Listeriosis is a communicable disease which could present with fever, muscle aches, nausea and diarrhea. If the infection spreads to the nervous system the person may experience headache, stiff neck and confusion. In adults it is primarily acquired through the consumption of unpasteurized dairy products such as milk, soft cheeses and processed ready to eat meat such as hot dogs. Those at the highest risk for the disease are (1) newborns (2) pregnant women (3) people with weakened immunity such as those with cancer, diabetes, kidney disease, AIDS and those on certain medications such as steroids for a long time. Pregnant women with the disease may experience miscarriages or pass the infection on to the newborn child.

The disease became reportable in the state of Texas in 1986 and assumed a greater public health importance and concern following multistate outbreaks in the USA between 1988 and 1990. In the United States approximately 2500 cases are reported annually with an estimated 500 deaths. In Houston about 8 cases are reported yearly based on recent surveillance records.

The bacterium responsible for the disease is called Listeria monocytogenes. The bacterium is found in soil and water, therefore vegetables can become contaminated from the soil or from manure used as fertilizer. Animals can carry the bacterium and not appear ill, thus foods from these animals such as meat and dairy products are potential sources of illness in humans if the meat is not properly cooked or the milk or cheese is unpasteurized.

To reduce the risk of Listeriosis: avoid unpasteurized soft cheeses, and cook left over foods or ready–to-eat foods, such as hot dogs until steaming hot. As always, keep uncooked meats separate from vegetables and cooked or ready-to-eat foods. Be sure to wash hands, knives and cutting boards after handling uncooked foods. Cook all-raw meats thoroughly.