Listeriosis is rare but disproportionately dangerous. Around 1,250 cases occur annually in the United States, with roughly 800 of those confirmed through laboratory testing and reported to the CDC. Globally, the rate falls between 0.1 and 10 cases per million people per year, depending on the country. Those numbers make it one of the least common foodborne illnesses, yet it carries one of the highest death rates of any food-related infection.
How It Compares to Other Foodborne Illnesses
To put listeria in perspective, salmonella causes an estimated 1.35 million infections per year in the U.S. Listeria’s roughly 1,250 cases barely register by comparison. But frequency and severity are two different things. Over 95% of people diagnosed with invasive listeriosis end up hospitalized, and 15 to 20% die. That fatality rate makes it one of the deadliest foodborne diseases, even though most people will never encounter it.
The economic toll reflects that severity. Foodborne listeria infections cost an estimated $2.8 billion annually in the U.S. when you factor in medical expenses, lost wages, and the broader societal cost of deaths. That ranks it third among all foodborne pathogens in economic burden, despite being far less common than most of them.
Who Gets Listeria
Listeria doesn’t hit everyone equally. Three groups face the highest risk: pregnant women, adults over 65, and people with weakened immune systems from conditions like cancer, diabetes, liver disease, or organ transplants.
Pregnant women are 18 times more likely to develop listeriosis than the general population, with an incidence of about 12 cases per 100,000 compared to 0.7 per 100,000 in non-pregnant adults. The infection often causes mild flu-like symptoms in the mother, but the consequences for the pregnancy can be severe. Spontaneous abortion occurs in 10 to 20% of cases, roughly half of affected pregnancies deliver preterm, and intrauterine fetal death happens in about 11%.
Adults aged 65 and older have an incidence of about 1.3 cases per 100,000, nearly double the rate in the general population. As immune function naturally declines with age, the body becomes less effective at fighting off the bacterium before it can cause serious illness.
Many People Carry Listeria Without Knowing
Here’s something that may surprise you: listeria lives in the digestive tracts of healthy people more often than the case numbers suggest. One large study of 900 healthy, asymptomatic donors found the bacterium in 10% of stool samples. Most estimates of fecal carriage in the general population land below 1%, but newer detection methods that look for genetic material rather than live cultures tend to find higher rates.
This means that exposure to listeria is far more common than actual illness. A healthy immune system typically clears the bacterium before it causes problems. It’s when the bacterium crosses from the gut into the bloodstream or nervous system that serious disease develops, and that progression is largely limited to people in those high-risk groups.
What Symptoms Look Like and When They Appear
Listeria has two distinct forms, and the timeline differs dramatically between them. The milder form, gastroenteritis, shows up fast. Symptoms like diarrhea, fever, and muscle aches typically start within about 24 hours of eating contaminated food, though the range spans 6 hours to 10 days.
Invasive listeriosis takes much longer. The overall median incubation period is 8 days, but the range stretches from 1 to 67 days. That wide window makes it notoriously difficult to trace back to a specific meal. The timeline also varies by how the infection presents. Bloodstream infections tend to appear within a couple of days, while infections that reach the brain and spinal cord take a median of 9 days. Pregnancy-associated cases have the longest delay, with a median of 27.5 days between exposure and symptoms.
Which Foods Are Most Often Linked
Listeria outbreaks have been traced to a wide variety of foods in recent years. Deli meats and ready-to-eat products are repeat offenders, appearing in multiple outbreak investigations in 2024 and 2025 alone. Soft cheeses like brie, camembert, queso fresco, and cotija have also been implicated. But the list extends well beyond the traditional warnings about lunch meat and unpasteurized cheese.
Recent outbreaks have been linked to leafy greens, enoki mushrooms, peaches, nectarines, plums, ice cream, supplement shakes, and prepared pasta meals. The common thread isn’t a single food category. It’s that listeria thrives in refrigerated, ready-to-eat products. Unlike most bacteria, it grows at refrigerator temperatures, which means contaminated food that sits in your fridge for days can become more dangerous over time rather than staying stable.
Why Case Counts Are Hard to Pin Down
The gap between the 800 reported cases and the estimated 1,250 total cases reflects a basic reality of disease surveillance: not every case gets diagnosed. Some people with mild symptoms never see a doctor. Others are tested using newer diagnostic methods that detect bacterial DNA rather than growing the organism in a lab. These culture-independent tests are more sensitive, meaning they’re better at catching infections, but they create a tradeoff. Without a live bacterial sample, public health labs can’t determine the strain’s genetic fingerprint or connect cases to a common outbreak source.
This shift in testing technology also makes it harder to tell whether listeria rates are truly changing over time or whether surveillance is simply picking up cases that would have gone undetected a decade ago. The CDC has acknowledged that interpreting trends in incidence has become more complicated as these newer tests become standard practice in hospitals.