Edwin E. Geldreich

A Waterborne Outbreak in Missouri of Escherichia coli O157:H7 Associated with Bloody Diarrhea and Death

OBJECTIVE To describe and determine the source of a large outbreak of Escherichia coli O157:H7 (ECO157) infections in Missouri. DESIGN A case-control study and a household survey. SETTING A small city in a rural Missouri township that had an unchlorinated water supply. PATIENTS Case patients were residents of or visitors to Burdine Township with bloody diarrhea or diarrhea and abdominal cramps occurring between 15 December 1989 and 20 January 1990. MEASUREMENTS Escherichia coli O157 was isolated from 21 stool specimens. All isolates were resistant to sulfisoxazole, tetracycline, and streptomycin; produced Shiga-like toxins I and II; and had one 60-megadalton plasmid. RESULTS Among the 243 case patients, 86 had bloody stools, 32 were hospitalized, 4 died, and 2 had the hemolytic uremic syndrome. In the case-control study, no food was associated with illness, but ill persons had drunk more municipal water than had controls (P = 0.04). The survey showed that, during the peak of the outbreak, bloody diarrhea was 18.2 times more likely to occur in persons living inside the city and using municipal water than in persons living outside the city and using private well water (P = 0.001). Shortly before the peak of the outbreak, 45 water meters were replaced, and two water mains ruptured. The number of new cases declined rapidly after residents were ordered to boil water and after chlorination of the water supply. CONCLUSIONS This was the largest outbreak of ECO157 infections, the first due to a multiply resistant organism, and the first shown to be transmitted by water. System-wide chlorination as well as hyperchlorination during repairs might have prevented this outbreak. Both bloody and nonbloody diarrhea may be common manifestations of this infection, which is probably underdiagnosed because of the failure of routine stool cultures to identify the organism. Cities with deteriorating water systems using untreated water risk widespread illness from contaminated drinking water.

Pathogenic agents in freshwater resources

Numerous pathogenic agents have been found in freshwaters used as sources for water supplies, recreational bathing and irrigation. These agents include bacterial pathogens, enteric viruses, several protozoans and parasitic worms more common to tropical waters. Although infected humans are a major source of pathogens, farm animals (cattle, sheep, pigs), animal pets (dogs, cats) and wildlife serve as significant reservoirs and should not be ignored. The range of infected individuals within a given warm-blooded animal group (humans included) may range from 1 to 25%. Survival times for pathogens in the water environment may range from a few days to as much as a year (Ascaris, Taenia eggs), with infective dose levels varying from one viable cell for several primary pathogenic agents to many thousands of cells for a given opportunistic pathogen. As pathogen detection in water is complex and not readily incorporated into routine monitoring, a surrogate is necessary. In general, indicators of faecal contamination provide a positive correlation with intestinal pathogen occurrences only when appropriate sample volumes are examined by sensitive methodology. Pathways by which pathogens reach susceptible water users include ingestion of contaminated water, body contact with polluted recreational waters and consumption of salad crops irrigated by polluted freshwaters. Major contributors to the spread of various water-borne pathogens are sewage, polluted surface waters and stormwater runoff. All of these contributions are intensified during periods of major floods. Several water-borne case histories are cited as examples of breakdowns in public health protection related to water supply, recreational waters and the consumption of contaminated salad crops. In the long term, water resource management must focus on pollution prevention from point sources of waste discharges and the spread of pathogens in watershed stormwater runoff.

Buffalo lake recreational water quality: a study in bacteriological data interpretation

Abstract Limited water resources in semi-arid regions can create a heavy public demand to use available water storage lakes for multiple use recreational purposes. Since bacteriological measurements of recreational water quality must be based on the detection of fecal contamination by all warm-blooded animals, this paper offers a rationale for the fecal coliform concept with respect to: sanitary significance, density relationships with fecal streptococci, and illustrates a bacteriological approach to a study of water quality in Buffalo Lake. Buffalo Lake, 30 miles (48 km) southwest of Amarillo, Texas, is part of a national wildlife refuge with authorized recreational uses in specified zoned areas to include swimming, water skiing, fishing, boating, and camping. Source water is derived from a drainage basin receiving only 15 in. (38.1 cm) of rainfall per year and supporting a human population of approximately 15,000 persons and a cattle feedlot population of approximately 180,000 animals. During the prevailing long dry weather periods the natural bathing water quality in the lake is excellent, as illustrated during a 1-week period (June 1968) when the fecal coliform median value from all 48 samples collected at six locations was 7 organisms per 100 ml. Stormwater runoff produced by infrequent heavy thunder-showers results in a dramatic deterioration in water quality for feeder streams, and subsequently produces a bacteriological impact on Buffalo Lake water quality which may be seen in fecal coliform values far in excess of the 200 organisms per 100 ml limit recommended by the National Advisory Committee on Water Quality Criteria. Corrective measures are discussed to more adequately control the pollutional discharges from domestic sewage and cattle feedlot drainage that reaches the lake, in addition to restrictions on bathing and water skiing when inflow from source waters temporarily reaches more than 450 acre-ft (5.6 × 105 m3) as a result of stormwater runoff; restrictions on horsepower limit and total number of motorboats, plus continuous maintenance and enforcement of a buffer zone between the wildlife refuge area and those areas of the lake designated for swimming, wading, and skiing.

Microbiological Quality of Source Waters for Water Supply

Protection of drinking water from contamination by human or other animal excrement in sewage, food processing wastes, and stormwater runoff is of paramount importance to everyone. Public health concerns must also include consideration of the availability of a continuous supply since water is essential to sustain life, with a prime consideration given to the production of water that is free of pathogenic agents and significant levels of toxic chemicals and is aesthetically pleasing in taste and appearance. More often than not, these basic requirements involve protection of water sources, conservation of water resources, and treatment to varying degrees to achieve the desired objective— a safe, continuous supply of drinking water.

Drinking water microbiology--new directions toward water quality enhancement.

Drinking water microbiology has emerged from decades of relative complacency to recognize there can be major concerns with potable water quality. Many of these issues are a result of an explosion of information on new waterborne agents, treatment problems with raw-source water qualities, biofilm development in some distribution systems and specialized requirements in water quality unique to hospitals and industries. Protozoan cyst survival after some disinfection practices involving surface water impoundments and virus occurrence in poorly protected groundwaters have provided reasons for expanding minimum treatment of surface waters and for requiring disinfection of all groundwaters unless there is a demonstrative data base to support exceptions in treatment requirements. Official monitoring of small water supplies must be increased on a monthly basis and a rapid alert established to inform water plant operators of unsatisfactory water qualities. As an option, application of operational tests to analyse water quality in terms of chlorine residual, turbidity, total coliforms and heterotrophic bacterial counts in small water plant operations should be encouraged. This would provide the operator at remote locations with the opportunity to utilize the information to make necessary treatment adjustments or corrections in water distribution deficiencies promptly and be a supplement to the official regional monitoring program. Application of drinking water alternative sources (bottled water and water from point-of-use treatment devices) should be viewed by the health authorities as only a temporary solution, not as a permanent fix for a public water supply known to present some established health risk to consumers. The public must also recognize that bottled water is not frequently monitored by health laboratories for acceptable quality and the use of home treatment devices places the responsibility of proper maintenance on the user. Microbial quality improvements in drinking water to hospitals and food industries can frequently be achieved through a routine, systematic flushing program for building plumbing networks and associated attachment devices. In other situations, use of booster disinfection or point-of-use devices may provide the important special water quality requirements for certain industrial applications. In any event, these supplemental treatment measures will require careful in-plant monitoring and maintenance to prevent reversals in water quality enhancement.

Home Treatment Devices and Water Quality

Drinking water quality is not uniform in its characteristics. While it may meet current government regulations for a safe supply, there can be pronounced differences in hardness, taste, odor, and other properties. Furthermore, there is growing evidence that groundwater quality in some small systems may have undesirable microbial, organic, inorganic, or radionuclide contaminants related to the source water characteristics of the supply. Periodic spills of a variety of pollutants into surface waters may also challenge the effectiveness of existing treatment processes in some public water supplies.

Bacteriological Changes Associated with Granular Activated Carbon in a Pilot Water Treatment Plant

Bacteriological analysis were performed on collected water samples from a conventional water treatment pilot plant in Cincinnati, Ohio in which granular activated carbon (GAC) has been used as the final process to assess the impact of GAC on the bacteriological quality and incidence of antibiotic resistant bacteria in water produced. Heterotrophic bacterial counts (HPC) at 20 °C was stabilized at 102 to 194 cfu mL-1 and did not markedly differ at different water treatment processes. On the other hand, slight reduction in HPC was observed for the effluent produced from sand filter and GAC contactors. Effluents produced from both the sand filter and GAC contactors showed 2 log reduction in coliforms count. Fecal coliform showed the same rate of reduction as a result of sand filtration, while it reached undetectable numbers in the effluent of GAC contactors. Subculturing the isolated strains in tryptic soy broth revealed that 61.3, 61.5, 12.6 and 8.5% of HPC at 28 °C, total coliforms and fecal coliform, respectively were non-culturable. In this case, R2A or R3A broth was used as subculturing media. The incidence of coliform resistant strains among isolates varied significantly according to the source of water samples. Multiple antibiotic resistance (MAR) was not always high in the same samples in which the overall resistance was high. The species composition varied considerably in different water samples. Selection for bacteria exhibiting resistance to antibiotic or antibiotics was observed under some experimental conditions using different doses of chlorine. The antibiotic resistance character was mostly transferable. As a conclusion, the use of GAC has no observable adverse effect on the bacteriological quality of the water produced from the pilot plant under investigation.

Searching for Rapid Methods in Environmental Bacteriology

With the evolution of treatment processes to control and improve the microbial quality of drinking water, wastewaters, and other infectious wastes, plant engineers have often requested operational monitoring methods that would provide a rapid characterization of the product water for determining treatment effectiveness. Furthermore, where downstream uses involve bathing or shellfish farming, application of a rapid test could provide a critical real time alert to potential public health problems in those designated areas. Unfortunately, monitoring programs today (Fig. 1) rely on standard test procedures that require 24 h or more sample processing time before results are available. As a consequence, this information is only a record of past treatment performance or of yesterday’s water quality conditions to which the public was exposed.