SM_179a: Viral Infections Flashcards
Which viruses infect the respiratory tract?
- Influenza virus
- Respiratory syncytial virus
- Human metapneumovirus
- Parainfluenza virus
- Rhinovirus
- Coronavirus
- Adenovirus
- Bocavirus
(other viruses utilize but do not infect the respiratory tract)
List the respiratory viruses and their family and genetic material
- Influenza virus: orthomyxoviridae, (-)ssRNA, segmented
- RSV: respiroviridae, (-)ssRNA
- Metapneumovirus: respiroviridae, (-)ssRNA
- Parainfluenza virus: paramyxoviridae, (-)ssRNA
- Rhinovirusa: picornaviridae, (+)ssRNA
- Coronavirus: coronaviridae, (+/-)ssRNA
- Adenovirus: adenoviridae, dsDNA
- Bocavirus: parvoviridae, (+/-)ssDNA
Pharyngitis is most commonly caused by ______
Pharynigitis is most commonly caused by adenovirus
Croup is most often caused by ____ and _____
Croup is most often caused by PIV1 and PIV2
Bronchiolitis is most commonly caused by ___
Bronchiolitis is most commonly caused by RSV
Pneumonia in adults is most commonly caused by ______
Pneumonia in adults is most commonly caused by influenza
_____ cause the common cold
Multiple viral pathogens cause the common cold
(rhinitis, nasal congestion, sneezing, pharyngitis, cough, hoarseness)
A respiratory virus is usually the cause of pharyngitis when there is associated _____
A respiratory virus is usually the cause of pharyngitis when there is associated nasal congestion
Croup is caused most often by ____ and symptoms arise from _____
Croup is caused most often by PIV1 and PIV2 and symptoms arise from inflammation and obstruction of the subglottic structures
Tracheobronchitis is characterized by a ______ and is caused by _____ and _____
Tracheobronchitis is characterized by a non-productive cough and is caused by influenza and PIV
Bronchiolitis is _____ characterized by _____ and is most commonly caused by _____
Bronchiolitis is viral infection of the terminal bronchiolar epithelial cells characteried by wheezing and nasal flaring and is most commonly caused by RSV
- Edema and excessive mucus results in obstruction of small airways
- Shortness of breath, increased work of breathing
Describe the classification of influenza
Influenza
- A: humans, mammals, and birds - acquatic birds are main reservoir
- B: severe disease in elderly and at risk, no pandemics
- C: disease in children, most adults have protective immunity
Influenza A is characterized by _____ and _____
Influenza A is characterized by hemagglutinin and neuraminidase
- Hemagglutinin (16 types): binds sialic acid, limits species transfer
- Neuraminidase (9 types): viral release and propagation
Antigenic drift in influenza is ____ and is associated with _____
Antigenic drift in influenza is minor change based on mutations in genome RNA secondary to poor fidelity of RNA polymerase and is associated with epidemics
Antigenic shift in influenza is _____ and is associated with _____
Antigenic shift in influenza is a major change based on reassortment of segments of genome RNA and is associated with pandemics
H1N1 was a ______ reassortment
H1N1 was a quadruple reassortment
(Asian and European influenza, avian influenza, human influenza)
Describe the transmission of influenza
Influenza
- Invades ciliated epitheial cells of upper respiratory tract
- Spread via respiratory droplets and fomites
- Droplets are large, travel short distances, and are viable for up to 24 hours on surfaces
- Shed for 1-2 days prior to symptoms and up to 5 days after symptom onset
Common symptoms of influenza include _____, _____, _____, and _____
Common symptoms of influenza include fever, mylagias, sore throat, and non-productive cough
- All symptoms not seen in all patients
- Fever of abrupt onset
- Severe cases present as pneumonia
Main complications of influenza are _____ and _____
Main complications of influenza are secondary bacterial pneumonia (Staph aureus and Strep pneumoniae) and exacerbation of cardiopulmonary conditions
(mortality rates higher in older age)
_____ is the preferred testing method for influenza
PCR identification is the preferred testing method for influenza
- Clinical syndrome and rapid antigen detection can also be used
___ are NOT effective for treatment of influenza
M2 inhibitors (amantidine, rimantidine) are NOT effective for treatment of influenza
_____ used to treat influenza prevent virus release from the cell and have the effect of _____
Neuraminidase inhibitors (oseltamivir, zanamivir) used to treat influenza prevent virus release from the cell and have the effect of reducing symptoms by 24 hours and transmission by 24-48 hours
_____ used to treat influenza act by ____
Cap-dependent endonuclease inhibitors (Biloxivir) used to treat influenza act by stopping mRNA synthesis
- About as effective as oseltamivir
- One-time dose
Which factor placed her at risk for severe respiratory distress from influenza infection?
Pregnancy
Who should be treated for influenza?
- Start within 48 hours of symptoms
- Severe symptoms or anyone hospitalized
- Higher risk for complications
- < 19 years of age and receiving long-term aspirin therapy
- Immunosuppressive conditions
____ is a form of prevention for influenza virus
Influenza virus vaccine is a form of prevention for influenza virus (everyone should get it)
RSV surface proteins are _____ and _____
RSV surface proteins are SH protein and F protein
- SH protein: inhibits apoptosis
- F (fusion) protein: mediates fusion of infected cells together to form syncytia
_____ is the most common cause of lower respiratory tract infection in kids < 1 year old
RSV is the most common cause of lower respiratory tract infection in kids < 1 year old
(also large cause of neonatal death)
RSV is transmitted by ____
RSV is transmitted by respiratory droplets
RSV infection ______ and reinfection is common because _____
RSV infection remains restricted to the lung and reinfection is common because immunity does not persist
RSV symptoms depend on _____ and _____
RSV symptoms depend on age and immunocompromised status
- Older children and adults: rhinorrhea, nasal congestion, sore throat, cough, and fever
- Infants and neonates: pneumonia or bronchiolitis, wheezing and apnea
- Immunocompromised adults: viral pneumonia and secondary bacterial pneumonia
Mainstay of RSV management is _____
Mainstay of RSV management is supportive
- Passive immunity not recommended and benefit of ribavirin is unknown
Parainfluenza virus ______ mediates ______
Parainfluenza virus fusion protein mediates the formation of multinucleated giant cells
Describe the illness caused by the different types of parainfluenza virus
- PIV 1 and 2: croup
- PIV 3: children with lower respiratory tract disease (pneumonia)
- PIV 4: common cold, pneumonia in immunocompromised people
(PIVn 3 is most common)
PIV 1 and 2 cause _____ in children
PIV 1 and 2 cause croup in children
(high mortality in immunocompromised adults)
PIV treatment is ______
PIV treatment is supportive
(no available antiviral has shown efficacy for therapy)
Adenovirus has many _____, which allows it to cause many disparate diseases
Adenovirus has many antigenic serotypes (41), which allows it to cause many disparate diseases
- Types 3, 4, 7, 21: respiratory disease
- Types 8, 19: keratoconjunctivitis
- Types 11, 21: hemorrhagic cystitis
- Types 40, 41: infantile gastroenteritis
Adenovirus is primarily transmitted via the _____ route
Adenovirus is primarily transmitted via the fecal-oral route
(also aerosol droplet and direct inoculation)
Adenovirus causes ______, which is bilateral conjunctivitis followed by development of painful corneal opacities
Adenovirus causes epidemic keratoconjunctivitis, which is bilateral conjunctivitis followed by development of painful corneal opacities
Adenovirus ___ causes sporadic outbreaks, which can be severe disease and pneumonia
Adenovirus 14 causes sporadic outbreaks, which can be severe disease and pneumonia
Most adenovirus infections are _____, so treatment is reserved for those with severe disease
Most adenovirus infections are self-limiting, so treatment is reserved for those with severe disease
- Severe pneumonia or other organ invasive disease are treated
- Cidofivir: nephrotoxic
- Brincidofovir
Vaccine for _____ used by military, not civilians
Vaccine for adenovirus used by military, not civilians
(oral type 4 and 7 vaccine for military recruits)
Rhinovirus has ____, which makes development of a vaccine difficult and explains why the common cold is so common
Rhinovirus has 100 serologic types, which makes development of a vaccine difficult and explains why the common cold is so common
Rhinovirus is transmitted via ____ and _____
Rhinovirus is transmitted via respiratory droplets and contaminated hands or surfaces
Rhinovirus replicates best at ____, so it prefers the _____
Rhinovirus replicates best at 32ºC, so it prefers the nose and conjunctiva
(replicates poorly at body temperature 37ºC, which is why it DOES NOT prefer the lower airway)
There is ______ for rhinovirus
There is no specific therapy for rhinovirus
- Symptom management
- Vitamin C does not prevent common cold but may reduce symptoms
- Zinc therapy may decrease symptoms
Coronavirus is _____ and causes the _____
Coronavirus is ubiquitous and causes the common cold
(has been associated with lower tract disease but unclear if primary pathogen or co-pathogen)
- Non-SARS serotypes include MERS-CoV and 2019-nCoV
- SARS coronvirus: genome sequence different from existing human strains and binds to angiotensin-converting enzyme 2 receptor
The source of his infection is _____ because he has _____
The source of his infection is a civet because he has SARS
Hantavirus cardiopulmonary syndrome is ______
Hantavirus cardiopulmonary syndrome is initial fever followed by the abrupt onset of acute pulmonary edema and shock
SARS-CoV is spread to humans from _____, which receive the virus from ______
SARS-CoV is spread to humans from palm civets, which receive the virus from bats
MERS-CoV is spread to humans from _____, which receive the virus from ______
MERS-CoV is spread to humans from camels, which receive the virus from bats
(high mortality rate)
Most common signs and symptoms of 2019-nCoV are _____ and _____
Most common signs and symptoms of 2019-nCoV are fever and cough
(chest X-ray is best way to diagnose, most severe in males/older/those with comorbidities)
_____ is avian influenza A
H5N1 is avian influenza A
(could be very contagious in humans)
