Listeriosis Flashcards
What is the infectious agent for listeriosis?
Listeria monocytogenes
Human listeriosis is caused by a single species of Listeria - Listeria monocytogenes.
What are the main modes of transmission for listeriosis?
Contaminated food (most common) and vertical transmission to foetus/newborn
Listeria is ubiquitous in the environment and may be isolated from soil, surface water, decomposing organic matter, spoiled silage, sewage, commercial foodmanufacturing environments, raw foods including vegetables, meats and dairy products and
is carried in the gastrointestinal tract of many animals.
What is the incubation period for Listeria?
Up to 70 days after exposure.
Median incubation for:
Invasive listeriosis (CNS involvement) = 9d
Invasive listeriosis (bacteraemia) = 2d
Pregnancy-associated = 27.5d
Non-invasive = very short: 24 hours
What is the infectious period for listeriosis?
Horizontal person-person transmission is uncommon therefore infectious period is not relevant routine public health practice.
What are the main two broad clinical presentations of Listeriosis?
Invasive - sepsis, meningoencephalitis, vertical
Non-invasive - gastrointestinal; food poisoning
Who is at increased risk of listeriosis?
Immunocompromised, elderly, pregnant, newborn, chronic medical conditions, on gastric acid inhibitors.
What is the public health significance of listeriosis?
Invasive listeriosis is relatively rare but the disease severity and involvement of commercially manufactured foods mean that the social and economic impact is among the highest of the foodborne diseases.
Clinical impact is much less for non-invasive listeriosis.
For high-risk groups, what are the dietary recommendations for foods to avoid?
Cold meats, cold cooked chicken, pate, salads (pre-prepared/packaged), chilled seafood (raw, smoked, ready to eat), cheese (soft, semi-soft, surface ripened), ice cream (soft serve), unpasteurised dairy products (raw milk)
Listeria case fatality rate
25-50% among non-pregnant adults despite adequate antimicrobial treatment.
Who are the typical stakeholders involved for a foodborne outbreak?
Public Health Unit, Communicable Disease Branch, OzFoodNet, FSANZ
What length of isolation and restriction required for listeriosis?
Unnecessary
When should active case finding be initiated for listeriosis?
When there is evidence of a cluster of cases or of common exposure to a suspect source.
What contact management is required for listeriosis?
Person-to-person transmission does not usually occur, so identifying contacts is not usually relevant for listeriosis. Nor is antimocrobial prophylaxis.
What environmental and food evaluation is required for listeriosis?
Food premises investigation to ensure adequate food safety practices and testing of suspected foods.
