Flashcards in Week 139 - Communicable diseases III Deck (11):
Describe symptoms of flu
Incubation periof of ussually 2-3 days
Usually resolves in 3-4 days
What are the complications of contracting flu?
- primary influenza pneumonia
- secondary bacterial pneumonia
Worsening of chronic conditions
- Heart failure
How can flu be transmitted?
Large respiratory droplets
- direct airborne
- indirect surface contamination (survive <= 24hours)
- detectable 24 hours before symptom onset
- most contagious first days of symptoms
- falls to low levels by day 5
What is flu?
- RNA virus
- contains 8 different genes that encode for neuraminidase (N) and haemaglutanin (H)
- strain defined by the type of H and N genes
What is antigenic drift?
RNA-dependent RNA polymerases have no proof reading mechanism
=> mistakes (mutations) are made during RNA synthesis
=> mutations are non-lethal and encode altered antigenic proteins
What is antigenic shift?
Infection of the same cell by two different flu types, often from species (i.e. bird and human)
Fragments from different flu types can be packed into a new virus with genes from both "parents"
What is an influenza pandemic and when does it occur?
An epidemic of influenza that spreads on a world wide scale
Occurs when a new influenza virus emerges as a result of antigenic shift, due to human population having no pre-existing immunity
When should anti-virals be used?
If all of the following occur:
- patient in an at risk group
- within 48 hours of flu-like symptoms occuring
- if influenza virus is circulating
Which people are considered at risk?
> 65 years old
Which patients should vaccinations be offered to?
At risk groups who are older than 6 months