Clinical Features/Signs and Symptoms

Listeriosis Linked to Raw Milk Produced by Miller’s Organic Farm in Pennsylvania (Final Update)

This investigation is over. This outbreak is a reminder that people should drink and eat only pasteurized dairy products, including milk, soft cheese, ice cream, and yogurt. This recommendation is especially important for people at higher risk for foodborne illness: children younger than 5, pregnant women, adults 65 and older, and people with weakened immune systems.

Listeriosis is a life-threatening infection caused by eating food contaminated with the bacterium (germ) Listeria monocytogenes. The disease primarily affects pregnant women and their newborns, adults older than 65, and people with immune systems weakened by cancer, cancer treatments, or other serious conditions (like diabetes, kidney failure, liver disease, and HIV). Rarely, people without these risk factors are affected.


The symptoms vary with the infected person:

  • Higher-risk people other than pregnant women: Symptoms can include fever, muscle aches, headache, stiff neck, confusion, loss of balance, and convulsions.
  • Pregnant women: Pregnant women typically experience only fever and other non-specific symptoms like chills and headache. However, infection during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
  • Healthy people. Healthy people rarely develop invasive listeriosis. However, people exposed to a very large dose of Listeria bacteria can develop a non-invasive illness (meaning the bacteria do not spread into their bloodstream or other sites) with diarrhea and fever.