Listeriosis is a form of bacterial infection caused by Listeria monocytogenes, The severity of this condition ranges from minor flu-like symptoms to death. The bacteria can attack the central nervous system, causing a variety of neurological problems, including meningitis, seizures and loss of certain brain functions. In addition, individuals with a weak immune system are susceptible to systemic problems. Normal individuals often experience digestive problems or stomach pain. Individuals may contract this infection from eating contaminated food; the bacteria enters other organ systems by passing through the intestinal walls. Doctors diagnose this disease through blood and cerebrospinal fluid examinations. Treatment depends on the severity of the infection. Doctors often provide patients with long-term doses of antibiotics, primarily ampicillin and gentamicin, to rid the body of the bacteria.