Lecture 20 - epidimiology

Question 1

what is an endemic

Answer 1

constantly present
low level frq of disease at regular intervals
e.g. colds, human flu

Question 2

what is an epidemic

Answer 2

sudden increase above expected rates of disease

Question 3

pandemic

Answer 3

increase simultaneously over a wide area (global)

Question 4

what were the 4 flu pandemics since 20th C

Answer 4

spanish flu
asian flu
hong kong flu
swine flu

Question 5

what disease wiped out all the froggys

Answer 5

chytridiomycosis panzootic
a fungal disease

Question 6

some examples of plant pandemics

Answer 6

• maize lethal necrosis
• rice tungro
• sweet potato virus
• banana bunchy top wtf
• plum pox

Question 7

what are the 2 things that need to be measured to measure frq of infection

Answer 7

• morbitity rate = no. becoming ill
• mortality rate = % those ill dying

Question 8

how many cases classes an epidemic

Answer 8

over 400cases per 100k population per week

Question 9

what are the 2 types of epidemic

Answer 9

• common source epidemic = sharp rise, sharp decline
• propagated epidemic = slow rise and slow decline

Question 10

an example of common source epidemic

Answer 10

legionnaires disease (collecting towers bact, infects people)

Question 11

what is herd immunity

Answer 11

resistance of a population to infection due to immunity of the majority

Question 12

how many % people need to be immunised for herd immunity to flu

Answer 12

90%
cuz highly contagious

Question 13

why might even a 90-95% vaccinated pop (the required for herd immunity) still not be protected from measles

Answer 13

might not be an even distribution across the pop

Question 14

how many people need to be susceptible (un vaccinated) for measles to be sustained in a community

Answer 14

250-300K

Question 15

what is antigenic drift

Answer 15

minor antigenic variation sue to mutations

Question 16

what are the 2 antigen types on flu virus

Answer 16

haemagglutinin and neuraminidase

Question 17

actual name of influenza virus

Answer 17

orthomyxovirus

Question 18

diff between antigenic shift and drift

Answer 18

drift is accumulation of minor mutatitions
shift is mixture of genes in influenza virus

Question 19

how does antigenic shift occur in flu

Answer 19

2 strains infect same cell
in cel form diff H and N combo
ta da new strain

Question 20

what strain resulted in Mexico 2009 after antigenic shift

Answer 20

H1N1
caused lots of deaths
mix between human pig and bird flu

Question 21

3 types of control measures taken in epidemic

Answer 21

eliminate source
break connection between source and host
raise level of herd immunity

Question 22

what are examples of emerging diseases

Answer 22

emerging is NEW
- HIV
- Ebola
- Legionnaires disease
- E.coli O157
- Zika

Question 23

what ways can zika virus be transmitted

Answer 23

• mosquito vector
• sexual transmission
• blood transfusion
• vertical transmission (preg mum to baby
  = birth defects

Question 24

what type of virus are all emerging viruses

Answer 24

RNA viruses
becuase
easily mutate

Question 25

what are 3 diseases that have shown reemergence

Answer 25

TB
Diptheria
hospital acquired infections - MRSA (due to rise in antibiotic resistance)

Question 26

what are some reasons for emergence of new pathogens and remergence of old ones

Answer 26

• more city living = crowded
• bulk processing and transportation
• changes in land use e.g. dams = mosquitos
• international travel
• microbial mutations
• bad weather causing public health measure breakdown
• biological warfare