Health Commissioner Releases E. coli Outbreak Report
Albany, March 31, 2000 – State Health Commissioner Antonia C. Novello, M.D., M.P.H. today released the final report detailing results of the New York State Department of Health's investigation into the 1999 E. coli 0157:H7 outbreak associated with attendance at the Washington County Fair. The findings indicate that the outbreak may have resulted from contamination of the Fair's Well 6 by a dormitory septic system on the fairgrounds, although manure runoff from the nearby Youth Cattle Barn cannot be ruled out as a possible contamination source.
The six–month investigation was conducted by scientists, engineers and technicians from the Health Department's Division of Epidemiology, Center for Environmental Health and Wadsworth Center. In addition, the Department received substantial and critical assistance from other government agencies including county health departments, the New York State Police and federal Centers for Disease Control and Prevention.
The Health Department's final report is not able to definitively endorse or reject any specific hypothesis regarding the source(s) of the bacteria that led to the outbreak or the mechanism(s) by which that bacteria was able to infect certain Fair attendees.
"The Department promised the Aldrich family and the parents of all the children who were infected with E. coli that we would do everything within our power to discover exactly what happened at the Fair, how it happened, and why, and then publicly report our findings," Dr. Novello said. "The lessons we have learned from this tragedy and the actions we are taking today will help to prevent future outbreaks. Our objective is to allow New Yorkers to enjoy family outings without worrying that the water they drink will make them sick.
While we will never recover the two lives lost to this event, we can use the experience to improve our oversight of agricultural fairgrounds. Assuring New Yorkers of safe drinking water is one of our highest priorities – and this summer fair attendees may rest assured that the Department of Health is at work to protect their safety and health," Dr. Novello said.
Three–year–old Rachel Aldrich died after being infected with the toxic E. coli O157:H7 strain at the Fair. A 79–year–old patient also died from complications of the infection. Hundreds of others, including Rachel's sister, Kaylea, became ill in the outbreak. Some of those individuals were infected with another type of bacteria, Campylobacter jejuni (Campylobacter), which also causes gastrointestinal illness and can be contracted by drinking contaminated water.
DOH identified 71 people who were hospitalized during the outbreak. Of these, 14 developed hemolytic uremic syndrome (HUS), a severe complication of E. coli O157:H7 infection that can lead to kidney failure. An investigation by epidemiologists–scientists who study the causes and transmission of disease–identified 781 persons with confirmed or suspected illness (persons who developed symptoms) related to this outbreak. Of these, 127 cases of E. coli and 45 cases of Campylobacter were confirmed by culture.
"Given the number of culture–confirmed and suspected cases, Washington County Fair illnesses are believed to represent the largest waterborne E. coli O157:H7 outbreak in United States history," Dr. Novello said.
As is explained in detail below, an environmental health investigation was unable to prove or disprove the initial hypothesis that water from Well 6 was contaminated by runoff from cattle manure. Studies did indicate, however, that the contamination may have originated from a septic system serving a 4–H dormitory on the fairgrounds close to Well 6.
Because it was impossible to replicate the exact environmental conditions present during the Fair at the time we conducted our study, neither theory can be ruled out. A dye test of the 4–H dormitory septic system showed a hydraulic connection––which is a flow of water between two points––between the dormitory septic system and Well 6 at the time of the study. A similar dye study of the manure storage area did not show a hydraulic connection between that storage area and Well 6 at the time of the study. However, that study was not performed immediately after a period of drought followed by substantial rains – the conditions that existed during the fair – making it difficult to establish the actual source of contamination.
Details of the Department's Investigation
The parallel investigations by DOH epidemiologic, environmental and laboratory staff involved more than 125 individuals who spent thousands of hours working on all phases of the outbreak response. Staff included laboratory scientists and technicians who processed and analyzed more than 220 human and environmental samples. Sanitary engineers traced the Fair's water and wastewater disposal systems and collected environmental samples. Public health workers interviewed hundreds of local residents and analyzed results of a telephone survey to help pinpoint the most likely source of the outbreak. Communicable disease experts assisted area health departments and hospitals with case findings. Following are some results of the investigation:
Division of Epidemiology
- Epidemiologists concluded that most individuals with culture–confirmed cases of E. coli or Campylobacter infection appear to have been exposed on August 28 or 29.
- A case–control study concluded that consumption of beverages sold by vendors supplied with water from Well 6 was a key risk factor for patients with culture–confirmed illness.
- Results of a telephone survey revealed that one or more persons from approximately 40 percent of Washington County households attended the Fair. Based on these survey findings, it is estimated that between 2,800 and 5,000 Washington County Fair attendees may have developed gastrointestinal illness.
Center for Environmental Health
- A dye study of the septic system for a nearby dormitory on the fairgrounds showed a hydraulic connection between the septic system and Well 6 at the time of the study (late September 1999). A dye study of the manure storage area did not show a hydraulic connection between that storage area and Well 6 at the time of the study.
- E. coli O157:H7 was found in samples from Well 6, which supplied unchlorinated water to some vendors, and water distribution pipes leading from Well 6. E. coli O157:H7 also was found in the septic system of the dormitory building. The discharge area (seepage pit) of that septic system is approximately 36 feet from Well 6.
- Environmental tests demonstrated a groundwater flow, at the time of the tests, from the septic system to Well 6. Tests have not demonstrated a flow from the manure storage area near the Youth Cattle Barn or the presence of E. coli O157:H7 in samples taken from that area. However, because exact environmental conditions (including drought followed by rain) present at the time of the Fair cannot be replicated and because manure was removed daily, it may never be known if manure–contaminated water percolated from the manure storage area to Well 6.
- The source of the E. coli O157:H7 in the dormitory septic system is unknown and tests have not identified Campylobacter in samples from the dormitory septic system or Well 6.
- Wadsworth Center received from 16 hospital and other private laboratories specimens from patients suspected of having outbreak–associated infections. From September 6 through October 22, 152 suspected E. coli O157:H7 and Campylobacter isolates cultured from stool and three primary stool specimens were analyzed. Eighty–eight percent of the isolates and 100 percent of the stools were positive for E. coli O157:H7. Wadsworth also received 36 outbreak–associated isolates for Campylobacter culture, of which 94 percent were positive.
- Given the clinical suspicion that patients were infected with E. coli O157: H7, the laboratory attempted to isolate the organism from Well 6 water, which had shown high numbers of coliform bacteria. E. coli O157: H7 was found in samples from Well 6 and its water distribution pipes.
- Methods that detect unique genetic elements of microorganisms also were used to identify the E. coli O157: H7 organism. A "molecular photocopying" technique called polymerize chain reaction (PCR) was employed. A total of 128 PCR tests were conducted on patient specimens and environmental samples.
- DNA fingerprints of E. coli 0157:H7 from the septic tank, Well 6 and distribution pipes leading from Well 6 were indistinguishable from the DNA fingerprints of E. coli 0157:H7 in many culture–confirmed patients.
State Health Department Actions:
The outbreak at the Washington County Fair demonstrates the need for closer oversight and regulation of events of this kind. On September 13, 1999, the State Health Commissioner issued an emergency order that prohibited the use of untreated water at six agricultural fairgrounds in the State and required them to assess their water supplies. On December 21, 1999, Dr. Novello extended the requirements of the initial order until October 1, 2000. On February 7, 2000, a seventh fairground was added to the original list. The Health Department has distributed guidelines to officials of the seven fairgrounds to assist them in preparing required engineering reports.
Officials of agricultural fairgrounds unaffected by the Commissioner's orders because they purchase water from approved public water systems also have been notified that a comprehensive assessment of the adequacy of each fairground's water distribution system should be completed and submitted to the Department for review.
Local health departments, likewise, have received policy guidance reinforcing and clarifying the requirements for water systems at facilities regulated by the Department. Health officials will carefully review all public water systems that hold disinfection waivers to ensure that the water sources are properly engineered and monitored and that these systems have a demonstrated history of good water quality.
Legislation giving the State Health Department explicit authority to regulate agricultural fairgrounds is being proposed. Dr. Novello has directed her staff to review existing statutes and regulations to determine whether other changes to regulation or law should be made.
"We will take whatever steps are necessary to ensure that a tragedy of this nature never happens again, and that New Yorkers can count on a clean, safe water supply."