Travel Health Service Listeriosis
Travel related diseases


What is listeriosis?

Listeriosis is a serious food-borne infection in human caused by consumption of food contaminated with the bacterium Listeria monocytogenes. Listeriosis also affects a variety of animals. A large variety of food can contain listeria, including unpasteurised milk, soft cheeses, ready-to-eat meats, and seafood. Listeria may grow slowly even at refrigeration temperature.

Listeriosis occurs worldwide, with sporadic incidence. It affects primarily pregnant women, newborns and adults with weakened immune system. A person with Listeriosis has fever, muscle aches, and sometimes gastrointestinal symptoms such as nausea or diarrhoea. In serious cases, there is meningitis or septicaemia. Infected pregnant women may experience only a mild, flu-like illness. However, infections during pregnancy can lead to miscarriage or stillbirth, premature delivery or infection of the newborn. The mortality rate ranges from 30% to 70 %.

How does it spread?

Listeria monocytogens is found in soil and water, so vegetables can be contaminated. Animals can carry the bacterium without illness. Unpasteurised milk or food made from unpasteurised milk may contain the bacterium.

People get listeriosis by eating food contaminated with Listeria. Babies can be born with Listeriosis if their mothers consume contaminated food during pregnancy.

How can you prevent?

Risk for travellers is generally low. Risk is increased by consumption of unpasteurised milk and its products. Travellers can protect themselves by observing good personal hygiene and food hygiene, avoiding risky food and drinks e.g., food and beverages from unhygienic food vendors, undercooked food from animal sources, such as beef, pork, poultry, raw vegetables and unpasteurised milk. Keep uncooked meats separated from vegetables, cooked and ready-to-eat foods. Avoid eating ready-to-eat food which has been refrigerated for more than one day. Wash hands, knives, and cutting boards after handling uncooked food.

For high risk groups, such as pregnant women and immunocompromised persons, they should avoid unpasteurised milk, soft cheeses and raw vegetables and should cook food thoroughly.

How is it treated?

Listeriosis can be treated with antibiotics.