Foodborne illness, often referred to as food poisoning, occurs from consuming food or beverages contaminated with harmful bacteria, viruses, parasites, or toxins. While many different germs can cause such illnesses, a specific group is responsible for a significant majority of cases, hospitalizations, and fatalities each year. These illnesses can present with a range of symptoms, often mimicking the flu, making identification challenging. Understanding these common culprits and how to prevent their spread is important for public health.
Understanding the “Big Six”
Public health organizations identify a specific group of pathogens as the “Big Six” foodborne illnesses due to their high transmissibility, severity, and impact on public health. These six are Norovirus, Salmonella (including both Nontyphoidal Salmonella and Salmonella Typhi), Clostridium perfringens, Staphylococcus aureus, Campylobacter, and Shiga toxin-producing Escherichia coli (STEC). These pathogens collectively account for a large proportion of foodborne illnesses, hospitalizations, and deaths annually. Their widespread presence necessitates focused attention on prevention and control.
Detailed Look at Each Illness
Norovirus
Norovirus is a highly contagious virus that causes acute gastroenteritis. Symptoms include sudden onset of severe vomiting, watery diarrhea, nausea, and stomach cramps, sometimes accompanied by a low-grade fever and muscle pain. Illness develops within 12 to 48 hours after exposure and resolves within one to three days. This virus spreads through contaminated food, water, surfaces, and direct person-to-person contact. Contaminated ready-to-eat foods and raw shellfish are common sources.
Salmonella
Salmonella is a bacterium that causes an infection known as salmonellosis. Individuals experience diarrhea, which can sometimes be bloody, along with fever, stomach cramps, nausea, vomiting, chills, and headaches. Symptoms appear between 6 hours and 6 days after exposure, lasting four to seven days. Common sources include raw or undercooked poultry, eggs, unpasteurized milk, and contaminated produce or water.
Clostridium perfringens
Clostridium perfringens is a bacterium that produces toxins in food, leading to sudden abdominal pain and diarrhea. Symptoms manifest within 6 to 24 hours after consuming contaminated food and resolve within 24 hours. This bacterium thrives in large quantities of food, such as meats, stews, and gravies, that are prepared in bulk and not kept at proper hot temperatures before serving.
Staphylococcus aureus
Staphylococcus aureus is a bacterium that produces toxins in food, causing rapid onset of illness. Symptoms, including severe nausea, vomiting, stomach cramps, and diarrhea, begin within 30 minutes to 8 hours after eating contaminated food. These symptoms last for one to three days. The bacteria are found on human skin and in nasal passages, with contamination occurring when food handlers touch ready-to-eat foods like sliced meats, pastries, or salads without proper handwashing.
Campylobacter
Campylobacter is a type of bacteria that causes campylobacteriosis, an infection characterized by diarrhea, which may be bloody, abdominal cramps, fever, nausea, and vomiting. Symptoms emerge within two to five days after exposure. Raw or undercooked poultry, unpasteurized milk, and contaminated water are sources of this bacterial infection.
E. coli (STEC)
Shiga toxin-producing Escherichia coli (STEC) can cause severe gastrointestinal illness. Symptoms include stomach cramps, diarrhea that is bloody, and vomiting, with little or no fever. Illness develops within 1 to 10 days of exposure. Raw or undercooked ground beef, unpasteurized milk and juices, and contaminated produce or water are sources. Some infections can lead to Hemolytic Uremic Syndrome (HUS), a serious complication affecting the kidneys, especially in young children.
Prevention Strategies
Following food safety practices reduces the risk of foodborne illnesses. These practices are categorized into four principles: Clean, Separate, Cook, and Chill.
Maintaining cleanliness involves washing hands with soap and water before, during, and after food preparation, and cleaning and sanitizing surfaces and utensils. Separating raw meats, poultry, and seafood from other foods prevents cross-contamination. Using separate cutting boards and utensils for raw and ready-to-eat foods minimizes germ transfer. Cooking foods to their proper internal temperatures, verified with a food thermometer, ensures harmful bacteria are destroyed. Chilling perishable foods by refrigerating them within two hours helps inhibit bacterial growth.
Responding to Suspected Illness
When a foodborne illness is suspected, taking appropriate action can reduce symptom severity and prevent further spread. Staying hydrated by sipping water, broth, or electrolyte solutions helps replace lost fluids and electrolytes, especially with vomiting or diarrhea.
Medical attention should be sought if symptoms are severe, such as persistent high fever, bloody diarrhea, diarrhea lasting more than three days, signs of severe dehydration (like decreased urination or dizziness), or if vomiting prevents keeping liquids down. Individuals in high-risk groups, including young children, older adults, pregnant individuals, or those with weakened immune systems, should also consult a healthcare provider. Reporting suspected foodborne illnesses to local health departments aids public health surveillance, as it helps identify outbreaks and prevent others from becoming sick.