listeriosis (perinatal)

Last edited 02/2020

Neonatal listeriosis presenting in the first week has a high mortality. About 20% of fetuses infected with Listeria are still born.

The liquor can be stained, and this can be mistaken for meconium.

Reservoir:

• gastrointestinal tracts of humans, birds, cattle, sheep and other animals
• widespread in the environment: soil, vegetation, water, silage/sewage, mammal/fish/bird faeces
• occurs in raw foods, food components and ready to eat foods: most commonly in foods because of contamination from sites in food production environments

Epidemiology:

• listeriosis is a rare but severe systemic infection that includes bacteraemia, meningitis, encephalitis and in pregnant women can lead to miscarriage and stillbirth
• most often affects those who have a weakened immune system including pregnant women, their unborn and new born infants, the elderly and individuals who are immunocompromised by a pre-existing medical condition or treatments for an existing illness
• occasionally, healthy people can become infected
• listeriosis has a high mortality rate of 20-30% and in the UK is the most common cause of death from a foodborne illness. The annual number of laboratory-confirmed cases of listeriosis averaged 180 a year between 2005-14

Transmission:

• majority of cases are foodborne. Cases and outbreaks have been associated with a variety of foodstuffs, the most common in England and Wales being pre-prepared sandwiches but other foods have included soft cheeses, cooked and processed meats (e.g. pâté and sliced meat), smoked fish, butter, olives and melon in the US
• mother-to-baby transmission is important:
• in utero transmission,
• vertical transmission during birth, or
• person-to-person spread soon after delivery
• direct contact with infected animals can occasionally cause infection
• pregnant women, individuals who are immunocompromised and those (< 1 month and >60 years of age) are more susceptible to infection
• L. monocytogenes can be present in the faeces of approximately 5% of the population but is likely to be transitory

Incubation period

• For invasive disease, the incubation period ranges from 1-70 days

Infectivity:

• Not applicable except at and shortly after delivery due to contact (hand or fomites) from an infected infant to an apparently healthy infant who develops meningitis

Reference:

• PHE (2019). Recommendations for the Public Health Management of Gastrointestinal Infections