Chatu Yapa, Masters in Applied Epidemiology trainee, Health Protection NSW
The flu season has hit states and territories throughout Australia exceptionally hard this year, with more than 42,300 laboratory confirmed cases recorded at the end of August. This compares to approximately 14,000 lab-confirmed cases at the same time last year.
These kinds of numbers are able to be determined at a local and state level because of the application of a standardized case definition, which allows public health professionals to classify and count cases consistently across reporting jurisdictions.
Imagine that you are a public health officer investigating an influenza outbreak in an aged care facility (ACF X) in your local health district. The experienced nurse in charge, in anticipation of your visit, has attempted to help in the investigation by developing some case definitions and creating a line list of cases as shown in the table below.