Listeria outbreak: What is listeriosis and how is it treated?

Newswise — A recent recall of more than 7 million pounds of deli meat has marked the largest listeria outbreak since 2011, according to the Center for Disease Control and Prevention. The outbreak has been traced to a Boar’s Head meat plant in Virginia, leading to the hospitalization of nearly 60 people who consumed contaminated products.

Brenda Wilson, professor of microbiology and adjunct professor of pathobiology at the University of Illinois Urbana-Champaign, studies the molecular interactions and biochemical mechanisms by which protein toxins produced by pathogenic bacteria cause their toxic effects on animal cells. She is the author of the book Revenge of the Microbes. Wilson is available to provide insight into the spread of literia and ways to combat potential infection. 

What is listeriosis?

Listeriosis is a potentially lethal foodborne disease caused by infection with a bacterium called Listeria, which is naturally found in soil, water, sewage, and plants. It can contaminate food and food processing facilities, including refrigeration units where food is stored. This bacterium is very hardy and can grow readily at refrigerator temperatures (4℃/39.2℉) as well as at body temperature (37℃/98.6℉).

Who is most at risk from a listeria infection?

This bacterium can invade cells and spread throughout the body, especially if the person is immune compromised. It can travel from one cell to another without exposing itself to the immune cells or antibodies. In individuals with healthy immune systems, symptoms are usually mild and self-limiting intestinal gastroenteritis. Serious illness including sepsis, meningitis, and encephalitis can occur in pregnant women, newborn or young children, adults with weakened immunity, and the elderly. 

Is listeria contagious?

No, listeriosis is not spread from person to person. Transmission is primary foodborne through contaminated food, with the exception of pregnant women who can transmit the bacteria to their fetus through placental penetration. 

Can a listeria infection be treated? How?

Yes, usually through intravenous administration of high-dose antibiotics like ampicillin, penicillin, or amoxicillin. To accommodate penicillin allergies, fluoroquinolones may be given instead. 

How can an individual reduce the risk of contracting listeria?

Listeria bacteria can be killed by pasteurization and adequate cooking — at least 73℃/165℉. Using pasteurized milk and dairy products is highly advised. Storage of food at temperatures below 4℃/39℉ reduces bacterial growth, but adequate cooking of meat is strongly recommended, especially for the at-risk populations mentioned above. Effective prevention also requires appropriate hygiene practices and sanitation of food processing, preparation, and cooking surfaces.