Listeria-tainted rockmelons: What you need to know about the bacteria

Four people in Australia have died after eating rockmelons contaminated with listeria, in an outbreak that has so far affected 17 people.

The source of the rockmelons were traced back to a farm in New South Wales, leading to a recall in Singapore by the Agri-Food and Veterinary Authority (AVA). 

Here's what you need to know about listeria.

WHAT IS LISTERIOSIS?

Listeriosis is a bacterial infection caused by Listeria monocytogenes.

WHERE IS IT FOUND?

The bacteria is found in the environment, such as soil, water, effluents and the faeces of humans and animals. 

HOW DOES IT SPREAD?

It can contaminate food anywhere during production process from harvesting to serving.

WHAT TYPES OF FOOD CAN GET CONTAMINATED?

Food items which could be contaminated by the bacteria include raw or ready-to-eat foods, such as raw (unpasteurised) milk or raw meat and their products, seafood, and fresh produce including fruits and vegetables.

WHAT ARE THE SYMPTOMS?

The incubation period of listeria ranges from three to 70 days (typically one to four weeks). 

A person with mild listeriosis usually has fever and muscle aches, preceded by diarrhoea or other gastrointestinal symptoms.

Pregnant women, the elderly or individuals with a weakened immune system, i.e. people in immuno-compromised status due to AIDS, leukaemia, cancer, solid-organ transplant and steroid therapy, are at highest risk of serious disease which could include brain and heart infections or complications in the foetus/newborn.

HOW CAN LISTERIOSIS BE TREATED?

Listeriosis is treatable with antibiotics if diagnosed early. Consumers should seek medical attention as early as possible if they develop fever and muscle aches, preceded by diarrhoea or other gastrointestinal symptoms that appear within 70 days after consuming Australian rock melon.

HOW CAN LISTERIOSIS BE PREVENTED?

The key to prevention of listeriosis lies in hand hygiene, safe handling, cooking and consumption of food. 

People can reduce risk for listeriosis by:

• Thoroughly washing raw vegetables and fruits before eating. Peel them if necessary.
• Thoroughly cooking raw food from animal sources (i.e. beef, pork, poultry, etc.)
• Keeping uncooked meats separate from vegetables, fruits, cooked and ready-to-eat food.
• Avoiding raw (unpasteurized) milk or foods made from raw milk
• Washing hands and kitchen utensils such as knives and cutting boards after handling raw food
• Using separate sets of knives and cutting board for raw and cooked food

klim@sph.com.sg