The first signs of Listeria (listeriosis) often resemble a mild flu, appearing 1–4 weeks after eating contaminated food, though symptoms can take up to 2 months to develop. Initial signs include fever, muscle aches, fatigue, headache, chills, and diarrhea or nausea.
Gastrointestinal symptoms usually appear within a few hours to 2 to 3 days but can sometimes appear 2 to 6 weeks after eating the contaminated food. In some cases, it may take up to 2 months for symptoms to appear. In healthy individuals, listeriosis typically causes mild symptoms which last for only a few days.
For adults over 65 and those with weakened immune systems, such as people undergoing chemotherapy or living with HIV/AIDS, listeria can spread to the nervous system, causing headaches, stiff neck, confusion, loss of balance and seizures.
Other symptoms may include vomiting, joint pain, headache, and body pain. This form of listeriosis has a much shorter incubation period, with symptoms typically occurring within 24 hours after a person ingests a high number of the bacteria. The illness is usually mild and goes away on its own.
If you eat listeria-contaminated food, you can see symptoms as early as the first day. Listeria is unusual in that it can stay in your body without causing illness for as long as 70 days. This longer period between ingestion and sickness may be especially true in pregnant women.
For the less severe, non-invasive listeriosis, mild symptoms such as fever, muscle aches, nausea, vomiting, and diarrhea may occur, and often persists for 1 to 3 days.
Simply swab the test area and wait. A change in color after 24 – 48 hours of incubation is considered a presumptive positive. No expensive lab equipment is required and no additional sample handling is necessary. InSite® Listeria is an easy-to-use, self-contained, environmental Listeria species test.
Listeria monocytogenes is a gram-positive bacterium that causes serious infections in elderly and immunocompromised hosts. Penicillin, ampicillin, amoxicillin, and gentamicin are recommended for the treatment of Listeria infections.
What to do if you think you ate something with listeria?
Let the healthcare provider know if you ate possibly contaminated food. This step is especially important if you are pregnant, are 65 years or older, or have a weakened immune system. If you ate food possibly contaminated with Listeria and do not feel sick, most experts believe you do not need tests or treatment.
An estimated 1,600 people get listeriosis each year, and about 260 die. The infection is most likely to sicken pregnant women and their newborns, adults aged 65 or older, and people with weakened immune systems.
Most people develop diarrhea, fever and stomach (abdominal) cramps within 8 to 72 hours after exposure. Most healthy people recover within a few days to a week without specific treatment. In some cases, diarrhea can cause severe dehydration and requires prompt medical attention.
For food poisoning, the best drinks are water, oral rehydration solutions (ORS like Pedialyte), clear broths, diluted fruit juice, and sports drinks, sipped slowly to replace lost fluids and electrolytes; avoid caffeine, alcohol, and sugary sodas as they worsen dehydration. Rest and small sips are key, with ORS recommended for vulnerable people like the elderly or young children.
The germs that cause a listeria infection also can spread through the blood and into the brain and spinal cord. If this happens, you might have: Fever and chills. Flu-like symptoms such as muscle aches and fatigue.
The antimicrobial regimen should be the standard therapy for listeriosis, typically including IV ampicillin and gentamicin for 14 to 21 days for nonallergic patients. If blood culture is negative and symptoms resolve, antibiotic therapy may be discontinued.
Not everyone infected with Listeria will develop symptoms. Symptoms could include diarrhea, fever, muscle pain, joint pain, headache, stiff neck, backache, chills, sensitivity to bright light, and/or sore throat with fever and swollen glands. These symptoms can begin days to weeks after eating contaminated food.
How long does the gut take to heal after food poisoning?
While symptoms of the acute illness typically resolve within a few days to a week, the gut's recovery can take longer. In many cases, complete restoration of the gut's microbiome and healing of the intestinal lining can take several weeks to months (1).
Often, healthcare professionals do a blood test to find out if you have a listeria infection. Samples of spinal fluid might need to be tested as well. If you're pregnant, the fluid that surrounds your baby during pregnancy also might be tested.
