At least 100 daycare-aged children in Central Finland who were taken to the hospital for diarrhoea symptoms have been diagnosed with salmonella bacterial infections.
Most of the cases were reported in Jyväskylä, but there were other cases in areas surrounding the city.
Jyväskylä chief paediatrician, Ole Andersen, said it's likely there are many more cases that haven't been reported.
The city's head physician, Ilkka Käsmä, said that almost none of the cases required hospital treatment.
Central Finland's Central Hospital's infection unit and health inspectors are trying to track down the salmonella contamination's source.
Regional health inspector Mia Kappanen said that the only link between the cases was that all of the infections were seen in kids who attend daycare. However, they were enrolled at different day care centers and she said it was unclear whether they all used the same food services provider.
"Investigations into the origin of the salmonella are still in the early stages," she said.
Not the water, but maybe the food
However, as of Thursday authorities ruled out local drinking or swimming water as the culprit, she explained.
Paediatrician Andersen said that the city's health services department has notified the Institute for Health and Welfare (THL) about the epidemic. The institute is expected to also open an investigation on tracking down the source of bacteria.
Local health authorities have already contacted the city's central kitchen. On Monday samples taken from the facility will be sent for laboratory tests.
Kids with symptoms of fever and diarrhoea need plenty of water, or they risk getting dehydrated, according to Andersen. He also recommended giving children medication to reduce high fevers, saying that when temperatures are brought down, the risks of dehydration are also reduced and kids are more able to drink enough water.
"I recommend checking out unusually ill children. Kids with severe conditions should be brought to the hospital for assessment," he advised.
Salmonella infections are often caused by food poisoning during warmer times of the year, as salmonella bacterium multiplies rapidly in foods left at room temperature that should be refrigerated.
Salmonella is a bacterium of animal origin with an incubation period of one to three days and the symptoms from infections usually last 4 to 10 days.
Symptoms of the illness include fever, diarrhoea and, in some cases, vomiting.