The diarrhea broke out Oct 6 in north Dum Dum, in the state's North 24 Parganas district and since then both adults and children are being brought to the three hospitals as well as medical camps organised by the health department.
The situation is now under control, said B.R. Satpathi, director of health services.
"The municipal water source is grossly contaminated and that led to the outbreak. More than 300 people have been affected and are being treated at the health camps of the state health department," Satpathi told IANS.
Around 17 medical teams are engaged in treating the sick while six camps have been set up to provide relief.
Satpathi also blamed the north Dum Dum municipality authorities, now under the Left Front.
"The sanitation needs improvement...perhaps those incharge of the north Dum Dum municipality are not taking proper care," added Satpathi.