Listeriosis can occur at any time in pregnancy. Patients may be asymptomatic, only being diagnosed after developing problems around delivery, or in the neonate.
- in a case series of listeriosis in pregnancy (2)
- 32% of women had symptoms of a flu-like illness
- 65% had a fever
- other symptoms included backache (21.5%) (which may be mistaken for a urinary tract infection)
- headache (10.5%)
- vomiting/diarrhea (7%)
- muscle pains (4%)
- sore throat (4%)
- approximately 29% of the women were asymptomatic
Listeriosis occurs in 6-15/100,000 pregnancies.
Generally, perinatal infection occurs in the second or third trimester.
Diagnosis is made on the basis of clinical picture and blood culture.
Summary listeriosis:
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
- due to a listeria outbreak linked to smoked fish, people at higher risk of serious infection should only eat smoked fish products that have been thoroughly cooked (4)
- when cooking smoked fish products at home, make sure they are steaming hot all the way through
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
Clinical Features:
- initial symptoms of listeriosis include fever and flu-like symptoms, which may or may not be preceded by a febrile gastroenteritis. Pregnant women may be asymptomatic or have mild symptoms. A person of any age and immune-state may experience any of the following symptoms or remain asymptomatic. Below are the most common presentations for particular patient groups
- Healthy adults and older children:
- Asymptomatic infection
- Acute gastroenteritis with fever
- Non-specific symptoms such as fever, muscle aches, headache
- (often goes undiagnosed/unrecognised)
- Pregnant women
- no/mild non-specific flu-like symptoms (as above)
- foetal loss, stillbirth, pre-term delivery with severe infection in the newborn (some with pre-term delivery) and neonatal meningitis
- Immunosuppressed persons / older adults
- septicaemia, meningitis or meningo-encephalitis
- Immunocompetent persons can also present with severe disease such as septicaemia or meningitis
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:
- Benshushan A et al. Listeria infection during pregnancy: a 10 year experience. Isr Med Assoc J. 2002 Oct; 4(10):776-80.
- Mylonakis E et al.Review Listeriosis during pregnancy: a case series and review of 222 cases.Medicine (Baltimore). 2002 Jul; 81(4):260-9
- PHE (2019). Recommendations for the Public Health Management of Gastrointestinal Infections
- NHS Conditions. Listeriosis (Accessed 27/4/22)