Epidemiology (6) (Dan Frank)

Question 1

vehicle transmission of pathogen

Answer 1

single point source like food/cyanide poisoning

Question 2

DALYs

Answer 2

disability adjusted life year
number of healthy years of life lost due to premature death/disability
combination of morbidity and mortality

Question 3

Bubonic plague

Answer 3

infects lymphatic system
least serious
painful lymph nodes
30% mortality

Question 4

Septicaemic plaguq

Answer 4

infects blood
most serious
necrosis - black skin
100% mortality

Question 5

Pneumonic plague

Answer 5

lungs
chest pain, cough
80% mortality
only one that is transmissible between humans

Question 6

incidence

Answer 6

number of cases

Question 7

prevalence

Answer 7

total infected in population

Question 8

vector-borne protozoan miroparasites

Answer 8

Trypanosoma cruzi - Chagas disease - by kissing bugs, blood transfusion, mother to fetus
Trypanosoma brucei - african sleeping sickness
Plasmodium spp - malaria

Question 9

Chagas disease:

acute
chronic

Answer 9

pseudocysts form and heart diease

longer, kidney disease and heart disease and necrosis

Question 10

macroparasites

Answer 10

chronic
recurring infections
high morbidity
low mortality because needs the host
usually injest through unsanitised water
lay eggs in host that are excreted
faecal-oral route

Question 11

homogeneity

Answer 11

freely mixing population

Question 12

Ro

Answer 12

basic reproduction number (not rate)

average number of new cases arising form 1 infectious case introduced to population of wholly susceptible individuals

Question 13

what does the Ro have to be for an epidemic to occur?

Answer 13

> 1

or would only ever be 1 infected because previous would recover and may die out if 1 doesn’t pass it on

Question 14

Ro equation:

p
c
D

Answer 14

probability that contact results in transmission

frequency of host contacts between infectious and susceptible

average time host is infectious

Question 15

effective contact rate

Answer 15

S to I

p x c

Question 16

Re

Answer 16

effective R
when proportion of population is not susceptible
Ro x fraction of susceptibles
reduces with less susceptible individuals so epidemics end if no new susceptibles

Question 17

how are susceptibles replenished?

Answer 17

birth
migration
mutation of pathogen

Question 18

incubation period

Answer 18

between infection and onset of disease (symptoms)

Question 19

latent period

Answer 19

infection to infectiousness

Question 20

point epidemic

Answer 20

no continual intro of infection - food poisoning

so no curve, it just stops

Question 21

continuous common source epidemic

Answer 21

more permanent source like cholera - water

Question 22

propagated progressive source epidemic

Answer 22

spread between hosts

Question 23

index case

Answer 23

1st individual who brings disease

Question 24

what is Re for an endemic?

Answer 24

remains 1

Question 25

CCS

Answer 25

critical community size

min host population needed for pathogen to persist

Question 26

reservoir host vs carrier

Answer 26

carrier is individual from the reservoir host population

Question 27

mean burden

Answer 27

no. worms per host

Question 28

whipworm

Answer 28

inhibits growth and cognitive processes, lower IQ

Question 29

aims of intervention

Answer 29

control - maintain parasite population at acceptable level

elimination - within population, 0 incidence, local eradication

eradication - zero incidence worldwide

extinction - no longer in nature or lab

Question 30

herd immunity

Answer 30

right amount of population immune/vaccinated

Question 31

Ro = 1 + L/A

Answer 31

L = life expectancy
A = age when 1st infected

Question 32

Wakefield

Answer 32

MMR vaccine = autism
caused less vaccines and more measles cases
but paper was false

Question 33

ring vaccination

Answer 33

not just contacts but everyone within radius

Question 34

tracing (vaccines)

Answer 34

focus on contact and potential cases

1st and 2nd contacts

Question 35

anthroponetic

Answer 35

human to anthropod to human

e.g. malaria

Question 36

vectorial capacity (C)

Answer 36

average no. of potentially infective bites that will be delivered by all vectors feeding on single host in 1 day (units per day)

Question 37

vectorial capacity (C) equation

Answer 37

V - number of vectors
N - number of hosts
a^2 - vector biting rate per day
h^2 - host choice, proportion of meals on host
p - daily vector survival rate
n - extrinsic incubation period (EIP)

Question 38

EIP

Answer 38

latent period of agent inside vector - time after enters vector when can’t transmit yet

Question 39

how much has the temperature been rising each decade since 1970s?

Answer 39

0.2 degrees

greatest change in the northern hemisphere

Question 40

ARGO project

Answer 40

measure sea temp changes

Question 41

what diseases does climate change affect?

why?

Answer 41

mostly vector and water-borne

host env. won’t change with climate but there might be environmental stages of parasite or vector population that will be affected by climate

climate may change values in vectorial capacity equation

Question 42

dengue

Answer 42

virus
mosquito-borne
tropical
peak in southern oscillation causes peak in epidemics

Question 43

how did climate change affect BTV?

Answer 43

bluetongue virus
caused to travel geographically - midges are vectors
overwintering - survive over winter or persist in host over winter

Question 44

MHC

Answer 44

major histocompatibility complex
class 1 diversity
don't recognise cancer cells as foreign