"We posit the release of a cloud of Legionnaires' that has spread over quite a large space. In this case the Glomma can have been a factor in the dispersal," Preben Aavitsland from the Norwegian Institute of Public Health told NRK (Norwegian Broadcasting).
The deadly Legionnaires' bacteria has been found in several cooling towers for air conditioning systems in the Fredrikstad-Sarpsborg area in southeastern Norway. Technicians are now comparing the DNA profile of these bacteria with those found in infected patients.
Technicians are also working on the basis of a theory that the river Glomma, Norway's largest, can have contributed to the spread of the disease.
Aavitsland said that the extent of the spread of the bacteria could be something completely new, with the disease carrying far longer than what is generally considered to be the maximum distance.
"We are beginning to get a picture of what has happened. It is beginning to become clear that the bacteria must have spread far further than the three kilometers (1.86 miles) given in all the textbooks," Aavitsland told Norwegian news agency NTB.
Interviews with infected patients indicate that the contagion can have spread over a record distance - Fredrikstad and Sarpsborg are 17 km apart.
On Wednesday the official toll for the disease was 35 confirmed infected, five dead and six in serious condition. To increase capacity at Østfold Hospital Fredrikstad 16 patients had been transported to five hospitals in the Oslo region, ØHF said in a statement.
