1.5 An example: Research in action

During 1988/1989, an unusually high number of cases of the Legionella longbeachae infection were observed in South Australia. Why? What could be done to prevent more instances?

The researchers wanted to identify the source of the infection. They noticed that many of those infected were regular gardeners who had handled potting mix recently. So the researchers wondered:

… if L. longbeachae infection was associated with handling of commercial potting mix.

O’Connor et al. (2007), p. 35

They designed a study, then gathered data (using a survey) from 100 people: 25 people with the L. longbeachae infection, and 75 similar (‘matched’) people without the infection

The researchers described and summarised their data, analysed the data, and then reached an evidence-based conclusion: the potting mix was partially responsible for the increase in infection numbers, but other factors were also involved.

The researchers then communicated their recommendations to reduce the future risks of people contracting the infection:

Raising people’s awareness of a possible health risk when using potting mix should continue in order to protect against L. longbeachae infection.

O’Connor et al. (2007), p. 39


O’Connor BA, Carman J, Eckert K, Tucker G, Givney R, Cameron S. Does using potting mix make you sick? Results from a Legionella longbeachae case-control study in South Australia. Epidemiology and Infection. 2007;135:34–9.