Foodborne pathogens are microorganisms that, when consumed through contaminated food or beverages, can cause illness. These illnesses range from mild discomfort to severe, life-threatening conditions, leading to millions of sicknesses, hospitalizations, and thousands of deaths globally each year. The impact extends beyond health, affecting healthcare costs and productivity. Addressing foodborne illness is a significant public health challenge, highlighting the importance of understanding the risks.
Understanding the “Big 6” Designation
A specific group of foodborne pathogens is referred to as the “Big 6” due to their significant impact on public health and food safety. These six pathogens are frequently implicated in foodborne illness outbreaks, causing widespread contamination and severe illnesses. Their commonality and potential for harm make them a focus for regulatory efforts and food worker guidelines.
Key Characteristics of Each Pathogen
Salmonella
Salmonella is a bacterium commonly found in raw or undercooked poultry, eggs, and various meats such as beef and pork. It can also contaminate unpasteurized milk, produce, and even processed foods. Symptoms of Salmonella infection typically include diarrhea, which can sometimes be bloody, along with fever, stomach cramps, nausea, vomiting, and headache. Illness generally begins 6 hours to 6 days after exposure and usually resolves within 4 to 7 days.
Shigella
Shigella bacteria are primarily spread through contaminated food or water, often due to human waste or unsanitary handling by food workers. Common food sources include salads (such as potato, tuna, macaroni, and chicken), raw vegetables, milk, dairy products, and poultry. Individuals infected with Shigella typically experience diarrhea, which may be watery or bloody and can contain mucus. Other symptoms include fever, nausea, vomiting, and abdominal cramps. Symptoms usually appear 1 to 2 days after exposure and can last for 5 to 7 days.
Shiga Toxin-Producing Escherichia coli (STEC)
Shiga toxin-producing Escherichia coli (STEC), particularly the O157:H7 strain, is a bacterium that can cause severe illness. Common sources include raw or undercooked ground beef, unpasteurized milk and juices, and contaminated produce. Infection often leads to severe abdominal cramps, diarrhea that is frequently bloody, and sometimes vomiting with a mild fever. In some cases, STEC can cause hemolytic uremic syndrome (HUS), a serious complication affecting the kidneys.
Campylobacter jejuni
Campylobacter jejuni is a common bacterial cause of diarrheal illness, frequently found in the intestines of poultry and other animals. Humans typically contract this infection from consuming raw or undercooked poultry, unpasteurized milk, contaminated water, or raw vegetables and shellfish. Symptoms include diarrhea, often bloody or watery, accompanied by abdominal pain, fever, and nausea. Vomiting is less common, and in some instances, infection can lead to Guillain-Barré syndrome.
Clostridium perfringens
Clostridium perfringens is a bacterium often associated with foods cooked in large batches and then held at unsafe temperatures, such as meats, poultry, and gravies. This bacterium produces toxins when consumed, leading to illness. The primary symptoms are watery diarrhea and stomach cramps, typically appearing 6 to 24 hours after eating contaminated food. Unlike many other foodborne illnesses, Clostridium perfringens infection usually does not cause fever or vomiting and generally resolves within 24 hours.
Staphylococcus aureus
Staphylococcus aureus is a bacterium that can produce toxins in food, even if the food appears normal. Foods commonly implicated include meats, poultry, egg products, salads (like egg, tuna, and macaroni salads), bakery items such as cream-filled pastries, and sandwich fillings. Contamination often occurs through food handlers and is more likely when foods are handled extensively and then left at room temperature. Symptoms develop rapidly, often within 30 minutes to 6 hours, and include nausea, violent vomiting, and abdominal cramping, sometimes with diarrhea. Fever is typically absent, and the illness usually resolves within a few days.
Preventing Illness from These Pathogens
Preventing illness from foodborne pathogens involves consistent application of fundamental food safety practices. Thorough handwashing is a primary defense, requiring scrubbing with soap and water for at least 20 seconds before, during, and after food preparation, especially after handling raw meats or using the restroom. This practice significantly reduces the transfer of harmful bacteria.
Avoiding cross-contamination is another important step to keep food safe. Raw meats, poultry, and seafood should be kept separate from other foods, particularly ready-to-eat items, during shopping, storage, and preparation. Using separate cutting boards and utensils for raw and cooked foods, or thoroughly washing them between uses, prevents the spread of bacteria.
Cooking foods to the correct internal temperatures is important for eliminating pathogens. Use a food thermometer to ensure meats and poultry reach safe temperatures, as visual cues are unreliable. For example, poultry should reach 165°F.
Proper chilling and refrigeration slow bacterial growth. Perishable foods should be refrigerated promptly, ideally within two hours of cooking or purchase, or within one hour if temperatures are above 90°F. Maintain refrigerator temperatures at 40°F (4°C) or below, and cool hot foods rapidly before refrigeration. Avoiding unpasteurized products, such as milk or juices, also reduces exposure.