Infectious agent: Listeria monocytogenes, a gram-positive rod-shaped bacterium
Description of illness: The bacterium Listeria monocytogenes causes listeriosis, a rare but serious foodborne disease. It primarily affects older adults, pregnant women, infants and those with weakened immune systems. Older and immunocompromised adults often experience septicemia and meningitis, while pregnant women experience fever, fatigue and muscle aches. Infection of pregnant women can lead to fetal loss or life-threatening infections in newborns.