Who is most at risk for becoming ill with Listeria?
The elderly, pregnant women and anyone immunocompromised is most at risk for contracting Listeria.
Several segments of the population are at increased risk and need to be informed so that proper precautions can be taken. [19,20, 27] The body’s defense against Listeria is called “cell-mediated immunity” because the success of defending against infection depends on our cells (as opposed to our antibodies), especially lymphocytes called “T-cells.”  Therefore, individuals whose cell-mediated immunity is suppressed are more susceptible to the devastating effects of listeriosis, including especially HIV-infected individuals, who have been found to have a Listeria-related mortality of 29%. [12, 17, 18]
Pregnant women naturally have a depressed cell-mediated immune system. [18, 24] In addition, the immune systems of fetuses and newborns are very immature and are extremely susceptible to these types of infections.  Other adults, especially transplant recipients and lymphoma patients, are given necessary therapies with the specific intent of depressing T-cells, and these individuals become especially susceptible to Listeria as well. [7, 18, 27]
According to the CDC and other public health organizations, individuals at increased risk for being infected and becoming seriously ill with Listeria include the following groups:
- Pregnant women: They are about 20 times more likely than other healthy adults to get listeriosis. About one-third of listeriosis cases happen during pregnancy.
- Newborns: Newborns rather than the pregnant women themselves suffer the serious effects of infection in pregnancy.
- Persons with weakened immune systems
- Persons with cancer, diabetes, or kidney disease
- Persons with AIDS: They are almost 300 times more likely to get listeriosis than people with normal immune systems.
- Persons who take glucocorticosteroid medications (such as cortisone)
- The elderly [11, 20, 21]