Table 1.
Characteristics of Legionnaires' disease cases and source-finding results in the epidemic group (weeks 32–38 in 2010) compared to domestic cases in 2008–2011 (excluding weeks 32–38 in 2010). [Source: National Infectious Diseases Surveillance database (Osiris)]
| Epidemic group* | Non-epidemic group* | P value | |||
|---|---|---|---|---|---|
| Patients' characteristics | N = 179 | (100%) | N = 650 | (100%) | |
| Male gender | 124 | (69·1%) | 463 | (71·2%) | 0·61 |
| Age >62 years (=median age) | 92 | (51·4%) | 311 | (47·8%) | 0·87 |
| Underlying disease† | 63 | (36·2%) | 253 | (39·8%) | 0·39 |
| Smoking‡ | 106 | (60·9%) | 347 | (54·6%) | 0·14 |
| Hospital admission | 177 | (98·9%) | 628 | (96·7%) | 0·19 |
| Death | 6 | (3·4%) | 43 | (6·6%) | 0·16 |
| Setting | |||||
| Community acquired | 157 | (87·7%) | 573 | (88·2%) | 0·87 |
| Nosocomial/healthcare setting | 5 | (2·8%) | 19 | (2·9%) | 0·93 |
| Domestic travel | 17 | (9·5%) | 53 | (8·2%) | 0·57 |
| Unknown | 0 | — | 4 | (0·6%) | 0·58 |
| Diagnostic methods | |||||
| Culture confirmed | 36 | (20·1%) | 140 | (21·5%) | 0·68 |
| Urine antigen test | 158 | (88·3%) | 560 | (86·2%) | 0·46 |
| Serology | 5 | (2·8%) | 58 | (8·9%) | <0·01 |
| Polymerase chain reaction | 26 | (14·5%) | 74 | (11·3%) | 0·25 |
| Patient isolates§ | N = 32 | (100%) | N = 132 | (100%) | — |
| L. pneumophila sg 1 | 29 | (90·6%) | 121 | (91·6%) | 0·74 |
| L. pneumophila sg 2–14 | 2 | (6·3%) | 7 | (5·3%) | 0·69 |
| Most frequent sequence types | |||||
| ST47 | 13 | (40·6%) | 49 | (37·1%) | 0·71 |
| ST62 | 2 | (6·3%) | 14 | (10·6%) | 0·46 |
| ST46 | 3 | (9·4%) | 8 | (6·1%) | 0·45 |
| ST45 | 3 | (9·4%) | 5 | (3·8%) | 0·19 |
| Non-L. pneumophila | 1 | (3·1%) | 4 | (3·0%) | 1·0 |
| Source finding | |||||
| Case mobility (range) | |||||
| Travel outside MHS region | 43 | (25·4%) | 159 | (26·0%) | 0·88 |
| Travel outside place of residence | 104 | (61·5%) | 327 | (53·5%) | 0·06 |
| Range unknown | 10 | (5·6%) | 39 | (6·0%) | 0·84 |
| Clustered cases | 6 | (3·4%) | 28 | (4·3%) | 0·57 |
| Cases with environmental sampling | 47 | (26·3%) | 142 | (21·8%) | 0·21 |
| Cases with positive sampling | 15 | (31·9%) | 66 | (46·5%) | 0·08 |
MHS, Municipal Health Service.
*
Epidemic group: domestic cases with onset disease in weeks 32–38 (2010). Non-epidemic group: domestic cases with onset of disease in 2008, 2009, 2010 (excluding weeks 32–38) and 2011.
†
Underlying disease was unknown in 2·8% and 2·2% of cases, respectively.
‡
Smoking was unknown for 2·8% and 2·0% of cases, respectively.
§
Source: Database National Reference Laboratory for Legionella in Haarlem, The Netherlands.