Abdur Rasheed, in-charge of Jashore 250-bed hospital, said that Islam and Zakir were admitted to the hospital on 25 January.
Islam died later on Thursday afternoon while Zakir died on Friday morning.
Three other people were admitted to the hospital and are being treated.
Najmul Hasan, sub-inspector (SI) of Narendrapur police camp, said the relatives of the deceased took the bodies to their homes and buried them. He said, ‘The police is probing the matter.