Week 139 - Communicable diseases III

Question 1

Describe symptoms of flu

Answer 1

Incubation periof of ussually 2-3 days

Sudden onset

Usually resolves in 3-4 days

Question 2

What are the complications of contracting flu?

Answer 2

Respiratory

• primary influenza pneumonia
• secondary bacterial pneumonia

Worsening of chronic conditions

• COPD
• Asthma
• Heart failure

Myocarditis

Pericarditis

Encepalopathy

GB-Syndrome

Question 3

How can flu be transmitted?

Answer 3

Large respiratory droplets

• direct airborne
• indirect surface contamination (survive <= 24hours)

Virus sheddings

• detectable 24 hours before symptom onset
• most contagious first days of symptoms
• falls to low levels by day 5

Question 4

What is flu?

Answer 4

Inflenza virus

• RNA virus
• contains 8 different genes that encode for neuraminidase (N) and haemaglutanin (H)
• strain defined by the type of H and N genes

Question 5

What is antigenic drift?

Answer 5

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

Question 6

What is antigenic shift?

Answer 6

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”

Question 7

What is an influenza pandemic and when does it occur?

Answer 7

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

Question 8

When should anti-virals be used?

Answer 8

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

Question 9

Which people are considered at risk?

Answer 9

> 65 years old

Chronic conditions

Immunosuppressed

Pregnancy

Question 10

Which patients should vaccinations be offered to?

Answer 10

At risk groups who are older than 6 months

Question 11

When should antivirals be used as prophylaxis?

Answer 11

If all of the following apply:

• someone has “flu-like” symptoms likely caused by flu
• an at risk patient
• been in contact with patient with flu <48 hours