What are the steps in outbreak investigation?
Hospitals are seeing an increase of Salmonellosis cases in a certain county. Is this an outbreak?
Yes. An outbreak is an excess of cases in a geographic region.
One case of rabies is reported in a dog in St Kitts. Is this an outbreak?
Yes. Since St Kitts is a rabies free country (haha), only one case is needed to be considered an outbreak.
What are some variables in defining whether there is truly an outbreak?
What is the baseline for that disease?
Are we just testing more than before?
Was there a lab error?
Has there been an increase in population since the baseline was determined before?
On the state/regional level, surveillance programs, pathologists, doctors, and the public are usually the ones detecting an outbreak. How is an outbreak detected in a farm setting?
Unusual morbidity, mortality, production, or reproductive losses.
Give 2 MAIN reasons to investigate an outbreak
Identify the source
Prevent more outbreaks
When describing an outbreak, you have to establish a case definition. What factors are included in a case definition?
If 11 out of 59 people eating at a restaurant at a certain time contract Salmonella from the food, what is the exposed population?
The 59 people eating at the restaurant
Case identification for non-communicable diseases involves testing the entire exposed population to identify all potential cases. How is case identification performed for communicable diseases?
Investigate all contacts of the case
What is the case fatality rate (CFR)?
Number of deaths among those who have the disease during a time interval
Describing the clinical features of a disease to define a case definition includes what factors?
Pattern: attack rate and CFR
What can we use for a spatio-temporal disease description?
Epidemic curve graphs
Spot maps (location)
T/F: It is necessary to identify the responsible agent in order to perform a full outbreak investigation?
What are the possible hypotheses we can formulate to determine the cause of an outbreak?
Best approach for control of the agent
Most likely method of transmission
What are the 5 steps to describing an outbreak?
Establish a case definition
ID responsible agent (sometimes)