Table 1.
Selected examples of Legionella spp. occurrence in potable water distribution and plumbing systems.
| Location | Organism | % Occurrence | Mean Density in Positive Samples | Refs. |
|---|---|---|---|---|
| Blacksburg-Christiansburg-VPI Water Authority (Virginia, USA; n = 29) | Legionella spp. | 69 | 187 gc/mL | [20] |
| L. pneumophila | 13.7 | 9.8 gc/mL | ||
| Vermamoeba vermiformis | 27.6 | 1.2 ×104 gc/mL | ||
| Acanthamoeba sp. | 13.7 | 2.2 gc/mL | ||
| Pinellas County, FL (USA; n = 15) | Legionella spp. | 100 | 100.8 gc/mL | [20] |
| L. pneumophila | 20 | 90.4 gc/mL | ||
| Vermamoeba vermiformis | 73.3 | 781.7 gc/mL | ||
| Acanthamoeba sp. | 6.7 | ND * | ||
| Catalonia (Spain) | Legionella spp. | 35 | 6.9 CFU/100 mL | [19] |
| Nara/Gifu/Aichi/Shizuoka (Japan) | Legionella sp. | 1.6 CFU/100 mL | [21] | |
| Amoeba | 2.4 MPN/100 mL | |||
| Ciliates | 1.1 MPN/100 mL | |||
| Flagellates | 2.8 MPN/100 mL | |||
| Pittsburg Psychiatric Hospital | Legionella sp. | 50%–90% | 117.5/swab | [22] |
| London (cooling tower foam) | L. pneumophila 1 | 105 cfu/mL | [16] | |
| Miyazaki, Japan (spa) | Legionella sp. | 1.5 × 107 cfu/L | [23] | |
| Shizuoka, Japan (outdoor thermal spring) | Legionella sp. | 5.7 × 105 cfu/L | ||
| Shizuoka, Japan (indoor thermal spring) | Legionella sp. | 8.8 × 105 cfu/L | ||
| Singapore | Legionella sp. | 15.6% (cooling towers); 12.4% (fountains) | No reported | [14] |
| Israel | Legionella spp. | 7.2–18.2 over 5 years | Not reported | [13] |
* ND = Not detected (but some gene copies detected in the biofilm).