Background

Listeria monocytogenes usually transmitted via contaminated food, occasionally direct person to person.

  • Rising incidence (17 cases recorded in Ireland 2007)
  • Pregnant women have x20 times the risk of infection
    • With risk of: abortion, premature delivery, stillbirth, neonatal infection
  • Severe in immunocompromised (including diabetics) and elderly
  • Significant cause of food poisoning deaths (mostly infants and elderly)
  • Incubation: 3 - 70 days (most <3 weeks)
  • May remain infectious for months

Foodstuff

Listeria monocytogenes is widespread in environment (soil, water, vegetables

  • Sensitive to adequate heat and pasteurisation
  • Can multiply at low temperatures
  • Non-pasteurised milk products
  • Soft cheeses, coleslaw
  • Raw vegetables, smoked salmon, pâté

Symptoms Listeriosis

  • Asymptomatic ! (particularly pregnant women)
  • 'Flu (mild fever, myalgia, nausea)
  • Headache, meningism, convulsions

Diagnosis

  • Blood or CSF culture
  • Serology not useful

Treatment

  • Penicillin +/- aminoglycosides or
  • Co-trimoxazole or erythromycin

Prevention

  • Handwashing
  • Wash raw vegetables and kitchen surfaces
  • Separate raw and cooked meat
  • Avoid unpasteurised milk etc
  • Ensure microwave food is heated properly (stir 1/2 way through cooking)

For high risk people

As left and (esp. pregnant women):

  • Avoid ripe soft cheese, pâté or smoked fish
  • Avoid lambing or milking ewes
  • Be very careful if caring for someone with diarrhoea (hand washing ++)