Viral Respiratory Tract Infections Flashcards

1
Q

URTI

A

Upper Respiratory Tract Infections

Very common, often viral
Can predispose patient to secondary more severe illness

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2
Q

Rhinitis

A

Congestion in nose

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3
Q

Coryza

A

Common Cold

Rhinoviruses
Parainfluenzas
Coronaviruses
Respiratory Syncytial Viruses (RSV)
Adenoviruses
Enteroviruses
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4
Q

Pathogen(s) responsible for Pharyngitis/Tonsilitis

A

Caused by viruses or bacteria

Bacteria is: Strep pyogenes

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5
Q

Infectious mononucleosis

A

Glandular Fever

Syndrome

Pharyngitis, lymphadenopathy, fever, malaise

Atypical mononuclear cells in peripheral blood

Can be caused by Epstein-barr virus, cytomegalovirus (CMV), toxoplamosis, HIV

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6
Q

Syndrome

A

Constellation of symptoms and signs, not an aetiological diagnosis

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7
Q

Croup

A

Seen in young children, characterised by wheeze due to narrowed airways

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8
Q

Epiglottitis

A

Bacterial

potentially life-threatening

Largely caused by an influenza virus

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9
Q

LRTI

A

Lower Respiratory Tract Infections

Influenza
Respiratory syncytial virus
SARS-CoV-2

Rarely:
CMV
Varicella
Measles
MERS/SARS
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10
Q

Types and Subtypes of Influenza viruses

A

A, B or C
- on basis of internal proteins; nuclear and matrix proteins

Subtypes - A only
On basis of surface proteins HA, NA (Haemagglutinin & Neuraminidase)

16HA, 9NA known - each differs by >20% sequence

e.g. A/Sydney/99/3 (H3N2)

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11
Q

Flu-like illness

A

2 Major components

  • Respiratory tract symptoms, e.g. rhinitis/cough/shortness of breath
  • Systemic symptoms, e.g. fever/headache/myalgia
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12
Q

Pathogenesis of influenza

A

Pneumotropic virus - infects cells of respiratory tract/alveoli
Cytolytic/cytocidal
Infection strips off respiratory epithelium

Sputum has rounded up dead epithelia

Removes 2 innate defence mechanisms - mucous secreting cells and cilia

Causes interferon production - Circulates in blood and causes systemic symptoms

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13
Q

Complications of influenza

A

Pneumonia

  • Primary influenza pneumonia - mononuclear cell infiltrate
  • Secondary bacterial pneumonia - granulocyte infiltrate

Cardiovascular complications

CNS complications
- Encephalitis

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14
Q

High risk patients for influenza

A

Those with comorbidities

  • Lung disease
  • Cardiac disease
  • Renal disease
  • Endocrine disease/diabetes
  • Liver disease
  • Immunodeficiency
  • > 65 years
  • Pregnancy/young children
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15
Q

Influenza epidemiology

A

Annual winter epidemics associated with excess deaths, hospitalisations and other serious consequences

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16
Q

Antigenic Drift

A

Occurs in influenza A and B

Accumulation of mutations in a virus in certain regions (HA and NA specifically)

The epitopes are the parts that the immune system forms immunity to but is also the part that the virus mutates rapidly, allowing for rapid reinfection

17
Q

Antigenic shift

A

Remember this vs antigenic drift because it’s worse so you go like oh shi(f)t

Virus mixes with animal/other virus to make a new subtype with antigens we are drastically unfamiliar with that are far more infectious; can cause pandemics

18
Q

H1N1pdm

A

Swine flu; came from antigenic shift of eurasian and north american swine that are almost 20% different to human HA and NA

Influenza A

19
Q

How are annual influenza (flu) vaccines made

A

Scientists look at the most prominent influenza viruses in the southern hemisphere to predict which are about to infect the northern that year, then make the according vaccine; and vice versa

20
Q

RSV

A

Respiratory Syncytial Virus

Enveloped parmyxovirus (dont need to remember)

negative ssRNA eoncdes 9 polypeptides, including 2 surface proteins - F, G

Highly seasonal (winter)

Extremely common; global infection by age 2

21
Q

Disease of RSV

A

LRTI in infants - bronchiolitis, pneumonia

High hospitalisation

Low mortality - unless comorbid

Nosocomially transmitted

Re-infections occur throughout life due to antigenic drift

22
Q

Nosocomial transmission

A

Infections transmitted around hospitals