Eight of the same family were hospitalised yesterday in Barguna's Patharghata upazila, a day after one other member of their family died after exhibiting similar symptoms.
The symptoms all nine have are: fever, nausea and diarrhoea.
The eight Tengra village locals were admitted to the upazila health complex, with three of them said to be in critical condition, reports our Patuakhali correspondent quoting doctors.
Earlier on Tuesday, Manik, 30, of the same family died after showing similar symptoms.
The eight patients still in hospital are: Manik's son Saiful Islam, 9; his younger sister Minara Begum, 30; nieces Parvin, 22, Shahrin, 11, Jannat, 9, and Ema, 11; nephew Zarif, 6; and cousin Nasrin, 30.
Among them, Minara, Shahrin and Emar are in critical condition, said Dr Saidul Arefin, resident physician at the health complex.
After news of the incident spread, locals began to panic.
The resident physician, however, said there was no reason to panic.
It is primarily suspected to be a case of food poisoning and the authorities are dealing with the issue with due importance, since eight of a family have fallen ill at a time, said Barguna Civil Surgeon Dr Humayun Shaheen Khan.
The patients have been referred to Barishal Sher-e-Bangla Medical College and Hospital for better treatment, said Dr Abdul Fattah, health and family planning official of the upazila.
The patients were still being treated at the health complex till filing of this report.
If necessary, the patients will be sent to Dhaka for better diagnosis and treatment, the civil surgeon said.