A rare disease, although the causal organism, Listeria monocytogenes, is widely distributed in soil, silage, water, and various animals, with consequent risk of food contamination – for example, from unpasteurised soft cheese. Newborn babies may be at risk as a result of a mild or inapparent infection in the pregnant mother. It presents in two main forms: MENINGOENCEPHALITIS, or SEPTICAEMIA with enlarged LYMPH glands. Elderly adults occasionally develop the first form, while younger adults are more likely to develop a mild or even in-apparent form. The disease is treated with ANTIBIOTICS such as amoxicillin (see PENICILLIN) or CHLORAMPHENICOL.