Emerging infectious threats

Question 1

What contributes to new host vectors

Answer 1

• Global warming
• Agriculture and irritation
• Urbanisation
• Social changes
• Immunosuppression
• IV drug user

Question 2

What test is used in a legionella outbreak

Answer 2

• Urinary antigen test - this is how you distinguish it from other pneumonias - you will find the serogroup 1 antigen
• Also serology (for antibody too) and resp tract culture

Question 3

What are the features of E.Coli and what cultures must be done if suspected

Answer 3

• Can cause haemolytic uraemia syndrome

- Culture faeces and indentify 0157:H7

Question 4

What are the 3 main antibiotic resistant infections

Answer 4

1. MRSA - Methicillin resistant staph aureus
2. ESBL- Extended spectrum beta lactamase producers - coliform organisms resistant to 3rd gen cephalosporins- ICU problem
3. VRE- Vancomycin resistant enterococcus - affects immunocompromised

Question 5

What are the 3 main health care associated infections

Answer 5

• Antibiotic resistant organisms
• Clonstridium difficile- enteric infection with diarrhoea
• Norovirus (winter vomiting)

Question 6

Discuss the various types of influenza

Answer 6

• Seasonal influenza - type A or B- common cold every winter
• Avian influenza - type A - disease of birds , closely related to human influenza virus
• Pandemic influenza- high morality

Question 7

Discuss the features of human influenza

Answer 7

• Influenza A- birds and mammals affected
  - Lots of types H3N2, H1N1 etc
  - Nucleocapsid- segmented RNA genome - each gene is on a separate molecule of negative strand RNA - important in its evolution
  - Has 2 glycoproteins- N and H these are the parts of the virus that change

Influenza B - humans only

Question 8

What is antigenic shift

Answer 8

-Happens infrequently, will cause complete change in H protein to a different protein so nobody has prior immunity to the virus - causing a pandemic

Question 9

What is antigenic drift

Answer 9

Happens continuously with influenza A- slow accumulation of H protein causes the virus to change throughout flu season and year to year - why we have to change the flu vaccine

Question 10

Describe reassortment/ segment mixing

Answer 10

• Genetic reassortment- a combination of 2 viruses that has produced 1 virus with components from both parents
• Human virus+ bird virus can infect human cells but has bird antigens that human has no prior immunity to- causes pandemic

Question 11

What receptors do humans birds and pigs have

Answer 11

Humans- alpha 2 and 6 receptor
Birds- Alpha 2 and 3 receptors
Pigs- Alpha 2 and 6 and alpha 2 and 3 receptors - infection most likely to go through this

Question 12

What is the definition of a pandemic

Answer 12

Widespread epidemic that affects a whole country/ continent , then a pandemic flu will become a seasonal flu and stay one each year until repeated by another pandemic

Question 13

Discuss the features of swine flu

Answer 13

• 2009 mexico - reassortment of 3 pig adapted viruses
• Younger age distribution
• Asymptomatic in children
• Risk factors- pregnancy, obesity , neurodevelopment delay

Question 14

Discuss the features of SARS

Answer 14

• Severe acute respiratory distress syndrome
• The 3 SARS signs = -Fever - Dry cough -Rapid progression to resp failure
• Severe in older people
• High cases in healthcare workers
• Described as an atypical pneumonia
• Zoonotic coronavirus