General Information

Listeria - Clinical information

Incubation period

Variable, 3 to 70 days.

Common clinical features

Influenza-like illness or meningo-encephalitis/septicaemia; spontaneous abortion. Maternal infections can be asymptomatic.

Reservoir

Environment, cattle, sheep, soil, silage. The bacterium has been isolated from a range of raw foods including vegetables and uncooked meats as well as processed foods. A wide range of food products have been implicated in outbreaks including soft cheeses and meat based patés. Commonly carried in the human gut.

Transmission

The majority of cases are believed to be foodborne. Some cases by direct contact with animals. Mother to foetus in utero or during birth or via person to person spread between infants shortly after delivery.

Other relevant features

Unborn infants, neonates, immunocompromised individuals, pregnant women and the elderly are at high risk. Cases are usually divided into those associated with pregnancy (mother-foetus and mother-neonate cases) and non pregnancy associated cases - all cases aged 1 month and over.