infectious disease

Question 1

two important characteristics used to classify infectious disease

Answer 1

reservoir

mode of transmission

Question 2

reservoir

Answer 2

natural habitat of organism

Question 3

mode of transmission

Answer 3

direct (human to human): sex, placenta, blood, skin, air(sneeze and coughs)
indirect (vector spread): water, food, animals, objects

Question 4

incubation period

Answer 4

The time between exposure to an infectious agent and the onset of symptoms or
signs of infection
it is dependent on:
Dose
-Route
-Rate of replication
-Host

Question 5

latent period

Answer 5

Time period from successful
infection until the development
of infectiousness

Question 6

infectious period

Answer 6

Period following infection when
infection can be transmitted to
another susceptible host

Question 7

serial interval

Answer 7

For diseases that are spread from person to person the time period between
successive generations

Question 8

secondary attack rate

Answer 8

The proportion of susceptibles who develop infection within the
incubation period after exposure to a primary case
secondary infections/ people exposed(in contact with primary case)

Question 9

pathogenicity

Answer 9

the ability of microbial agent to induce disease

illness rate= number with disease/ number with infection

Question 10

virulence

Answer 10

severity of disease after infection occurs

Question 11

immunogenicity

Answer 11

ability of organism to induce specific immunity

Question 12

Basic reproductive number

Answer 12

expected number of secondary cases from a single case introduced into a susceptible population
-if less than 1- disease will disappear
-if =1 disease will be endemic
if greater than 1 disease will be epidemic

Question 13

Net reproductive number

Answer 13

reproductive number at specified time

Question 14

reproductive number is a function of

Answer 14

infectiousness
contact pattern
duration of infectiousness
proportion immune in the population

Question 15

reproductive number (Ro) formula

Answer 15

probability of transmission in a contact between infected and susceptible individuals B
number of exposures of susceptible persons to infectious person per unit time-C
how long an infected person ins infectious -D

Question 16

herd immunity

Answer 16

1- (1/Ro)

Question 17

phase of epidemic

Answer 17

1- sporadic cases
2- clusters- imported cases and new local cases
3- main wave- widespread transmission
4- full epidemic- pressure on health care services
5- late epidemic- declining number of cases

Question 18

epidemiological triad

Answer 18

center vector (mode of transmission)
environment, host, agent

Question 19

host factors related to transmission

Answer 19

age
sex
occupation
 previous disease
immune status 
lifestyle 
host genome 
microbiome

Question 20

agent factors

Answer 20

virulence
genome
dose
sensitivity to antibiotics

Question 21

environment

Answer 21

temperature
humidity
crowding
pollution

Question 22

outbreak

Answer 22

An increase in the observed number of cases of a
disease or health problem compared to the expected
number (for a given place or among a specific group
of people over a particular time period)

Question 23

objectives in controlling outbreak

Answer 23

minimise number of primary cases (identify and control)
minimise number of secondary cases(identify and take action to control spread)
prevent further episodes(identify and eliminate hazards)

Question 24

steps for an outbreak investigation

Answer 24

verify diagnosis
establish existence of outbreak
identify and count cases
describe the epidemiology 
formulate and test hypo
assess response capacity and address gaps in resources
set up control measures 
communicate findings 
intensify surveillance