Listeriosis Symptoms, Signs, and Diagnosis

What are Listeria infection symptoms and signs?

In most people, Listeria infection symptoms and signs mainly include the common symptoms of food poisoning such as

If Listeria causes more severe illness, patients may also experience

At-risk patients (such as immune-compromised individuals) may become very ill or even die from a Listeria infection.

How is listeriosis diagnosed?

Listeriosis is diagnosed based on the results of medical tests. These tests may include the following:

  • Stool culture: A stool sample is tested in the lab for the presence of the Listeria bacterium. Results from this test may take several days to return.
  • Blood tests: These tests may indicate the presence of infection or tell the doctor how sick someone is, but they are not able to pinpoint Listeria as the cause unless blood cultures are done. Blood cultures are used to isolate the specific bacteria that are causing the infection and may show Listeria.
  • A "spinal tap” (lumbar puncture): Cerebrospinal fluid (CSF) is taken from a needle placed in the lower back. Microscopic testing and cultures are done on this fluid and may show the presence of Listeria.
  • Cultures of amniotic fluid may be used in at-risk pregnant patients who develop symptoms of listeriosis.

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Medically reviewed by Robert Cox, MD; American Board of Internal Medicine with subspecialty in Infectious Disease


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