Isolated samples were found in Soinaste, Ülenurme, and Tõrvandi, all areas just to the south of Tartu city.

The board noted that it cannot yet be definitively said that this is the cause of a recent wave of illnesses in the area, as in each case the sufferer was in a household where illness cases had already occurred, and there have likely been no new cases related to drinking water consumption, the board said.

The exact cause of the infections and the pathogen are still being determined, as laboratory analysis is ongoing.

As a precaution, the board recommends boiling tap water before use in any case, and to avoid attending group activities like school, work, or events, while sick.

Hygiene rules should be followed when attending to the sick or when cooking - fruit and vegetables should be washed in pre-boiled water.

Since Monday, the board says it has contacted more than 50 people who reported various symptoms the sufferers identify as associated with drinking water consumption.

The board collected samples from the area's drinking water, and on Friday afternoon, the first results arrived, which showed isolated findings of E- coli and similar bacteria.

The board reiterated that these findings do not indicate that the drinking water is extensively contaminated; the isolated bacteria suggest the area's drinking water may have become contaminated last week, however..

Water supplier Tartu Veevärk told ERR that all samples taken from the public water supply were clean, meaning that the bacterial findings must have come from outside the public water system.

Both children and adults have been affected. The acute phase of the illness usually passed within a couple of days, the board said, and most patients reported vomiting (in 78 percent of cases), diarrhea (in 65 percent), fever (39 percent), weakness (27 percent), abdominal pain (24 percent), and nausea (18 percent).

There are various hypotheses about the causes of these illnesses, the board added, since intestinal viral infections, which can cause similar outbreaks, also commonly occur in spring.

The Health Board is continuing to work with the local water provider to establish what may have affected the drinking water quality last weekend.

E.Coli outbreaks were found in drinking water in Kuressaare, Saaremaa's capital, from late spring to autumn, 2023.

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