Infectious Disease Epidemiology

Question 1

What is the importance of infectious disease epidemiology?

Answer 1

Assessing changes in the pattern of infectious disease.

Discovery of new infections

Creating links between infection and chronic disease

Question 2

What is an infectious disease?

Answer 2

Due to infectious agents or toxic products which can be transferred from one living thing to another or from the environment.

Question 3

What is an infection?

Answer 3

Entry and development or multiplication of an infectious agent in the body.

Question 4

What are the levels of infection?

Answer 4

Colonization

Subclinical

Latent infection

Question 5

What is a contagious disease?

Answer 5

Transmitted through contact between individuals

Question 5

What is a host?

Answer 5

A living thing that affords the lodgement of an infectious agent under natural conditions

Question 6

What is a vector of infection?

Answer 6

Any living carrier that transports an infectious agent from affected to susceptible individual (food or surrounding)

Question 7

What is a reservior?

Answer 7

Anything in which an infectious agent normally lives and multiples on which it depends primarily on survival and where it reproduces itself in such a manner that it can be transmitted to a host.

Question 8

What is incidence?

Answer 8

Number of new cases in a given time period expressed as percent infected per year (cumulative incidence) or number per person time of observation (incidence density)

Question 9

What is prevalence?

Answer 9

Number of cases at a given time expressed as a percent at a given time

Question 10

What is an endemic?

Answer 10

Constant presence of a disease or infectious agent within a given geographic area or population group, but at a relatively low frequency.

Question 11

What is an epidemic?

Answer 11

The unusual occurrence in a community of disease, specific health related behaviour, or other health related events clearly in excess of expected occurrence

Question 12

What is a pandemic?

Answer 12

Epidemic becomes more widespread

Question 13

What is zoonosis?

Answer 13

An infection that is transmissible, under natural conditions, directly from vertebrate animals to man

Question 14

What does sporadic mean?

Answer 14

Cases of sporadic infection occur irregularly, haphazardly from time to time, and generally infrequently.

Question 15

What kind of CJD exists?

Answer 15

Sporadic

Genetic

Acquired

Question 16

What was BSE?

Answer 16

Mad Cow disease

Question 17

Where did BSE begin?

Answer 17

A single strain of scrapie (sheep disease).

This is because cows were fed sheep brain?

Question 18

How was BSE stopped?

Answer 18

Feed ban introduced in 1988

Question 19

What is CJD?

Answer 19

Creutzfeldt-Jakob Disease

Question 20

What is Creutzfeldt-Jakob Disease?

Answer 20

Rare and fatal neurodegenerative disease

Question 21

What is the CJD incubation period?

Answer 21

Very long

Question 22

What test is preformed to test for CJD?

Answer 22

No test to identify asymptomatic infection

Question 23

What is a prion?

Answer 23

The disease of structurally abnormal proteins.

Question 24

How is CJD transmitted?

Answer 24

By blood, blood products and surgery.

Question 25

What is the median onset age for sporadic CJD?

Answer 25

64 years (usually >55 years)

Question 26

What is the median onset age for variant CJD?

Answer 26

26 years (range 12-74 years)

Question 27

What is the median duration for sporadic CJD?

Answer 27

4 months

Question 28

What is the median duration for variant CJD?

Answer 28

14 months

Question 29

What are the symptoms of sporadic CJD?

Answer 29

Early loss of memory, cognition, myclonus, cerebellar ataxia

Question 30

What are the symptoms of variant CJD?

Answer 30

Early behavioural and psychiatric changes

Question 31

How common is sporadic CJD?

Answer 31

1 case per million worldwide

Question 32

How common is variant CJD?

Answer 32

176 cases by December 2011

Question 33

Which part of the body does sporadic CJD affect?

Answer 33

Affects brain and CNS

Question 34

Which part of the body does variant CJD affect?

Answer 34

Affects a wider range of tissues

Question 35

What is the current UK CJD Public Health action?

Answer 35

• Monitor prevalence
• Monitor risk management
• Enhanced surveillance

Question 36

What is passive surveillance?

Answer 36

• Routine information sources
• Automatic reporting

Question 37

What is active surveillance?

Answer 37

• Special effort to contact healthcare providers to collect data and confirm diagnoses
• Public health response may be needed

Question 38

What is enhanced surveillance?

Answer 38

Gathering additional collected for each cases

Question 39

What kind of additional information can be gathered during enhanced surveillance?

Answer 39

Clinical information

Capture of risk factor

Merging data from different sources

Merging results from microbiology characterisation to routine reports

Question 40

What is the purpose of surveillance?

Answer 40

Monitor slow changes

Detection of outbreaks and epidemics

Evidence base for policy and guidance information

Stimulates public health research

Providing information for modelling studies

Question 41

What is sentinel surveillance?

Answer 41

Sentinel surveillance is monitoring of rate of occurrence of specific diseases and conditions through a voluntary network of doctors, laboratories and public health departments with a view to assess the stability or change in health levels of a population.

Question 42

What needs to be controlled when using sentinel surveillance?

Answer 42

Sampling must be representative and nil return is needed.