infectious disease Flashcards

1
Q

two important characteristics used to classify infectious disease

A

reservoir

mode of transmission

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2
Q

reservoir

A

natural habitat of organism

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3
Q

mode of transmission

A

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

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4
Q

incubation period

A
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
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5
Q

latent period

A

Time period from successful
infection until the development
of infectiousness

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6
Q

infectious period

A

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

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7
Q

serial interval

A

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

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8
Q

secondary attack rate

A

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)

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9
Q

pathogenicity

A

the ability of microbial agent to induce disease

illness rate= number with disease/ number with infection

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10
Q

virulence

A

severity of disease after infection occurs

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11
Q

immunogenicity

A

ability of organism to induce specific immunity

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12
Q

Basic reproductive number

A

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

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13
Q

Net reproductive number

A

reproductive number at specified time

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14
Q

reproductive number is a function of

A

infectiousness
contact pattern
duration of infectiousness
proportion immune in the population

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15
Q

reproductive number (Ro) formula

A

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

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16
Q

herd immunity

A

1- (1/Ro)

17
Q

phase of epidemic

A

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

18
Q

epidemiological triad

A
center vector (mode of transmission)
environment, host, agent
19
Q

host factors related to transmission

A
age
sex
occupation
 previous disease
immune status 
lifestyle 
host genome 
microbiome
20
Q

agent factors

A

virulence
genome
dose
sensitivity to antibiotics

21
Q

environment

A

temperature
humidity
crowding
pollution

22
Q

outbreak

A

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)

23
Q

objectives in controlling outbreak

A

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)

24
Q

steps for an outbreak investigation

A
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