How Long Do Listeria Symptoms Last?

Medically Reviewed on 12/19/2022
Listeria Symptoms
Listeria monocytogenes infection occurs when people consume or handle contaminated food.

According to the Centers for Disease Prevention and Control, symptoms of listeria usually begin within 24 hours after eating the contaminated food and can last one to three days.

What is listeria?

Listeria is a disease brought on by consuming foods contaminated with the Listeria monocytogenes bacterium. Listeria infection or listeriosis is rare but can be fatal in susceptible individuals, such as older people and those with compromised immune systems. It might be harmful to pregnant individuals and their unborn children.

There are two main types of listeriosis:

  1. Noninvasive listeriosis (febrile gastroenteritis): A mild form of illness that primarily affects normally healthy individuals. Diarrhea, fever, headaches, and myalgia (muscle pain) are some of the symptoms of noninvasive listeriosis. It has an extremely short incubation period. The consumption of foods high in L. monocytogenes has typically been a factor in outbreaks of this illness.
  2. Invasive listeriosis: A more severe form of the disease that affects specific high-risk groups. They include pregnant people; people undergoing treatment for AIDS, cancer, or organ transplants; older people, and parents of young children. The hallmarks of this type of sickness include severe symptoms and a high death rate (20 to 30 percent). Some of the symptoms include fever, myalgia, septicemia, and meningitis. The incubation period, which is normally one to two weeks long, can last anywhere between a few days and up to 90 days.

What are the symptoms of listeriosis?

Serious listeriosis infections have the potential to spread to the brain or bloodstream and may result in sepsis, meningitis, or encephalitis.

Symptoms of listeriosis include:

How are people infected with listeriosis?

Listeria monocytogenes infection occurs when people consume or handle contaminated food. The bacteria get to the mouth or other openings from the hands. If a pregnant person consumed contaminated food while pregnant, their babies may contract the infection in the womb or at delivery.

Numerous foods can become contaminated by the bacteria, such as:

  • Raw meat
  • Ready-to-eat processed meat, such as hot dogs and deli meat (both items served at deli counters and in factory-sealed packets)
  • Raw vegetables
  • Chilled patés
  • Ready to eat uncooked and smoked seafood
  • Salads that have been prepared or kept, such as coleslaw and fruit salad
  • Melons
  • Unpasteurized milk and milk products or soft cheeses produced from them

Listeria monocytogenes bacterium can be destroyed by cooking, pasteurization, and by some disinfectant agents. Reheating ready-to-eat foods to a steaming temperature makes them safe to consume.


Bacterial Infections 101: Types, Symptoms, and Treatments See Slideshow

Who are at risk of listeriosis?

Listeriosis can affect anyone. It is less dangerous for those with a strong immune system.

The following people are at a high risk of dying or getting severely ill due to listeriosis:

  • People aged 65 years or older
  • Pregnant people
  • Developing fetuses
  • People with a weakened immune system (for example, people with AIDS or cancer or who are taking prescribed immunosuppressive medications)

How to prevent listeriosis

Those who are more vulnerable should adhere to the following food safety precautions to prevent infection:

  • Only consume or serve completely cooked food derived from animal products
  • Dairy products should have a pasteurization statement on the label before consumption
  • Do not consume raw (unpasteurized) milk or products made with it (for example, unpasteurized feta, brie, and queso fresco)
  • Wash fruits and vegetables
  • Store prepared foods at 40 °F or lower temperatures
  • Do not combine vegetables and raw meat
  • After handling raw foods, wash your hands, knives, and cutting boards
  • Cook ready-to-eat meals, such as hot dogs and leftovers, completely until they are piping hot
  • Avoid eating prepackaged salads, meats, or cheeses from delis, or reheat them to a steaming temperature before eating
Medically Reviewed on 12/19/2022
Image Source: iStock image

Get the Facts about Listeria.


Listeriosis in Infants, Children & Pregnant People.

Listeria (Listeriosis).

Listeria (food poisoning).