis, sinusitis and laryngitis

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2
Q

What are the different forms of lower respiratory infections (LRI)?

A

bronchitis, bronchiolitis, pneumonia

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3
Q

What is interstitial pneumonia?

A

infection involving alveolar septae and lining

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4
Q

what is pleuritis?

A

disease of pleura

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5
Q

What viruses cause the common cold?

A

rhinovirus (most common, URI, >100 serotypes, provoke asthma), Coronavirus (URI), Respiratory syncytial Virus (RSV, LRI, pneumonia= infants), Adenovirus (URI & LRI), Parainfluenza (URI but LRI if severe), cold symptoms= influenza, metapneumovirus (LRI), enterovirus (summer), EBV

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6
Q

What are the different kinds of Parainfluenza viruses and their associated illnesses?

A

HPIV-1 and 2: childhood croup, more in fall; HPIV 3: usually spring and early summer, HPIV 4: less common; all= childhood croup, laryngeal-tracheal infection, URI, LRI

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7
Q

What type of respiratory illness does HHV6 cause?

A

interstitial pneumonia, roseola (human herpes virus)

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8
Q

Which respiratory viruses are more common January-March?

A

RSV, Influenza, Para Influenza

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9
Q

Which respiratory viruses are more common July - September?

A

enterovirus, adenovirus, arbovirus

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10
Q

How are respiratory viruses spread?

A

contact w/ respiratory secretions or aerosolized micro droplets, self inoculation via hands in eyes (tear duct into nasopharynx), inhalation, fomites (i.e. tissues)

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11
Q

What are the three typical respiratory viral families?

A

Orthomyxovirus, paramyxovirus, adenovirus

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12
Q

What are the features of the paramyxoviral family?

A

characteristic finding if multinucleated cells in culture, RNA, envelop, easily sterilized/disinfected, Para influenza 1-4, mumps, morbillivirus (measles), pneumovirus (RSV and metapneumovirus)

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13
Q

What are some important clinical features of RSV?

A

most common respiratory virus in children and infants, extreme pathogenic effect on respiratory epithelium, recovery longer than bacterial

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14
Q

What are some important clinical features of metapneumovirus?

A

second most common virus in children, similar to RSV, detection largely limited to molecular approaches

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15
Q

What are some important features of adenovirus?

A

1-41 serotypes, aerosol enteric/respiratory, myocarditis in children (viremia), epidemic infections in close dense populations (military base), conjunctivitis or swimmer’s eye (pee in pool)

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16
Q

How is influenza acquired? What does it cause?

A

through respiratory tract; widespread disease including fever, myalgia, and headache

17
Q

What are the identifying features of orthomyxoviruses?

A

influenza; Hemagglutination protein (attach to cells, serotyping H Ag), Neurominidase protein (release of new viral particles from cells, RNA w/ 8 segments, facilitates rearrangement, serotyping N Ag

18
Q

What are the clinical features of orthomyxoviruses?

A

influenza A: pandemic and seasonal, birds, humans, pigs, LRI; influenza B: seasonal, humans and seals, LRI and GI; influenza C: mild illness, URI rarely LRI, limited outbreaks

19
Q

What are the replicative features of influenza?

A

(-) RNA, requires viral proteins w/ nuclear host proteins to produce mRNA and genome, in cytoplasm mRNA translated to produce viral proteins, assembly at plasma membrane, neurominidase required for bud separation from cell

20
Q

What is the importance of influenza H and N antigens?

A

used to serogroup influenza A (16H and 9N), Ab made to these, basis for flu vaccines, allows binding with host cell, H- fusion of viral envelope with endosome when acidified, N allows budding out from cell.

21
Q

What is antigenic drift?

A

RNA viruses make more mutations than DNA viruses, serogroups spread in population and have new mutations, gradually drift into new antigenic shape, now unrecognizable by immune system

22
Q

Why do we have seasonal epidemics of influenza?

A

antigenic drift, small changes in H and N, how it eludes immune system, why we vaccinate yearly and vaccine updated for predicted changes

23
Q

What impact does seasonal influenza have in US?

A

> 36K deaths (85% over 65) and 200K hospitalizations, 5-20% attack rate in gen pop and ~60% in nursing home, 10 bil. in lost productivity and medical cost

24
Q

What is antigenic shift?

A

wild birds have different type of influenza A than humans, pig infected with human and bird virus (in same cell), virus segments combine creating new serotype which infects people who lack immunity

25
Q

What caused H1N1 virus of 2009?

A

antigenic drift and shift

26
Q

What typically causes pandemic influenza A? What is the recipe for a pandemic?

A

antigenic shifted virus entering human population; novel virus (pop little or no immunity), capable of replication in humans, pathogenic and virulent in humans, and capable of human-human transmission

27
Q

Which viruses are being watched for the next pandemic? Why?

A

H5N1 and H7N9; rapid mutation, tendency to acquire genes from viruses infecting other animals, cause severe disease in birds and humans, birds that survive shed virus in feces for weeks, ~70% fatal in humans (minimal person to person spread, not well adapted yet)

28
Q

what are key features of bird influenza?

A

not commonly transmitted between humans, high morbidity and mortality for humans

29
Q

What were the notable influenza pandemics of the 20th century?

A

1918 Spanish flu (H1N1) ~20-40mil deaths (675K in US); Asian flu (H2N2) ~ 1-4 mil deaths (70K US); and Hong Kong Flu (H3N2) deaths 1-4 mil (34K US)

30
Q

why does influenza spread so quickly?

A

incubation: 2 days (1-4), viral shedding: begin 1 day before onset of symptoms, peak shedding first 3 days (correlates w/ fever), subsides by 5-7 days but up to 10+ in kids

31
Q

How can flu droplet spread be minimized?

A

limited study but: masks and respirators (N95), contact, droplet and droplet nuclei (airborne) can all occur, droplet most important (cover cough, sneeze, talk- increase coail distance, can be on surfaces)

32
Q

What determines vaccine for the year?

A

WHO makes recommendations based on surveillance data

33
Q

What is the site of action of antivirals for influenza?

A

amantadine and rimantadine proton transport into endosome preventing acidification; zanamivir and oseltamivir- neurominidase

34
Q

Flu Vaccine vs Antivirals?

A

V: best prevention, limited supply, 6-9mo to produce, manufacturing limited, efficacy dependent on prediction of strains (midseason shifts!); AViral: best at stopping spread, effective treatment/prophylaxis, valuable adjunct to vaccine, limited supply

35
Q

How do we treat colds?

A

can’t really test to find culprit (too many options takes too long to matter), fluids and rest (no AB unless evidence of B infection)