Cause of outbreak at Laugarvatn still unknown

Twelve people have reported illness to the Chief Epidemiologist following a triathlon held at Laugarvatn over the weekend. The symptoms are very similar among those affected, consisting of vomiting, diarrhea, fever, and body aches. It is clear that a group infection is involved, but the cause of the outbreak remains unknown.

This was stated by Guðrún Aspelund, Chief Epidemiologist, in an interview with mbl.is . She said that although only 12 reports have been received by her office, more people are known to have fallen ill. Those who became ill are encouraged to undergo testing so that the pathogen causing the illness can be identified.

The illnesses were first reported yesterday by mbl.is after one triathlon participant posted in the Facebook group Triathlons in Iceland , describing symptoms of stomach flu following the competition.

Around forty people have commented on the post, saying they also experienced similar symptoms after the event. It has been speculated whether the infection could be linked to hamburgers offered to participants after the race, or if Laugarvatn itself was contaminated, as competitors swam 1,500 meters in the lake.

Symptoms resemble norovirus infection

Guðrún Aspelund said that all those who reported illness had been at Laugarvatn on Saturday when the competition was held, although not all had swum in the lake or eaten the hamburgers. Some who neither swam nor ate the hamburgers, but still became ill, had been in close contact with those who had.

“The symptoms are nearly identical between individuals and very similar to those of a norovirus infection, which can spread in groups where people are in close contact for any reason. Everyone seems to have in common that they were at the event,” said Aspelund.

The Chief Epidemiologist has been in contact with the South Iceland Health Inspectorate regarding the illnesses. The health authorities will decide whether a water sample should be taken from the lake.

No water samples taken for two years

Sigrún Guðmundsdóttir, director of the South Iceland Health Inspectorate, told mbl.is that they are awaiting test results from those who fell ill after the competition to help determine the source of the infection. If the results suggest the lake was the source, water samples will be taken from Laugarvatn.

When asked, Guðmundsdóttir said that the health authorities have not taken any water samples from the lake in the past two years.

“Significant improvements have been made to the wastewater systems in Laugarvatn, and it hasn’t been considered necessary to test the water,” said Guðmundsdóttir.

Contamination has been detected in Laugarvatn on several occasions. The last recorded incident was in 2023, when fecal contamination was found in the lake.