Oxford Public Health has confirmed that deer meat was responsible for four cases of E.coli in the county and a neighbouring municipality.
The venison was sourced from private hunts and processed privately, at a non-commercial facility, into sausage.
All four cases were reported over the last two months.
Public Health says nine deer meat samples were forwarded to a lab and all testing positive for the bacteria that can cause severe stomach and intestinal problems.
Officials those who had access to the meat should throw it out.