Respiratory viruses Flashcards
How may resp viruses be transimitted?
Direct inhalation of resp droplets.
Indirectly via fomites.
Examples of viruses transmitted in droplets?
Influenza, rhinovirus, adenovirus
Difference between influenza and the common cold?
Influenza is more severe and patient may be systemically ill.
Viruses causing the common cold?
Corona viruses, rhinoviruses, adenoviruses
Features of influenza A virus?
Infects many mammals and avian species.
Includes Seasonal influenza- Causes disease in humans. Doesnt cause disease in birds.
Includes Avian influenza- Causes disease in birds but rarely in humans.
Features of influenza B and C?
Both restricted to humans.
Influenza B has outbreaks every 2-4 years, but not pandemics.
Influenza C is rarer and causes milder disease.
How are influenza viruses classified?
By A,B, or C.
By haemaglutinin (HA) and neuroaminidase (NA).
e.g, H1N1= Swine flu
What is antigenic drift?
Minor changes in transcription leading to slightly different surface proteins/glycoproteins.
Leads to yearly epidemics seen in influenza.
What is antigenic shift?
Major changes where genes are swapped between organisms, forming a new strain.
Seen when two diff strains simultaneously infects the same host cell.
MAY LEAD TO PANDEMICS.
Function of HA in influenza?
Binds to receptors on host cells.
Function of NA in influenza?
Cleaves sialic acid in resp epithelium. Allows the virus to be released from the cell and prevents clumping.
Clinical features of influenza infection?
Acute onset of fever, myalgia and cough. Persistent weakness and depression.
Complications of influenza?
Primary influenza pneumonia Secondary bacterial pneumonia Myositis or myocarditis CNS conditions Reye's syndrome Death
How do you treat influenza?
Supportive (Antipyretics and analgesics) Anti-virals - Oseltamivir (PO or NG) - Zanamivir (inhaled) Advise annual vaccination Oxygen if hospitalised
What type of viral infection is an RSV infection?
LRTI
