Risk factors for listeriosis in Denmark, 1989-1990.

Dietary risk factors for listeriosis were examined, and the risk levels of listeriosis according to specific underlying diseases were evaluated, in order to study the basis for prevention. Questionnaires from 50 listeriosis patients and 40 matching control persons were analysed. Unpasteurized milk was a risk food for sporadic listeriosis, and an outbreak of a European epidemic strain of Listeria monocytogenes was obviously linked to a blue-mould cheese or a hard cheese. Leukaemia, AIDS and renal transplantation were found to be associated with > 1000-fold risk of acquiring listeriosis, compared with healthy persons. As a part of prevention, persons running a high risk of contracting listeriosis should be individually informed about food hygiene and risk foods.