A Methodology for Classifying Root Causes of Outbreaks of Legionnaires' Disease: Deficiencies in Environmental Control and Water Management.

We piloted a methodology for collecting and interpreting root cause-or environmental deficiency (ED)-information from Legionnaires' disease (LD) outbreak investigation reports. The methodology included a classification framework to assess common failures observed in the implementation of water management programs (WMPs). We reviewed reports from fourteen CDC-led investigations between 1 January 2015 and 21 June 2019 to identify EDs associated with outbreaks of LD. We developed an abstraction guide to standardize data collection from outbreak reports and define relevant parameters. We categorized each ED according to three criteria: ED type, WMP-deficiency type, and source of deficiency. We calculated the prevalence of EDs among facilities and explored differences between facilities with and without WMPs. A majority of EDs identified (81%) were classified as process failures. Facilities with WMPs (n = 8) had lower prevalence of EDs attributed to plumbed devices (9.1%) and infrastructure design (0%) than facilities without WMPs (n = 6; 33.3% and 24.2%, respectively). About three quarters (72%) of LD cases and 81% of the fatalities in our sample originated at facilities without a WMP. This report highlights the importance of WMPs in preventing and mitigating outbreaks of LD. Building water system process management is a primary obstacle toward limiting the root causes of LD outbreaks. Greater emphasis on the documentation, verification, validation, and continuous program review steps will be important in maximizing the effectiveness of WMPs.

A waterborne outbreak of gastroenteritis with multiple etiologies among resort island visitors and residents: Ohio, 2004.

BACKGROUND: The implementation of treated municipal water systems in the 20th century led to a dramatic decrease in waterborne disease in the United States. However, communities with deficient water systems still experience waterborne outbreaks. In August 2004, we investigated an outbreak of gastroenteritis on South Bass Island, Ohio, an island of 900 residents that is visited by >500,000 persons each year. METHODS: To identify the source of illness, we conducted a case-control study and an environmental investigation. A case was defined as diarrhea in a person who traveled to the island during the period from May 1 through 30 September 2004 and became ill within 2 weeks after the visit. Healthy travel companions served as matched control subjects. We also performed an environmental assessment and extensive testing of island water sources. RESULTS: Among the 1450 persons reporting illness, Campylobacter jejuni, norovirus, Giardia intestinalis, and Salmonella enterica serotype Typhimurium were identified in 16, 9, 3, and 1 persons, respectively. We interviewed 100 case patients and 117 matched control subjects. Case patients were more likely to drink water on the island than control subjects (68% vs. 35%; matched odds ratio, 4.3; 95% confidence interval, 2.2-9.3). Sampling of ground water wells indicated contamination with multiple fecal microbes, including Escherichia coli, C. jejuni, Salmonella species, and Giardia species. Irregularities in sewage disposal practices that could have contaminated the underground aquifer were noted. CONCLUSIONS: The combined epidemiological and environmental investigation indicated that sewage-contaminated ground water was the likely source of this large outbreak. Long-term changes to the island's water supply and sewage management infrastructure are needed.

A waterborne outbreak of Norwalk-like virus among snowmobilers-Wyoming, 2001.

In February 2001, episodes of acute gastroenteritis were reported to the Wyoming Department of Health from persons who had recently vacationed at a snowmobile lodge in Wyoming. A retrospective cohort study found a significant association between water consumption and illness, and testing identified Norwalk-like virus (NLV) in 8 of 13 stool samples and 1 well. Nucleotide sequences from the positive well-water specimen and 6 of the positive stool samples were identical. This multistrain NLV outbreak investigation illustrates the importance of NLV as a cause of waterborne illness and should encourage monitoring for NLVs in drinking water.

Outbreaks of Escherichia coli O157 infections at multiple county agricultural fairs: a hazard of mixing cattle, concession stands and children.

Escherichia coli O157 infections cause an estimated 60 deaths and 73 000 illnesses annually in the United States. A marked summer peak in incidence is largely unexplained. We investigated an outbreak of E. coli O157 infections at an agricultural fair in Ohio and implicated consumption of beverages made with fairground water and sold by a geographically localized group of vendors who were all on the same branch of the fairground water distribution system. To examine county fair attendance as a risk factor for infection, we conducted two further epidemiological studies. In the first, we enhanced surveillance for E. coli O157 infections in 15 Northeast Ohio counties during the 2000 agricultural fair season and showed increased risk of E. coli O157 infection among fair attendees. In the second study, we examined Ohio Public Health Laboratory Information Service (PHLIS) data for 1999 using a time-varying covariate proportional hazards model and demonstrated an association between agricultural fairs and E. coli O157 infections, by county. Agricultural fair attendance is a risk factor for E. coli O157 infection in the United States and may contribute to the summer peak in incidence. Measures are needed to reduce transmission of enteric pathogens at agricultural fairs.