TABLE 2.
Rank order (most to least common) of etiology, water system, water source, predominant illness, and deficiencies associated with 32 drinking water outbreaks and 431 outbreak-related cases — United States, 2011–2012
| Outbreaks (N = 32) | Cases (N = 431) | ||||||
|---|---|---|---|---|---|---|---|
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| Characteristic | Rank | Category | No. | (%) | Category | No. | (%) |
| Etiology | |||||||
| 1 | Bacteria, Legionella | 21 | (65.6) | Viruses | 138 | (32.0) | |
| 2 | Bacteria, non-Legionella | 3 | (9.4) | Bacteria, Legionella | 111 | (25.8) | |
| 3 | Parasites | 2 | (6.3) | Bacteria, non-Legionella | 90 | (20.9) | |
| 4 | Viruses | 2 | (6.3) | Parasites | 49 | (11.4) | |
| 5 | Unknown | 2 | (6.3) | Chemical* | 26 | (6.0) | |
| 6 | Chemical* | 1 | (3.1) | Unknown | 10 | (2.3) | |
| 7 | Multiple† | 1 | (3.1) | Multiple† | 7 | (1.6) | |
| Water system § | |||||||
| 1 | Community | 25 | (78.1) | Noncommunity | 222 | (51.5) | |
| 2 | Noncommunity | 5 | (15.6) | Community | 184 | (42.7) | |
| 3 | Bottled | 2 | (6.3) | Bottled | 25 | (5.8) | |
| Water source | |||||||
| 1 | Surface water | 18 | (56.3) | Ground water | 261 | (60.6) | |
| 2 | Ground water | 11 | (34.4) | Surface water | 120 | (27.8) | |
| 3 | Mixed¶ | 2 | (6.3) | Unknown | 22 | (5.1) | |
| 4 | Unknown | 1 | (3.1) | Mixed¶ | 28 | (6.5) | |
| Predominant Illness ** | |||||||
| 1 | ARI | 21 | (65.6) | AGI | 308 | (71.5) | |
| 2 | AGI | 10 | (31.3) | ARI | 111 | (25.8) | |
| 3 | Other†† | 1 | (3.1) | Other†† | 12 | (2.8) | |
| Deficiency §§ | |||||||
| 1 | Legionella spp. in drinking water system¶¶ | 21 | (65.6) | Untreated ground water*** | 201 | (46.6) | |
| 2 | Untreated ground water*** | 4 | (12.5) | Legionella spp. in drinking water system¶¶ | 111 | (25.8) | |
| 3 | Premise plumbing system††† | 2 | (6.3) | Premise plumbing system | 33 | (7.7) | |
| 4 | Unknown/Insufficient information | 2 | (6.3) | Distribution system§§§ | 28 | (6.5) | |
| 5 | Distribution system§§§ | 1 | (3.1) | Point of use, bottled¶¶¶ | 22 | (5.1) | |
| 6 | Multiple**** | 1 | (3.1) | Multiple**** | 21 | (4.9) | |
| 7 | Point of use, bottled¶¶¶ | 1 | (3.1) | Unknown/Insufficient information | 15 | (3.5) | |
Abbreviations: AGI = acute gastrointestinal illness; ARI = acute respiratory illness.
Propylene glycol detected in drinking water after cross-connection with HVAC water system.
One outbreak had multiple etiologic agent types: Campylobacter spp. (i.e., non-Legionella bacterium) and Giardia intestinalis (i.e., parasite).
Community and noncommunity water systems are public water systems that have =15 service connections or serve an average of =25 residents for =60 days a year. Community water systems serve year-round residents of a community, subdivision, or mobile home park. Noncommunity water systems serve an institution, industry, camp, park, hotel, or business.
Includes outbreaks with mixed water sources (i.e., ground water and surface water). Two giardiasis outbreaks were associated with mixed source community water systems.
The category of illness reported by =50% of ill respondents; all legionellosis outbreaks were categorized as ARI.
Outbreaks are assigned one or more deficiency classifications. (Source: Brunkard, JM, Ailes E, Roberts VA, et al. Surveillance for waterborne disease outbreaks associated with drinking water-United States, 2007–2008. MMWR Surveill Summ 2011;60:38–68).
Symptoms for one outbreak caused by Pantoea agglomerans bloodstream infection were categorized as “other.”
Deficiency 5A. Drinking water, contamination of water at points not under the jurisdiction of a water utility or at the point of use: Legionella spp. in water system, drinking water.
Deficiency 2. Drinking water, contamination of water at/in the water source, treatment facility, or distribution system: untreated ground water.
Deficiency 6. Drinking water, contamination of water at points not under the jurisdiction of a water utility or at the point of use: Plumbing system deficiency after the water meter or property line (e.g., cross-connection, backflow, or corrosion products).
Deficiency 4. Drinking water, contamination of water at/in the water source, treatment facility, or distribution system: Distribution system deficiency, including storage (e.g., cross-connection, backflow, contamination of water mains during construction or repair).
Deficiency 11C. Drinking water, contamination of water at points not under the jurisdiction of a water utility or at the point of use: Contamination at point of use, commercially bottled water.
Multiple deficiencies were assigned to one giardiasis outbreak which contributed 21 cases: deficiency 1, untreated surface water; and deficiency 2, untreated ground water.