Health officials reported last weekend that at least 57 swimmers who competed in swimming events at the World Triathlon Championship Series in Sunderland fell ill and suffered from vomiting and diarrhea.

Nearly 2,000 individuals gathered for the event which included a swim off Sunderland's blue flag Roker Beach. The UK Health Security Agency, or UKHSA, stated that samples from people who were unwell will be tested to determine the cause of illness and any common parasites.

On Wednesday, July 26, three days before the incident, an Environment Agency survey at Roker Beach did sampling, which showed 3,900 E Coli colonies per 100ml, more than 39 times higher than usual readings the previous month. E coli is a bacterial infection that can cause abdominal discomfort and bloody stools.

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British Triathlon, the country's triathlon governing organization, stated that the agency's sample findings were not disclosed until after the weekend's activities and were outside the body of water where the contests were held. It claimed that its own testing findings met the event's requirements.

The event took place on a stretch of beach that has been the site of a long-running dispute between environmentalists and the government over sewage spills and regulatory failings.

Northumbrian Water argued that it was not to fault for the illnesses and that no discharges that may have harmed the water quality at Roker Beach had been recorded before October 2021.

Australian triathlete Jacob Birtwhistle posted the Environment Agency’s results on Instagram, divulging that he has been feeling "rubbish" since the race and expressing that it should have been canceled.

Another athlete responded to Birtwhistle's post, confirming that they and others had also been ill after the weekend.

According to 51-year-old swimmer Ailith Eve Harley-Roberts, although she likes swimming outdoors, she expressed she has no faith in the quality of water in "seas, rivers, lakes, etc because of the dumping of sewage or other effluents.”

Eva Perrin, science and research officer at campaign group Surfers Against Sewage, confirmed that the levels of E coli shown on July 26 were unprecedented and were "well over what is natural for this water body or safe for human recreational use, and urgently needs to be investigated.”

According to data supplied by the Rivers Trust, based on water business reports, a sewer storm overflow spilled into the Wear Estuary, near the triathlon event, 28 times in 2022 for a total of 370 hours. These sewage discharges would not damage Roker Beach, according to Northumbrian Water, because they were "intercepted" and disposed of by a long-sea outfall.

The triathlon event in Sunderland was the British leg of the World Triathlon Championship Series, and it took place during the qualification period for the Olympic Games in Paris in 2024. Sunderland hosted the UK leg of the series for the first time.

British Triathlon stated that it was collaborating with Sunderland City Council and the UKHSA to determine the source of the infections. According to Environment Agency officials, the sample on July 26 was delayed until July 31 because it required laboratory examination.

According to the UKHSA, Those affected are encouraged to contact organizers to pass details on to the North East Protection team in order to "undertake an investigation of cases."

Water quality may be affected by a variety of circumstances, including the utilization of sewage overflows controlled by water companies and run-off from roads and fields. Northumbrian Water stated that none of its infrastructure was engaged in any pollution problems that may have harmed the triathlon competitions.

A Northumbrian Water spokesperson stated that “we have had no discharges from any of our assets that might negatively impact water quality at either Roker or the neighboring Whitburn North bathing water since October 2021," adding that “both bathing waters were designated as ‘Excellent’ in the latest Defra classifications, and sampling to date in the current season indicate this high quality is being maintained.”