Table 1.

Basis of case classification and infecting organism

Case classification and basis for classification	Legionella species	Number of cases	Serological titres (first sample/second sample)
Legionnaires’ Disease – Confirmed
Sputum culture positive	L. pneumophila sg1	2	Not collected
Urinary antigen positive; two elevated convalescent titres	L. pneumophila sg1	1	512/1024
Fourfold rise in serological titres	L. longbeachae sg1	1	1024/4096
Legionnaires’ Disease – Probable
Two elevated serological titres	L. pneumophila sg5	1	512/512
Single elevated serological titre	L. longbeachae sg1	1	2048/not collected
Pontiac Fever – Probable
Two elevated serological titres	L. longbeachae sg1	3	512/512
			512/1024
			512/1024
	L. longbeachae sg2	1	512/1024
	L. pneumophila sg1	1	512/512
	L. sainthelensi	1	512/512
Single elevated serological titre*	L. sainthelensi	1	512
Total cases		13

sg, serogroup; *titre below cut-off value on second sample.