By Beauttah Omanga and Cyrus Ombati
Eight prisoners died at the Kamiti Maximum Prison following an outbreak of a diarrhoeal disease.
A Government team on Sunday toured the facility and announced measures, including isolation of those affected.
"We will isolate those with signs of the disease until we ascertain the cause," said Prison Commandant Isaiah Osugo.
Director of Public Health Shahnaaz Shariff ruled out cholera and called for patience as tests were carried out.
Mr Osugo said 22 inmates were admitted to Kenyatta National Hospital (KNH), while 32 were being treated at the institution’s health facility.
He termed the outbreak the worst to ever hit a correctional facility.
The latest deaths bring to nine the number of the inmates who have succumbed to the disease.
There were fears more prisoners may succumb because of congestion. The outbreak was noticed on Friday night when some infected prisoners started to diarrhoea and vomit.
On Saturday, one died before authorities called in doctors from KNH. Insiders said the situation got worse when KNH declined to admit all patients, saying their wards were full.
The seven died on Saturday night as they underwent treatment.
On Sunday, prison authorities and officials from the Ministry of Health and Nairobi Water Company met at Jogoo House. Dr Shariff said water at the facility was found to be safe.
Osugo said: "In modern maximum prisons, there are about 500 prisoners, which is easy to manage. But we have more than 3,000 prisoners."
And the Kenya National Commission on Human Rights called for intervention to curb spread of the outbreak.
Addressing a press conference after visiting Kamiti, Commissioner Fatuma Dullo said although the situation was temporarily under control, chances of it spreading were high.
KNCHR Vice-Chairman Hassan Omar petitioned the Ministry of Finance to allocate more funds to the Prisons department.
He also urged the Government to upgrade prison health centres to district hospital status.