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FM3_ EB > Respiratory viruses > Flashcards

Respiratory viruses Flashcards

1
Q

The peak incidence of viral respiratory infection is in the _____

A

winter months

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2
Q

Adenovirus infection is present ______ but cases occur periodically in _________

A

present throughout the year

outbreaks in institutional settings- ex military trainees

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3
Q

The peak incidence of enterovirus respiratory disease is in the ______

A

late summer/ early fall

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4
Q

Coronavirus, influenza virus, and SRV all peak in the _____

A

winter

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5
Q

Parainfluenza virus and rhinovirus peak in the ______+

A

two peaks: one in fall, one in spring

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6
Q

Respiratory viruses are generally poor at generating_____ so re-infections are common

A

immune responses

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7
Q

Least the 10 viruses that cause respiratory illness that were covered in this class

A 
Influenza A, B, C
Enterovirus
Adenovirus
Parainfluenza virus
Respiratory syncytial virus
Rhinovirus
Coronavirus
Metapneumovirus
Human bocavirus
WU virus
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8
Q

Many respiratory viruses cause similar syndromes. List some symptoms that are somewhat specific for influenza

A

fever, malaise, muscle aches, cough, extreme fatigue

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9
Q

RSV causes serious ____ respiratory tract infections in ____ (age)

A

lower respiratory tract infections
infants 6 mo- 1 year
hospitalization is more common in boys

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10
Q

How are respiratory viruses diagnosed?

A

Culture from throat swabs, detected by immunofluorescent within 24-48 hours.
Cytopathic effects take longer to detect and may or may not be distinctive
PCR tests are available

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11
Q

What respiratory viruses have antivirals that can be used for treatment

A

influenza
RSV

ie distinguishing between rhinovirus and coronavirus is not clinically useful

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12
Q

What causes symptoms of the common cold?

A

replication of virus in the epithelial lining of the URT
irritation of nerve endings–> cough
histamines/ bradykinin–> mucus, congestion
viral replication results in killing of epithelial cells in some cases, ciliary action is often paralyzed

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13
Q

Describe the pathogenesis of LRT symptoms in viral infection

A

sloughing of dead cells blocks airways and results in dyspnea (more severe in infants)
chemotactic factors for eosinophils can exacerbate asthma/ COPD
fever from IL-1 or IFN

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14
Q

What is the cause of the muscle aches and malaise seen in influenza infection?

A

High systemic levels of IFN

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15
Q

What is the pathology of SARSCoV?

A

diffuse alveolar damage, desquamation, hyaline membranes, alveolar edema,
inflammation, syncytia formation, and thickened alveolar walls

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16
Q

List recommended therapies for respiratory viral illness

A

hydration

chicken soup-antihistamine activity

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17
Q

Describe how to help counsel patients about appropriate use of OTC agents for respiratory viral illness

A

OTCs: antihistamines, decongestants, expectorants, cough suppressants, pain relievers
recommend patients purchase drugs specific to their symptoms rather than formulated combinations (ex don’t take decongestants for influenza)

never use aspirin in kids- Reye’s syndrome

zinc- may inhibit rhinovirus proteases

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18
Q

What two drugs previously used to treat influenza are no longer prescribed due to high rates of resistance?

A

amantadine and rimantadine

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19
Q

What is the mechanism of action of oseltamivir and zanamivir?

A

neuraminidase inhibitors- block release of virus from cells, must initiate within 48 hours

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20
Q

What drugs can be used for respiratory syncytial virus?

A

aerosolized ribavirin in hospitalized infants
debate about efficacy

Palivizumab is a monoclonal antibody against RSV fusion protein, used for prevention and therapy in severe cases

** breastfeeding is protective- mom secretes anti-RSV antibodies

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21
Q

What is current thinking about transmission of respiratory viruses?

A

aerosols + many of these viruses

can survive for days on surfaces contaminated by “wet secretions”

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22
Q

What respiratory viruses can be prevented with a vaccine?

A

influenza only

failed attempts to make RSV vaccine
rhinovirus-100s of serotypes

23
Q

What is the difference between the traditional influenza vaccine and FluMist?

A

traditional: killed vacine
FluMist: live attenuated virus, so not for use in children, elderly, pregnant, or immunocompromised

24
Q

What two glycoproteins are present on the influenza virus envelope?

A
  • hemagglutinin (H): critical for attachment and entry

- neuraminidase (N): important for viral release from cells

25
Q

Describe the general pattern of influenza epidemiology over time

A

The pattern begins with a
pandemic. In the inter-pandemic period we see epidemics that tend to decrease in severity
followed by the outbreak of another pandemic where a large number of people are infected.

The epidemics gradually decrease in severity because the percentage of the population with antibodies against the H protein increases and thus fewer people are susceptible.

26
Q

Influenza viruses that cause pandemics have been found to encode a new subtype of ____ that people have never seen before and are therefore not protected

A

H protein

27
Q

_________ has been found to be the key factor in the ability of influenza to cause pandemics

A

genetic reassortment

28
Q

How does genetic reassortment happen for influenza virus?

A

Reassortment happens when two different influenza viruses infect the same host cell. Because the genome of the virus is segmented, the newly made genome segments can be randomly packaged into
virus particles generating a reassortant virus with a new H protein

29
Q

The event resulting in the generation of an influenza virus with a new H protein is known as _________

A

antigenic shift

30
Q

The acquisition of point mutations in H and N proteins of influenza that increase the resistance of the virus to the host immune response is _________

A

antigenic drift

31
Q

Why are viruses less able to cause severe disease after antigenic drift (vs antigenic shift)

A

antigenic drift does not

completely change the H or N protein, some antibody protection is retained by the host

32
Q

What is the source of novel H genes?

A

waterfowl

33
Q

What is the role of pigs in influenza epidemiology?

A

pigs are susceptible to infection with both human and avian strains of influenza
virus- if they are co-infected with multiple strains, they serve as mixing vessels for generation of reassorted viruses

34
Q

What was significant about the 1998 outbreak of influenza in Hong Kong?

A

Direct transmission of influenza from birds to humans

NO human to human transmission, only affected people who directly handled birds

35
Q

Since influenza can undergo _____ and ____, the protection provided by immunization is short lived and a new vaccine is needed every year

A

shift and drift

36
Q

Describe the classic presentation of influenza

A

fever, headache, myalgia, fatigue, dry cough, sore throat, nasal congestion

not common: rhinorrhea, GI symptoms

systemic symptoms for 3-5 days, respiratory symptoms for an additional 4 days

37
Q

What groups are at greatest risk of developing viral pneumonia from influenza?

A

young children, elderly, pregnant women, chronic lung or CV disease

38
Q

What bacteria most typically cause secondary pneumonia following influenza infection?

A

S pneumoniae, S aureus, H influenzae

39
Q

How does co-infection with bacteria enhance viral infection?

A

Proteases secreted by bacteria enhance cleavage of hemagglutinin

40
Q

RSV most classically causes disease in young children but is increasingly significant in :

A

adults over 65, people with COPD

41
Q

Describe the progression of symptoms in RSV infection

A

Starts with nasal congestion, pharyngitis, fever
followed by dyspnea, wheezing

Chest X ray shows interstitial infiltrates and hyperinflation of the lungs

can cause otitis media, sinusitis, can lead to secondary bacterial infections

42
Q

What is the typical presentation of parainfluenza virus?

A

common cold with bronchitis
fever

rarely pneumonia, bronchiolitis

CROUP

43
Q

What types of infections can be caused by adenoviruses?

A

respiratory, GI, ocular depending on subtype

44
Q

Where are the sites of latency for adenovirus?

A

adenoids, tonsils

45
Q

True or false: Even though the respiratory types of adenovirus don’t cause GI symptoms, they can be shed in the stool so in addition to spread via wet secretions, oral-fecal transmission may be possible.

A

true!!

46
Q

What are the major symptoms of adenovirus infection?

A

infants: cough, pharyngitis
children: pharyngitis, tracheitis
teens: severe acute respiratory disease wiht cough, fever, sore throat, runny nose
adults: cold

immunocompromised: pneumonia, cystitis, CNS infection

some subtypes: ocular–> keratoconjunctivitis; hemorrhagic cystitis

47
Q

_____ are the most common respiratory viral pathogen

A

rhinovirus

48
Q

Rhinoviruses remain primarily in the ______ and are not associated with croup, pneumonia, bronchiolitis

A

URT

49
Q

Rhinoviruses can exacerbate ______

A

asthma

50
Q

Coronaviruses cause common colds and are most common in ____ and ____

A

winter and spring

51
Q

Describe the clinical syndrome of SARS

A

novel coronavirus that jumped from wild cats or bats to humans in China

2-7 days of mild URT “cold” that progresses to fever, rigors, cough, dyspnea, malaise, headache, hypoxia, occasionally diarrhea

often need respiratory support

52
Q

______ can cause respiratory syndromes. Peak incidence is in the summer so they are referred to as “undifferentiated febrile illness” or “summer grippe”

A

enteroviruses

present with cough, sore throat, fever, rarely LRT symptoms like bronchitis
complication- acute myocarditis exacerbated by exercise

53
Q

Describe the presentation of WU virus

A

recently discovered
high hospitalization rate in children
bronchiolitis, croup, pneumonia

FM3_ EB (25 decks)

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