Warders and inmates at Daru prison diagnosed with typhoid and malaria are calling on Papua New Guinea authorities to move them out immediately.
Daru prison's acting commander Inspector Dura Geru is among eleven staff and prisoners being treated at the local hospital.
But The National newspaper reports Mr Geru is warning that there is a high possibility of a typhoid fever breakout in the prison.
He says warders contracted typhoid and malaria after having to work 12-hour shifts in appalling conditions at the prison's mosquito-ridden facilities.
Provincial health officials condemned the facility last month but nothing was done to fix the health and safety issues highlighted in time for a mid-February deadline.
Mr Geru says they are therefore "illegally working and living" at the prison.
The Correctional Service Department is reportedly compiling an assessment report about the state of the prison.
Typhoid is a bacterial infection that can lead to a high fever, diarrhoea and vomiting. It is caused by the bacteria Salmonella typhi.
The typhoid diagnoses come as Daru struggles with tuberculosis, leprosy and chronic health problems linked to poor sanitation.
Last week, the mayor of the Western Province capital warned that coronavirus could "wipe out" Daru if it reached his town.