Symptoms
Signs and symptoms of Listeria infection vary depending on the person infected and the part of the body affected.
The bacteria are most likely to sicken people who are pregnant and their newborns, adults aged 65 or older, and people with weakened immune systems. Other people can be infected with Listeria, but they rarely become seriously ill.
Invasive illness
Invasive means bacteria have spread beyond the intestines (gut). Invasive listeriosis happens when Listeria have spread beyond the intestines.
Symptoms of invasive illness usually start within 2 weeks after eating food contaminated with Listeria.
People who are pregnant
Symptoms typically include
- Fever
- Flu-like symptoms, such as muscle aches and fatigue
People who are not pregnant
Symptoms typically include
- Fever
- Flu-like symptoms, such as muscle aches and fatigue
- Headache
- Stiff neck
- Confusion
- Loss of balance
- Seizures
- Symptoms in pregnant people are usually mild. Some pregnant people never have symptoms.
- However, infection during pregnancy usually leads to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
- Symptoms in non-pregnant people can be severe.
- Almost 1 in 20 non-pregnant people with invasive listeriosis die.
Intestinal illness
Listeria can also cause an intestinal illness. This kind of illness is rarely diagnosed because laboratories do not regularly test patient stool (poop) samples for Listeria.
Symptoms of intestinal illness usually start within 24 hours after eating food contaminated with Listeria and usually last 1–3 days.
Symptoms typically include
- Diarrhea
- Vomiting
- Symptoms are usually mild.
- However, some people with intestinal illness develop invasive illness.
