6.5

Fecal/Vomit/Blood Contamination Response

Annex

The following discussion gives the rationale behind the remediation recommendations. Fecal contamination of recreational water is an increasing problem in the United States and other countries. Since the mid 1980s, the number of outbreaks of diarrheal illness associated with recreational water has been increasing in the United States.492 Of these outbreaks, disinfected, man-made swimming venues, the target of the MAHC, have had the greatest increase. These outbreaks are usually a result of people swimming while they have infectious, pathogen-containing diarrhea caused by pathogens such as Cryptosporidium, Giardia, Shigella, Salmonella, or E. coli O157:H7. Contamination of swimming water by infected persons and subsequent swallowing of contaminated water by other swimmers continues the spread of diarrheal illness. Diarrheal illness is common in the United States with surveys indicating that 7.2-9.3% of the general public have had diarrhea in the previous month.493 Additional studies demonstrated that people routinely have a mean of 0.14 grams (range = 0.1 to 10 grams) of fecal contamination on their buttocks and peri-anal surface.494 The increase in outbreaks, the high prevalence of diarrheal illness in the public, and likelihood of frequent fecal contamination of POOLS by BATHERS raised the question of how to respond to overt fecal releases, particularly formed stools that were more visible, in POOLS. The need to develop a response plan was amplified by the emergence of the CHLORINE-tolerant parasite Cryptosporidium as the leading cause of disinfected venue-associated outbreaks of diarrheal illness. First, formed stools were thought to be a significantly lower risk for spreading illness compared to diarrhea, since most pathogens are shed in the greatest numbers in diarrhea. As the highest risk material, diarrhea was considered the worst case contamination scenario that could potentially contain Cryptosporidium. As a result, a response should require the extreme treatment conditions needed to inactivate Cryptosporidium. Formed stool was assessed as a lower risk than diarrhea but several questions remained. Should formed stools be treated as potentially infectious materials? If so, then should the stool be treated as a potential Cryptosporidium contamination event like diarrhea (i.e., longer inactivation time) or could it be treated to inactivate all other pathogens other than Cryptosporidium (i.e., shorter inactivation time). To collect data relevant to answering the questions above, a study to collect fecal releases from POOLS in the United States was conducted in 1999. POOL staff volunteers from across the United States collected almost 300 samples from fecal incidents that occurred at water parks and POOLS.495 The Centers for Disease Control and Prevention then tested these samples for Cryptosporidium and Giardia. Giardia was chosen as a representative surrogate for moderately-CHLORINE resistant pathogens like hepatitis A virus and norovirus. Using conditions to inactivate Giardia would inactivate most pathogens other than Cryptosporidium. None of the sampled feces tested positive for Cryptosporidium, but Giardia was found in 4.4% of the samples collected. These results suggested that formed fecal incidents posed only a very small Cryptosporidium threat but should be treated as a risk for spreading other pathogens such as Giardia. As a result of these data and the discussion above, it was decided to treat formed stools as potential Giardia contamination events, and liquid stool as potential Cryptosporidium contamination events. It was thought that norovirus contamination posed the greatest threat from vomit contamination and that the virus would be inactivated by a formed stool response using Giardia inactivation times as discussed above. Further assessment also suggested that blood contamination of POOL water posed little health risk due to the sensitivity of bloodborne pathogens (e.g., viruses, bacteria) to environmental exposure, dilution in the water, and chlorination. In addition, POOL water exposures would lack the requisite bloodborne exposure routes needed to spread the pathogens to other people.

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