Community acquired infections

Question 1

communicable diseases can be transmitted from….

Answer 1

• non-human source to humans - from person to person (directly or indirectly)

Question 2

communicable diseases can be transmitted from….

Answer 2

• non-human source to humans - from person to person (directly or indirectly)

Question 3

Source of disease example

Answer 3

• Environmental- legionella pneumophilia
• Food/ water- food poisoning organisms (onwards transmission possible)
• animlas- e.g. rabies- onwards transmission possible

Question 4

endemic disease

Answer 4

usual background rate

Question 5

outbreak

Answer 5

two or more cases linked in time and place

Question 6

epidemic

Answer 6

a rate of ifnection greater than the usual background rate

Question 7

pandemic

Answer 7

very high rate of infection spreading across many regions, countries and continents

Question 8

exampel of persons to person direct transmission

Answer 8

• Influenza (can also get from animal)
• Norovirus
• Neisseria gonorrhoea

Question 9

Person- to person indirect transmission

Answer 9

e.g. mosquito- malaria

Question 10

Basic reproduction number R0

Answer 10

the average number of cases one case generates over the course of its infectious period, in an otherwise uninfected, non-immune population

Question 11

if R₀ is >1

Answer 11

increase in cases

Question 12

R₀=

Answer 12

stable number of cases

Question 13

R₀<1

Answer 13

decrease in cases

Question 14

reasons for outbreaks, epidemic, pandemics

Answer 14

1) New pathogens
2) New hosts
3) New practice

Question 15

New pathogens

Answer 15

• New antigens
• New virulence factors
• New antibacterial resistance

Question 16

New host

Answer 16

• Non-immunes
  
  • E.g. outbreak of chickenpox in children (immune naïve)
• Healthcare effects

Question 17

new practice (social, healthcare)

Answer 17

e. g. feeding cows cows- BSE
e. g. popularity of tatoos increase

Question 18

infectious dose is a factor which determines

Answer 18

which determines a disease transmissibility

Question 19

what is infectious dose

Answer 19

Number of micro-organisms required to cause infection

Question 20

infectious dose varies by

Answer 20

• micro-organism
• presentation of micro-organism
• immunity of potential host

Question 21

stochastic natures of small scale outbreak

Answer 21

Stochastic- represents the element of luck

Question 22

interventions related to the pathogen

Answer 22

• Reduce/eradicate pathogen (only ever been properly achieved with smallpox)
  
  • Antibacterial including disinfectants
  • Decontamination
  • Sterilisation
• Reduce/eradicate vectorEliminate vector breeding sites
  
  • E.g. eliminating malaria breeding sites

Question 23

interventions related to patient

Answer 23

• Improve health
  
  • Nutrition
  • Housing
  • Medical treatment
• Immunity
  
  • Passive e.g. maternal antibody, intravenous immunoglobulin
  • Active i.e. vaccination

Question 24

interventions related to practice

Answer 24

• Avoidance of pathogen or its vector
  
  • Geographic- don’t go there
  • Protective clothing and equipment
  • Long sleeves, trousers against mosquito
  • Personal protective equipment in hospital (gowns, gloves masks)
• Behaviour
  
  • Safe sex
  • Sade disposal of sharps
  • Food and drink preparation

Question 25

interventions related to places

Answer 25

Environmental engineering

• Safe water and air
• Good quality of housing
• Well designed healthcare facilities

Question 26

Vaccination and heard immunity

How vaccinating a proportion of the population can prevent transmission of a disease, including those not vaccinated

Answer 26

Question 27

Consequences of control over infectious disease: good

Answer 27

Decreased incidence or elimination of disease/organisms

• Smallpox
• Polio
• Dracunculiasis (worm infection)

Question 28

Consequences of control over infectious disease: bad

Answer 28

• Decreased exposure to pathogen à decreased immune stimulus –> decreased antibody à increased susceptible à outbreak
• Later average age of exposureà increased severity
  
  • E.g. polio
  • Hepatitis A
  • Chicken pox
  • Congenital rubella syndrome