A two-year-old boy on Tuesday became the first child to die in an outbreak of E. coli O104 in Germany, taking the death toll to at least 37.

Some 3,255 people have also fallen sick in 14 European countries plus the United States and Canada, according to the World Health Organisation. Of those, 782 are seriously ill with hemolytic uremic syndrome.

The agricultural ministry in Lower Saxony said Sunday that it is still not clear how sprouts from a farm in the state became contaminated with the bacteria.

"It is not clear whether an employee brought the bacteria into the company or whether it was brought in with seeds which then contaminated the worker," the ministry said in a statement.