Foodborne disease and outbreak investigation Flashcards
How many deaths (roughly) are caused by year from contaminated food or water?
2 million
What percentage of foodborne illness is caused by unknown pathogens?
80% (in US) Hence difficult to set up risk-based management
What are the four main agents identified in food borne illness of a known pathogen?
Salmonella, Campylobacter, Viruses and Bacterial Toxins
What is the definition of an outbreak?
Cases clustered in time and space at a higher level than expected
What is the definition of an epidemic?
Occurrence of more cases of disease than expected in a given area or among a specific group of people over a particular period of time
What are the steps in investigating foodborne disease?
Detect a possible outbreak Find cases in outbreak Hypothesis through interviews Test hypothesis via analytic studies and laboratory testing Solve point of contamination and original source of outbreak vehicle Control outbreak through recalls, facility improvements and industry collaboration Decide when an outbreak is over
What are the seven steps during a foodborne outbreak investigation according to WHO?
Preliminary assessment of situation Communication Descriptive epidemiology Food and environmental investigations Analysis and interpretation Control measures Further studies
What are the three objectives in controlling an outbreak?
1) Reduce the number of primary cases (involves recognition of outbreak, identification and control of the source) 2) Reduce the number of secondary cases (by identifying cases and taking action to prevent subsequent spread) 3) Prevent further episodes by identifying continuing hazards and eliminating/minimising their risk
What kind of epidemic trend does this curve show?
Point source (1 incubation period)
What kind of trend does this epidemic curve show?
Intermittent common source
What kind of spread does this epidemic curve show?
Propagates (person to person)
What kind of spread does this graph indicate?
Continuous common source
What is the role of molecular typing techniques in foodbourne outbreak investigation?
Establishment of the primary source of bacterial contamination
Bacterial source tracking
What are the 3 molecular typing techniques commonly used in foodbourne outbreak investigation?
PCR
Sequencing
Restriction enzymes
How do you decide what time units you will use in your epidemic curve?
Units should be no more than 1/3rd of incubation period e.g. if incubation period is 3 days, unite should be no bigger than 1 day incremements
