Respiratory viruses Flashcards by Emily Barker

The peak incidence of viral respiratory infection is in the _____

winter months

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Adenovirus infection is present ______ but cases occur periodically in _________

present throughout the year

outbreaks in institutional settings- ex military trainees

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The peak incidence of enterovirus respiratory disease is in the ______

late summer/ early fall

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

winter

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Parainfluenza virus and rhinovirus peak in the ______+

two peaks: one in fall, one in spring

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

immune responses

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

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

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

fever, malaise, muscle aches, cough, extreme fatigue

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

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

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How are respiratory viruses diagnosed?

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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What respiratory viruses have antivirals that can be used for treatment

influenza
RSV

ie distinguishing between rhinovirus and coronavirus is not clinically useful

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What causes symptoms of the common cold?

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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Describe the pathogenesis of LRT symptoms in viral infection

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

High systemic levels of IFN

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What is the pathology of SARSCoV?

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

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List recommended therapies for respiratory viral illness

hydration

chicken soup-antihistamine activity

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

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

amantadine and rimantadine

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What is the mechanism of action of oseltamivir and zanamivir?

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

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What drugs can be used for respiratory syncytial virus?

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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What is current thinking about transmission of respiratory viruses?

aerosols + many of these viruses

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

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What respiratory viruses can be prevented with a vaccine?

Study These Flashcards

influenza only

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

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

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

What two glycoproteins are present on the influenza virus envelope?

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hemagglutinin (H): critical for attachment and entry

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

Describe the general pattern of influenza epidemiology over time

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.

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

H protein

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

genetic reassortment

How does genetic reassortment happen for influenza virus?

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

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

antigenic shift

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 _________

antigenic drift

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

antigenic drift does not | completely change the H or N protein, some antibody protection is retained by the host

What is the source of novel H genes?

waterfowl

What is the role of pigs in influenza epidemiology?

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

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

Direct transmission of influenza from birds to humans NO human to human transmission, only affected people who directly handled birds

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

shift and drift

Describe the classic presentation of influenza

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

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

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

What bacteria most typically cause secondary pneumonia following influenza infection?

S pneumoniae, S aureus, H influenzae

How does co-infection with bacteria enhance viral infection?

Proteases secreted by bacteria enhance cleavage of hemagglutinin

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

adults over 65, people with COPD

Describe the progression of symptoms in RSV infection

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

What is the typical presentation of parainfluenza virus?

common cold with bronchitis fever rarely pneumonia, bronchiolitis CROUP

What types of infections can be caused by adenoviruses?

respiratory, GI, ocular depending on subtype

Where are the sites of latency for adenovirus?

adenoids, tonsils

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.

true!!

What are the major symptoms of adenovirus infection?

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

_____ are the most common respiratory viral pathogen

rhinovirus

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

URT

Rhinoviruses can exacerbate ______

asthma

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

winter and spring

Describe the clinical syndrome of SARS

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

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

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

Describe the presentation of WU virus

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

Respiratory viruses Flashcards

(53 cards)