listeriosis

Listeriosis is an infection caused by the bacterium Listeria monocytogenes. It is mainly foodborne and can cause mild gastrointestinal illness in healthy adults, but it poses a greater risk for invasive disease in older adults, pregnant women and their fetuses, newborns, and people with weakened immune systems. Listeria can multiply at refrigeration temperatures, allowing certain foods to become vehicles for transmission.

Most cases result from eating contaminated foods, such as unpasteurized dairy products, soft cheeses made from unpasteurized milk, deli meats and hot dogs, smoked fish, refrigerated pâtés, and some raw vegetables. The incubation period ranges from about 3 to 70 days. Pregnant women are at particular risk for fetal loss, preterm birth, or neonatal infection, which may include meningitis in newborns.

Clinical presentation varies. Invasive disease can cause fever, malaise, and sometimes gastrointestinal symptoms, followed by bacteremia or meningitis. In pregnant women, infection can be asymptomatic or present with flu-like symptoms but may lead to fetal complications. Diagnosis relies on culture of Listeria from blood, CSF, or amniotic fluid, supported by PCR in some settings. Imaging assists in meningitis or focal infection.

Treatment depends on disease severity. Invasive listeriosis is treated with antibiotics such as ampicillin, often combined with gentamicin; alternatives include penicillin in penicillin-allergic patients or trimethoprim-sulfamethoxazole. Prevention focuses on food safety: heat ready-to-eat foods until steaming, avoid unpasteurized dairy products, thoroughly cook meats, refrigerate promptly, and practice good kitchen hygiene. Public health measures monitor outbreaks and issue recalls when contamination is identified.