Definitive case – one or more of the following:
(1) isolation of a Legionella species on culture from a patient
(2) urine Legionella antigen > 10 aU/mL
(3) four-fold rise or fall in antibody titers against L. pneumophila serogroups 1, 3 or 6 in paired samples AND maximum titer >= 1:128
(4) positive PCR on a sample from the lower airways AND urine Legionella antigen > 5 and <= 10 aU/mL
(5) positive PCR on a sample from the lower airway AND antibody titers > 1:256 against L. pneumophila serogroups 1, 3 or 6
(6) antibody titers > 1:256 against L. pneumophila serogroups 1, 3 or 6 AND urine Legionella antigen > 5 and <= 10 aU/mL
Presumptive case – not definitive AND one or more of the following:
(1) urine Legionella antigen > 5 and <= 10 aU/mL
(2) positive PCR on a sample from the lower airway
(3) antibody titer > 1:256 against L. pneumophila serogroups 1, 3 or 6
(4) four-fold rise or fall in antibody titers against L. pneumophila serogroups 2, 4 or 5 in paired samples AND maximum titer >= 1:128
(5) four-fold rise or fall in antibody titers against L. micdadei or L. bozemanii in paired samples AND maximum titer >= 1:128
(6) findings compatible with legionellosis during an outbreak
(7) any other findings consistent with a possible case
A case not definite or possible was classified as unlikely.
