Foodborne illness, commonly known as food poisoning, affects a significant portion of the population each year, with estimates suggesting that one in six Americans gets sick from contaminated food annually. While a typical case might involve uncomfortable gastrointestinal symptoms that resolve on their own, for certain groups, the consequences are far more severe, often leading to hospitalization or even death. Understanding which groups face the highest risk is paramount to preventing these severe outcomes and improving public health. Targeted safety measures are necessary to protect those whose bodies are least equipped to fight off infection.
Identifying the Populations at Highest Risk
Public health authorities recognize four primary groups at an increased risk for severe illness from foodborne pathogens: adults aged 65 and older, pregnant individuals, young children under the age of five, and people with compromised immune systems. For these individuals, an infection that might cause mild diarrhea in a healthy adult can quickly escalate into a life-threatening condition.
Older adults face greater risk because their immune systems and organs become less efficient at eliminating harmful germs with age. Children under five are vulnerable because their immune defenses are still developing, reducing their body’s ability to mount a strong defense. Pregnant women are also at a higher risk for certain infections, often with the potential for pathogen transmission to the fetus. The final group includes anyone whose immune system is weakened by an underlying disease or medical treatment, such as those with cancer, HIV/AIDS, or those taking immunosuppressive drugs.
Physiological Reasons for Heightened Vulnerability
The increased danger for these groups is rooted in specific biological mechanisms that undermine the body’s natural defenses. In older adults, the progressive weakening of the immune system, known as immunosenescence, plays a major role. Many seniors also experience a decrease in stomach acid production, which normally functions as a barrier by killing ingested bacteria.
Young children have an underdeveloped immune system and a less acidic stomach environment, allowing pathogens to survive and establish an infection more easily. Their developing bodies are also particularly susceptible to dehydration resulting from diarrhea, a common and dangerous complication of foodborne illness. Pregnant individuals must maintain immune tolerance to prevent rejecting the fetus, and this necessary down-regulation of the cellular immune response makes them more susceptible to certain intracellular pathogens.
For people with compromised immune systems, the underlying medical condition or treatment directly impairs the body’s ability to fight off infection effectively. Conditions like diabetes, liver disease, or treatments such as chemotherapy prevent the immune system from responding robustly enough to contain the initial infection. This failure to control the pathogen can lead to a more severe and prolonged illness, often resulting in systemic infection.
Pathogens That Pose the Greatest Danger
Certain foodborne pathogens disproportionately affect high-risk groups, leading to unique and severe complications. Listeria monocytogenes is a particular concern for pregnant women, who are estimated to be about ten times more likely to get the infection than the general population. While the mother’s symptoms may be mild, the infection can cross the placenta and lead to devastating outcomes for the fetus, including miscarriage, stillbirth, or severe illness in the newborn.
E. coli O157:H7 poses a distinct threat to young children. One out of every seven children under five diagnosed with this infection may develop Hemolytic Uremic Syndrome (HUS), a serious condition that causes acute kidney failure and can require intensive medical intervention.
For older adults and the immunocompromised, Salmonella infections present a heightened risk of developing into a severe systemic illness. Salmonella can spread from the intestines to the bloodstream, causing a severe infection that is difficult to treat. Nearly half of people aged 65 and older with a lab-confirmed Salmonella illness are hospitalized. These three pathogens—Listeria, E. coli O157:H7, and Salmonella—are responsible for a significant number of the most serious foodborne illness cases among high-risk populations.
Targeted Prevention for High-Risk Groups
Prevention for vulnerable populations must go beyond general food safety advice to include specific food avoidance and handling techniques. Individuals in high-risk categories should consistently avoid foods known to harbor serious pathogens, such as:
- Raw or unpasteurized milk and juices.
- Soft cheeses made with unpasteurized milk.
- Cold deli meats.
- Refrigerated smoked fish (unless thoroughly reheated to steaming hot).
The use of a food thermometer is an indispensable tool to ensure foods reach the safe minimum internal temperature required to kill harmful bacteria. For example, ground meats should be cooked to 160°F and all poultry to 165°F. People with severely compromised immune systems should also take extra precautions to avoid cross-contamination by keeping raw meat separate from ready-to-eat foods.