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Microbiology Exam 2 > Respiratory Tract Viruses > Flashcards

Respiratory Tract Viruses Flashcards

1
Q

What is the 4th most common cause of death in US?

A

-lower respiratory tract

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2
Q

Who is at greatest risk for acute viral respiratory disease?

A
  • the very young
  • the elderly
  • the chronically ill
  • those with immune compromise
  • *affects all age groups, but these people more so**
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3
Q

Viruses account for _____ or more of RTIs.

A

-80% or more

3-4 per year for an adult and 6-8 for children per year

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4
Q

Viral respiratory illness stats in children and adults

A
  • children: implicated in 40-70% of community-acquired pneumonia; over 90% of bronchiolitis; over 90% of asthma exacerbations
  • adults: 30-50% CAP; 80% or more of asthma exacerbations; 20-60% of exacerbations of COPD
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5
Q

Those infected with a viral respiratory illness are predisposed to what?

A

-a range of secondary bacterial infections in respiratory tract and can precipitate syndromes affecting other organ systems

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6
Q

What is a key feature in acute viral respiratory disease?

A
  • seasonality
  • incidence highest in winter and lowest in summer
  • seen all year round in climates that are not temperate (tropical) and opposite of us in southern hemisphere
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7
Q

The location of infection in respiratory tract is related to _______.

A

-various symptoms

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8
Q

Systemic vs common local manifestations of acute RTI. How often do these last?

A
  • cough, runny nose, sneezing, sore throat, ear pain, congestion
  • fever, headache, chills, malaise, myalgia
  • 7-10 days at most, 2-3 wks in many, longer in some
  • most are acute, mild, and self-limited
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9
Q

In general, common respiratory viruses are distributed world-wide, have a short incubation period, and are transmitted _______________. They have similar pathogenesis (describe it) and are associated with increased risk of ____________. Immunity is _________.

A
  • person to person
  • localized infection and damage to respiratory epithelium
  • bacterial superinfection
  • imperfect so reinfection is common
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10
Q

RV’s are transmitted person to person via ______ and ________ ways. Give examples.

A
  • direct and indirect
  • direct: direct contact with infected person or aerosolizations of infective droplets during coughing and sneezing
  • indirect: hand transfer of contaminated secretions or transfer from contaminated objects to nasal or conjunctival epithelium
  • *spreads very quickly**
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11
Q

Mechanism of RV infection and establishment and host immune responses to try to fight it off.

A
  • virus enters via nose and eyes
  • infect ciliated respiratory epithelial cells lining upper and lower airways where they multiply locally without systemic infection!
  • cytolytic causing cell damage and eventually death; clearance mechanisms compromised
  • Local and circulating antibody release and T cell recognition with release of cytokines and chemokines to recruit neutrophils, NK cells, CD4+ and CD8+ T cells, macrophages, mononuclear cells and eosinophils
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12
Q

Certain viruses interact with immune system to promote _____________ lead to virus-induced wheezing and asthma. This immune-mediated injury has been termed ___________.

A
  • immediate hypersensitivity

- cytokine storm

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13
Q

What is the most common cause of bronchiolitis and pneumonia in infants and children less than 1 year old?

A
  • Respiratory Syncytial virus (RSV)

- single most important agent of respiratory disease in infancy

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14
Q

What family does RSV below to? Describe the structure of this virus. Is it associated with any unique surface proteins or antigenic types?

A
  • paramyxovirus
  • enveloped; single stranded (-) RNA
  • G and F proteins: G for attachment, F for fusion
  • antigenic types A and B
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15
Q

Due to RSV’s genomic structure, what must it contain?

A

-RNA-dependent RNA polymerase to turn the -RNA into +RNA

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16
Q

RSV was named for it syncytial ability; what protein mediates this?

A

-F protein mediated fusion of cells

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17
Q

Source of RSV infection? What is the peak age of contracting this? Why are reinfections common?

A
  • humans are the only source of infection; sizeable community outbreaks occur
  • virtually all children infected by 2-3 years old with age peak of 2-5 months
  • reinfections common for all age groups bc immunity is imperfect and not completely cross protective against the 2 strains–CAN BE REINFECTED IN SAME SEASON
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18
Q

What is the only respiratory pathogen capable of causing sizeable outbreaks?

A

-RSV

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19
Q

Who goes on to develop very serious RSV illness? What is the mortality in impaired host?

A
  • very young infants, especially premature infants

- children 15% in impaired host

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20
Q

Of infants <1 y.o. who contract RSV, what percentage die?

A
  • 80%

- leading viral cause of mortality in infancy

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21
Q

T/F: Most children with RSV infections are previously healthy and therefore, are often asymptomatic.

A

-false, only 0.3% are asymptomatic

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22
Q

What is the most classic illness associated with RSV infection in children? Second most classic?

A
  • Bronchiolitis

- pneumonia

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23
Q

Symptoms of RSV disease in children 1 year and under in URI, LRI, and other areas infection is seen to affect. What do the lungs look like?

A
  • URI: cough, rhinitis, pharyngitis, fever
  • LRI: expiratory wheezing, air-trapping tachpnea, dyspnea, rales, rhonchi, retractions, nasal flaring, grunting, hypoxemia, irritability, dehydration, and respiratory distress; HYPER EXPANSION OF LUNGS and hypercapnia
  • Other: otitis, vomiting, conjunctivitis
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24
Q

How long does RSV disease usually last?

A

-10-14 days

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25
Q

What is the pathological effect of RSV due to?

A

-direct viral invasion of respiratory epithelium which is followed by immunologically mediated cell injury

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26
Q

What causes the breathing sounds associated with RSV? Compare rales to rhonchi.

A
  • necrosis of the bronchi and bronchioles leads to formation of plugs of mucus, fibrin, and necrotic material within smaller airways which are readily obstructed
  • rales: crackling in lower lung due to airways popping throug exudate
  • rhonchi: courser sounding and higher up in lungs
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27
Q

What are retractions and what do they signify?

A
  • they are inward muscle pulls usually associated with areas near the ribcage
  • usually sign of breathing troubles
28
Q

If one were to look at a Chest Xray of a child with RSV bronchitis, what are some key features that one could expect to see? If we took a blood test, would we expect to see RSV in the blood?

A
  • hyperinflation of lungs
  • flattened diaphragm with horizontal ribs
  • increased hilar bronchial markings
  • No; infection localized to respiratory tract and not associated with viremia
29
Q

Adult RSV infections: what are they like? who are they serious in? and what characteristics of patients should be watch out for?

A
  • frequent in healthy adults; mild, influenza-like illness
  • serious in elderly and patients with congestive heart failure, bronchipulmonary insufficiency, and immune suppression
  • should suspect RSV in all adults who present with fever and pulmonary infiltrates bc it is over overlooked as a cause of death among elderly via pneumonia
30
Q

Grandparents may get RSV from their grandchildren, but where else is a huge concern of contracting this virus? What can help stop this spread?

A
  • hospital!!
  • major concern in pediatric wards, nurseries, nursing homes, and adult medical wards
  • control spread by careful attention to proper hand washing and infection control guidelines necessary; NO VACCINE!!!
31
Q

Discuss how long RSV can survive on surfaces.

A
  • 3-30 hours on counter tops
  • cloth gowns, gloves, tissue for 1 hour
  • skin for 30 minutes
32
Q

RSV treatment

A
  • usually supporting and used to maintain hydration and oxygenation, keep airways clear of mucus and debris
  • Palivizumab (Synagis): humanized mouse monoclonal antibody for high risk-children
  • aerosolized ribavirin for RSV LRTI
33
Q

How is Palivizumab (Synagis) administered? What is it used for? What are issues with aerosolized ribavirin?

A
  • both drugs for RSV
  • Synagis: IM injection 1/month during RSV season (usually 5 doses); used to prevent RSV LRTI in selected infants and children
  • Ribavirin is a teratogen!!!
34
Q

What family does Parainfluenza virus belong to? Describe their unique proteins and structure.

A
  • Paramyxovirus (with RSV, HMPV, mumps and measles)
  • enveloped virus
  • nonsegmented, ss RNA genome (-) sense
  • envelope has 2 glycoproteins: HN protein with hemagglutinin and neuriminidase activity and F (fusion) protein
35
Q

3 differences between Parainfluenza and Influenza

A
  • Para’s RNA synthesis occurs in cytoplasm, not nucleus
  • RNA genome is not segments
  • hemagglutinin and neuraminidase activity are combined into 1 protein
36
Q

Where does Parainfluenza most typically cause disease?

A
  • larger airways of LRT

- important cause of LRTI in infants and children

37
Q

Discuss the antigenic types of Parainfluenza and what they differ in.

A
  • 4 serotypes; 1,2,3,4

- differ in frequency of occurrence, disease spectrum, and epidemic patterns

38
Q

Multiple PIV serotypes and short duration of immunity make reinfection common, but subsequent infections tend to be ____________.

A

-less severe

39
Q

List 4 common diseases due to PIV, which serotypes causes them, who they mainly cause them in, and what season they occur.

A
  1. Croup: due to virus 1 and 2 (mainly 1); 6-12 months old; autumn
    2-3.Bronchiolitis, pneumonia: due to virus 3, infants less than 6 months old, endemic (spring)
  2. URI: virus 4; children; endemic
40
Q

How does croup begin? What causes it commonly?

A
  • virus infects epithelial cells of upper airways
  • begins as URI with thin nasal discharge, sore throat, mild cough
  • within 1-2 d, inspiratory stridor, retractions, worsening barking cough (hoarseness)
41
Q

What is the classic “steeple sign” associated with and what causes it?

A
  • PIV infected xray

- hoarseness due to narrowing in region of larynx and subglottic trachea

42
Q

Symptoms of croup result from _____________. What is a hallmark of the disease? who does it affect? when does it occur? when does it get worse? how long does it last? how do you treat it?

A
  • inflamed larynx and subglottic airway; may close in severe case
  • dry-barking (seal-like) cough is hallmark
  • affects children 6mos to 12 y.o. and peaks at 2 years; more common in boys than girls
  • most causes occur in fall or early winter
  • worsens at night
  • self -limited condition lasting 3-7 days, 7-14 days in some
  • Tx: if mild disease, supportive therapy; if severe, use O2, nebulized epi, and corticosteroids
43
Q

Describe adenovirus structure and how this influences tropism

A
  • nonenveloped
  • icosahedral capsid of hexon and penton capsomers
  • dsDNA geomes
  • fibers project from capsid at penton base and are major attachment proteins
  • penton base and fiber proteins determine serotypes, tissue tropism, and disease
44
Q

Where does adenovirus replication and assembly occur?

A

-nucleus

45
Q

There are ~______ types of adenovirus and belong to species _________. What species cause what areas of infection?

A
  • 100 (57 infect humans)
  • A-G (varied tissue tropism)
  • Mainly B and C, some E infect RT
  • B and D are ocular
  • Primarily F, some A and G cause GI disease
46
Q

Adenoviruses are characterized by their ________________. What percentage of infection result in disease?

A
  • ubiquity and persistence in host tissues

- 45%

47
Q

Adenovirus epidemiology: be sure to include who is most commonly infected, and how it is spread.

A
  • endemic in US throughout year with sporadic outbreaks with no predictability ***
  • epidemics occur in military recruits (4 and 7)
  • infections most common in children from 6 mos- 5 years old, but also seen in grade school and junior high school
  • spread by respiratory and fecal route via aerosols, fingers, fomites, poorly chlorinated swimming pools
48
Q

Although infections with adenoviruses occur in all age groups, the overall incidence is _________ related to age.

A
  • inversely

- predilection for infants and children between 6 mos and 5 years of age

49
Q

If you see exudative pharyngitis, what 3 pathogens are you thinking?

A
  • EBV
  • GAS
  • Adenovirus
50
Q

Why are adenoviruses associated with so many syndromes?

A

-there are a ton of types of this virus and they have different tropisms

51
Q

Discuss the clinical presentations of adenoviruses you see of the following groups of people: infants and young children, school-aged children, military recruits, transplant recipients/AIDS patients/ other immunocompromised

A
  1. infants, young children: acute febrile pharyngitis, pneumonia, pertussis-like syndrome
  2. School-aged children: pharyngoconjunctivial fever
  3. military: acute respiratory disease
  4. Immunocompromised: disseminated disease (hepatitis, pneumonia), acute hemorrhagic cystitis
52
Q

Adenoviruses and herpes can both cause what eye condition?

A

-keratoconjunctivitis which can impact the cornea

53
Q

What family of virus does rhinovirus belong to? Genus? Describe its structure and how it attaches to cells

A
  • Picornaviridae family: small ssRNA virus; genus: enterovirus
  • naked nucleocapsid with 4 viral proteins VP1-4 that attach to intracellular adhesion molecule-1 (ICAM-1)
54
Q

What is the most commonly identified virus from persons experiencing acute respiratory illness?

A

-Rhinovirus; affects all age groups

55
Q

How are rhinoviruses organized?

A
  • > 100 serotypes/genotypes in 3 groups (A-C)
  • 3-4 circulate at a time
    • known for antigenic diversity**
56
Q

What is the common cold virus and what does it attach to on host cells?

A
  • rhino virus

- ICAM-1

57
Q

What is competitively inhibit of rhinovirus for ICAM-1?

A
  • Zinc

- hence treatments like Zicam

58
Q

Rhinovirus can cause more serious disease that is completely under appreciated by medical community. Name such issues

A
  • LRTI more common than thought
  • can cause significant flu-like illness
  • plays major role in significant resp. illnesses like bronchiolitis in infancy, childhood pneumonia, and exacerbate chronic respiratory diseases
59
Q

Characteristics of coronavirus

A
  • enveloped
  • positive sense ssRNA
  • distint petal or club shaped spikes called solar corona: created by spike protein peplomers
  • infects respiratory and GI tracts of mammals and birds
  • 4 resp. serotypes
60
Q

Like rhinoviruses, coronaviruses can cause more serious ________.

A

-LRTI

61
Q

Clinical diseases associated with coronavirus

A
  • 10-30% of common colds
  • serious LRTI
  • can also cause enteric, hepatic, or neurologic diseases
62
Q

Where can coronavirus be found, aside from humans?

A
  • birds, cats, dogs, pigs, mice, horses, and whales

- bats

63
Q

What family does Human Metapneumovirus (hMPV) belong to? Describe this virus and morphology.

A
  • paramyxovirus
  • found in all age groups
  • pleomorphic particles
  • ssRNA
  • enveloped
  • NO hemagglutin
  • 2 major groups and 4 genotypes
  • most closely related to bird metapneumovirus
64
Q

hMPV epidemiology and disease: what other virus is it similar to clinically? who gets it? what are the clinical presentations?

A
  • similar to RSV
  • linked to acute respiratory illnesses in children, elderly, and those with underlying immune compromise and cardiopulmonary disease
  • all children infected from 5-10 y.o. but new infections occur throughout life
  • range from URI to severe bronchiolitis and pneumonia
65
Q

What are some possible complications of a RVI?

A
  • exacerbation of underlying respiratory disease
  • development of chronic lung disease
  • possible secondary bacterial infections
  • acute otitis media
  • apnea, respiratory failure
  • SIDS
66
Q

What form of immunity is likely to be pivortal in clearance of RVI’s and in recovery?

A
  • cell-mediated immunity

- illness is milder with reinfections

67
Q

4 common ways to diagnose respiratory viruses

A
  • clinical and epidemiological findings
  • viral culture
  • rapid antigen detection
  • detection of nucleic acids

Microbiology Exam 2 (11 decks)

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