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The World Health Organization (WHO) provides technical advice to national authorities in Brazil on matters of public health, and to the International Olympic Committee (IOC) and local organizing committee (LOC) on health issues associated with visitors and athletes attending the Olympic Games. In response to questions about health risks from sewage pollution at venues where Olympic athletes will be in water, in sailing, rowing, canoeing and swimming events, WHO recommends that national authorities follow the WHO Guidelines for Safe Recreational Water Environments to protect public health.
These guidelines recommend classifying water quality through a regular and ongoing program of microbial water quality testing, using enterococci and E.coli and sanitary inspection to identify health risks to bathers from pollution of bathing waters.
Available evidence suggests that the most frequent adverse health outcome associated with exposure to fecally contaminated recreational water is enteric illness, such as self-limiting gastroenteritis, often of short duration. Transmission of pathogens that can cause gastroenteritis is biologically plausible and is analogous to waterborne disease transmission in drinking-water, which is well documented.
Testing using standard bacterial indicators is the basis of current global guidelines for monitoring bathing water in the context of public health. The presence of fecal indicator bacteria indicates the presence of faecal contamination, which can be assumed to contain pathogenic bacteria, viruses and protozoa.
Epidemiological data shows that bacterial testing, especially enterococci, is the indicator with the strongest evidence for it being a predictor of gastrointestinal illness from marine bathing water impacted by human fecal contamination, including illness from viruses.
Efforts should be directed toward preventing contamination as far as possible from the sources identified through sanitary inspections, and to limiting exposure of athletes and the public to contaminated water. Water quality testing, over and above recommendations in the WHO guidelines, should not distract attention and resources away from measures to address the sources of pollution.
WHO does not currently recommend testing of viruses for routine monitoring because of a lack of standardized methods and difficulty interpreting results. There are specific exceptional circumstances where viral testing may add value:
- As part of an investigation into a confirmed outbreak of disease where there may be a viral cause;
- As part of a formal research protocol to improve understanding of the role of viral contamination of recreational water (e.g, research to investigate circumstances in which bacterial indicators organisms may have been removed through treatment or natural processes but viruses persist).
Outside these circumstances viral testing is not recommended in the current international guidelines.