Investigators in Ostersund, Sweden, say they traced a cryptosporidium outbreak that has sickened more than 11,000 residents to a multifamily dwelling in the city’s Odensala neighborhood

Ostersund environmental head Jari Hiltula told Swedish news agency TT,

"We’ve found high levels of the parasite in the connection to this source. We’ve handed over the information to the police who are responsible for the investigation. A property owner will also be contacted."

The parasite may have entered the city’s water supply through a sewage line mistakenly connected to a rainwater drainage system, the report said.

"It looks like the sewage pipe wasn’t connected properly," said Andrew Sorensson, an environmental crimes investigator with the Ostersund police.

The water system in Östersund, in northern Sweden, has been found to contain an area with high levels of cryptosporidium which has left thousands of people ill and the city’s water undrinkable.

Östersund municipality is now considering how the area can be sealed off so that the parasite does not continue to reach the water treatment plant, it was revealed at the press conference (photo from The Local).

Those responsible at the municipality would not reveal if the area was found in water or on land.

The details of the tests were passed on to police and prosecutors this morning.

Nearly one in ten residents of Östersund has now been hit by a stomach bug caused by the parasite in the municipal water supply.

Two operating rooms at Östersund Hospital are today closed due to the rampaging stomache flu.

The infection has hit hospital staff – with almost 200 workers at home from work on Thursday, according to Sveriges Television (SVT). Hospital management expects an increasing number of sick staff over the next few days.

The hospital has 3000 liters of clean water driven in every day in order to secure water supplies.

Police said today a criminal investigation is under way in Sweden to determine how an intestinal parasite ended up in the town of Ostersund’s municipal water supply, sickening more than 2,000 residents.

Environmental prosecutor Christer B. Jarlas said release of the parasite cryptosporidium may have been the result of criminal negligence, the Swedish news agency TT reported Tuesday.

He said he has reason to believe that the contamination was due to carelessness by one or several individuals who didn’t have control of their operations.

Sweden’s National Center for Infectious Disease Control told TT the 50,000 residents of Ostersund will have to boil their water for several weeks.