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
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
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
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
5
Q
How can RSV be treated?
A
- Antivirals e.g ribivarin - in complicated cases
- IV immunoglobulin in specific cases
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
7
Q
Describe coronavirus.
A
- Second most common cause of common cold
- Milder infection
- 50% - asymptomatic. EXCEPTION - COVID-19
- RNA Virus from Coronaviridae family
8
Q
Describe SARS CoV
A
- Fever > 38 degrees
- Respiratory symptoms, SOB
- CXR, with pneumonia
- Droplet, contact spread
- Detected by PCR and cell culturing
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
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
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
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
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
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
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
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
