TABLE 3.
Water quality indicators, by harmful algal bloom–associated waterborne disease outbreak — United States, 2009– 2010
| Outbreak (by state) | Water quality indicators* | |||||
|---|---|---|---|---|---|---|
|
| ||||||
| Cyanobacteria | Escherichia coli | Anatoxin-a (μg/L) | Cylindrospermopsin (μg/L) | Microcystin (μg/L) | Saxitoxin (μg/L) | |
| New York (Outbreak 1) | X | — | — | — | 112.5 | — |
| New York (Outbreak 2) | — | — | — | — | — | — |
| New York (Outbreak 3) | X† | >126 CFU/mL§ | — | — | — | — |
| Ohio (Outbreak 4) | — | — | 0.05–0.1 | ND | 4.6 | ND |
| Ohio (Outbreak 5) | — | — | — | — | >1,000.0 | — |
| Ohio¶ (Outbreak 6) | X** | — | ND | ND | 0.2 | 0.03 |
| Ohio¶ (Outbreak 7) | — | — | — | ND | 20.8 | ND |
| Ohio¶ (Outbreak 8) | — | — | 15.0 | 9.0 | >2000.0 | 0.09 |
| Ohio (Outbreak 9) | — | — | 0.2 | 0.3 | 0.3 | ND |
| Washington (Outbreak 10) | — | — | — | — | <6.0†† | — |
| Washington (Outbreak 11) | — | — | — | — | — | — |
Abbreviations: ND = not detected (Water test results indicated that the toxin was not present in water samples or that the concentration was below the level of detection); CFU = colony forming unit.
Water quality indicators reported to the National Outbreak Reporting System or the Harmful Algal Bloom-Related Illness Surveillance System: identification of one or more cyanobacterial genera in lake water sample, Escherichia coli, and maximum cyanotoxin concentrations (i.e., within 1 day of outbreak exposure period).
Both exposures occurred on a single day. Microcystis was identified by microscopy 3 days after the date of the exposure.
E. coli measurements exceeded 126 CFU/100 mL before, during, and after the exposure period. Reported levels were 328 CFU/100 mL (4 days prior), 488 CFU/100 mL (2 days prior), 152 CFU/100 mL (day of exposure), 248 CFU/100 mL (1 day after), and 222 CFU/100 mL (3 days after).
Exposure occurred at a lake that was a water source for a public water system. Cyanotoxin analysis of finished water samples indicated that algal toxins were not present or that concentrations were below the limit of detection.
Mixed toxigenic cyanobacteria bloom that included abundant cyanobacteria in succession: initially Anabaena spp., then Cylindrospermopsis raciborskii, Aphanizomenon spp., and Planktolyngbya limnetica. Four days after the date of last exposure, microcystin was not detected, saxitoxin was measured at 0.05 μg/L, and anatoxin-a was measured at 0.05–0.1 μg/L.
Microcystin measurements were >6 μg/L during the week before the outbreak.