Legionnaires' disease is a severe type of pneumonia that is under-diagnosed in New Zealand. Special tests are required to make a diagnosis of legionnaires' disease, but there are no clear guidelines about which patients to test. An enhanced testing system for legionnaires' disease was developed in Canterbury and has been used there since 2010. The system involves targeted use of the current best test for legionnaires' disease: PCR (polymerase chain reaction), which detects bacterial DNA. This approach has uncovered many cases of legionnaires' disease that would have otherwise gone undetected. This study will roll out this same testing strategy across New Zealand for one year in order to measure the national burden of legionnaires' disease; to improve patient treatment; to identify cost-effective ways to test for legionnaires' disease in the future; and to create better guidelines for the treatment of pneumonia.