Outbreaks Flashcards
Define an outbreak (3 possible definitions)
2 or more cases of an infection linked by time, place or person
An increase in cases of a disease over and above the normal background rate
Any case of an infection that doesn’t normally occur in a setting and carries a high public health risk
Name the key stages of managing an outbreak
- Confirm the diagnosis
- Define a case definition and conduct case finding
- Collect case information
- Analyse data
- Interpret data and manage risk
- Test hypothesis
- Draw conclusions
- Prepare written report
- Execute control and prevention measures
How can cases be confirmed?
Samples from the cases/food/environment
How can cases be defined?
By clinical features, by lab results, by epidemiology
Must be appropriate for the area you’re working in, precise and accurate
How are cases found?
GPs
Hospital data
Schools etc
What is the difference between a case control and a cohort study?
Case control - analyse the difference between case group and control group - must therefore know all cases
Cohort - take data from those affected by the disease - cannot compare
What might you ask in a case studies?
Demographics - age/sex/ethnicity Details of their illness Exposure details Details of any other known cases Burden of disease Recent activities
How should the data be analysed?
Epidemiologically -
TIME, PLACE, PERSON, EXPOSURE
What does interpreting the data involve?
Establishing whether the outbreak is point source, continuing or propagated
What does the risk assessment identify?
Who is at risk?
What is the severity of the disease?
Who might be part of an outbreak control team?
Health protection specialist Public health officer Doctors - usually GPs Microbiologist Communication leads School teachers/nurse Education representative Local council Environmental specialist if relevant
What is a point source outbreak - give an example of a disease that could cause a point source outbreak
Source infects cases at one particular location over a short period of time
Eg: Hepatitis A,
What is a continuing source outbreak and give an example
When all/most cases are infected by the same source but over a long period of time
Eg: GE
What is a propagated/case-to-case outbreak and give an example
Communicable through human transmitted - the causative agent is propagated within the population
Eg: TB, HIV, STIs,
What are the aims of outbreak investigation/management?
Minimise the number of primary cases
Minimise the number of secondary cases
Identify and eliminate sources of infection
Introduce measures to prevent future outbreaks
What features of outbreak data and information are essential?
Accuracy Consistency Freedom from bias Confidentiality Security Accessibility
What is the odds ratio?
Calculate the approximate relative risk of developing a disease
How is odds calculated?
Odds= risk of event A occuring / risk of event B occuring
How is odds ratio calculated?
Odds 1 / Odds 2
Odds 1= cases with exposure / cases without exposure
Odds 2 = controls with exposure / controls without exposure
In an outbreak of a disease transmitted faeco-orally (eg: food poisoning) name some features of the outbreak management
Identify causative microbiological agent Obtain stool samples Collect clinical details Exclude cases from work/school Provide hygiene advice Check food hygiene and safety standards Check infection control practices
In an airborne disease outbreak such as TB/influenza - name some features of the outbreak management
Test to confirm strain type/microbiological agent
Mass Immunisations
Chemoprophylaxis
Reinforce hygiene measures
In a blood-borne disease outbreak - name some features of outbreak management
Testing for viral cause
Look for a potential common source
Education advice
Enhanced surveillance??
How would you manage a blood exposure incident?
Wash the wound with soap and water
Test the source (eg: if came from a patients blood sample)
Give PEP if HIV risk
Accelerated Hep B vaccination schedule
In a vector-borne outbreak what should you consider in outbreak management?
Reviewing travel advice
Testing to confirm diagnosis
Treat patient
Minimise vector transmission - insecticides, molliscides etc.
If not endemic - notify authorities (eg: malaria in the UK)
