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Karan - MBBS Year 1: Respiratory Week 4 > Respiratory Infections - Viruses > Flashcards

Respiratory Infections - Viruses Flashcards

1
Q

When do the following respiratory viruses peak?
- RSV
- Rhinovirus

A
  • RSV - peak in October/November
  • Rhinovirus - spike in admissions in September continuing throughout winter
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2
Q

What viruses are linked to the following conditions
- Bronchiolitis
- Croup
- Upper respiratory tract infections
- Tonsilitis
- Pneumonia
- Infectious mononucleosis

A
  • BRONCHIOLITIS- RSV/Parainfluenza/adenovirus
  • CROUP - RSV/(para)influenza virus
  • URTI - All aforementioned + rhinovirus and coronavirus
  • TONSILITIS - EBV and adenovirus
  • Pneumonia - (para)influenza, adenovirus, RSV
  • Infectious mononucleosis - EBV and CMV
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3
Q

Describe respiratory syncytial viruses

A
  • LRTI in young children - bronchiolitis - usually in children under 12 months. Wheezing and increased respiratory rate. Cyanosis in severe cases. PNEUMONIA
  • URTI in adults - common cold. Pneumonia in elderly
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4
Q

What are the main characteristics of respiratory syncytial virus?

A
  • Causes mild cold like symptoms in older healthy children/adults
  • Annual epidemic during winter months in temperate clinics
  • More common in rainy season during tropical climates
  • Re-infection can occur
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5
Q

How can RSV be treated?

A
  • Antivirals e.g ribivarin - in complicated cases
  • IV immunoglobulin in specific cases
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6
Q

Describe rhinovirus.

A
  • Most frequent cause of common cold
  • Droplet spread and limited to URT
  • RNA virus from Picornaviridae family
  • Detected by PCR
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7
Q

Describe coronavirus.

A
  • Second most common cause of common cold
  • Milder infection
  • 50% - asymptomatic. EXCEPTION - COVID-19
  • RNA Virus from Coronaviridae family
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8
Q

Describe SARS CoV

A
  • Fever > 38 degrees
  • Respiratory symptoms, SOB
  • CXR, with pneumonia
  • Droplet, contact spread
  • Detected by PCR and cell culturing
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9
Q

Describe MERS-CoV

A
  • Typical symptoms - fever, cough and SOB
  • Pneumonia - common - not always present
  • GI symptoms may occur
  • High mortality
  • Attributed to human-animal interactions
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10
Q

Describe pathogenesis of patients with SARS CoV-2

A
  • Viral entry
  • Initial immune responses attracts viral specific T cells to site of infection
  • Infected cells eliminated before virus can spread. Recovery
  • In sever cases, aberrant immune response
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11
Q

Describe adenovirus.

A
  • Droplet and contact transmission
  • Usually causes URTI
  • 50% of infections - asymptomatic
  • Occasionally severe bronchopneumonia in infants
  • DNA virus
  • Viral antigen detection by PCR
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12
Q

Describe metapneumovirus.

A
  • Related to RSV
  • Infections in infants, young children
  • Mild URTI, can lead to bronchiolitis and pneumonia
  • Diagnosed in lab by serology and PCR
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13
Q

Describe parainfluenza

A
  • Major cause of croup, pneumonia and bronchiolitis
  • 4 serotypes
  • Droplet/contact spread
  • RNA virus from Paramyxoviridae family
  • Diagnosed in lab by PCR antigen detection
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14
Q

Describe Influenza A and B

A
  • Influenza A - outbreaks occur - causing epidemics. Multiply and spread between animals - example are brids
  • Influenza B - less severe disease and smaller outbreaks. Predominantly found in humans and burden of disease mostly in children
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15
Q

Describe influenza virus

A
  • Causes illness in all age groups
  • Transmitted by aerosols
  • Sudden onset
  • Diagnosed in lab by PCR
  • Causes fever, chills and myalgia
  • Complications - secondary bacterial pneumonia, rarely viral pneumonia, myocarditis
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16
Q

Describe the structure of the Influenza A virus.

A
  • Genetic material (RNA) in centre
  • 2 surface antigens - neuraminidase and haemagglutinin
  • Haemagglutinin - bind to cells of infected person via receptors
  • Neuraminidase - release virus from cell surface
17
Q

Describe the pathogenesis for Influenza.

A
  • Haemagglutinin - allows viral attachment
  • Virus transported into cytoplasma
  • M2 proteins opened - influx of H+ ions into virus
  • Causes uncoating
  • Neuraminidase - digests neuraminic acid in mucus - facilitates viral spread
18
Q

Describe the two types of genetic changes in influenza.

A
  • ANTIGENIC DRIFT - natural mutations in genes of flu viruses. Occur gradually over time
  • ANTIGENIC SHIFT - two or more strains combine - forms new subtype. Imunity from previous infections/vaccinations are ineffective
19
Q

What are the features of influenza?

A
  • Easily transmitted by droplets, aerosols, hand to mouth/eye contamination from contaminated surfaces
  • People with mild or no symptoms can infect others
  • Incubation period (average 2-3 DAYS) - longer in people with immune deficiency
  • SYMPTOMS - sudden onset of fever, chills, headaches, fatigue, muscle and joint pain, sore throat, dry cough
20
Q

What are some possible complications of influenza?

A
  • COMMON - bronchitis, sinusitis, secondary bacterial pneumonia
  • LESS COMMON - meningitis, encephalitis, primary influenza pneumonia
21
Q

Who is most at risk of serious complications in influenza?

A
  • Elderly
  • Pregnant women
  • Older people
  • People with underlying health conditions
22
Q

Give two examples of anti-virals used against flu.

A
  • Ion channel blocker e.g amantadine and rimantidine
  • Neuramidase inhibitor e.g zanamivir, oseltamivir
23
Q

Describe the types of influenza vaccine.

A
  • INACTIVATED - injection
  • LIVE ATTENUATED - nasally
  • TRIVALENT - 2 subtypes of influenza A and one type B
  • QUADRIVALENT - same as trivalent but one extra type B
24
Q

Why is the intranasal vaccine offered to children aged 2 years and over, a quadrivalent vaccine?

A
  • Contain both lineages of B viruses
  • Better protection against circulating B strains
25
Q

Describe the mechanism of action of COVID vaccines

A
  • mRNA vaccines target S protein
  • Exploit host cells to translate code and synthesise target spikje protein
  • Protein acts as intracellular antigen - stimulate immune response
  • mRNA degraded within few days

Karan - MBBS Year 1: Respiratory Week 4 (12 decks)

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