Foodborne illnesses are conditions resulting from consuming contaminated food or drink. While many types exist, some are notably more contagious than others, posing a higher risk for rapid spread within communities. These highly transmissible pathogens can turn a localized food contamination event into a broader public health concern.
The Most Contagious Culprits
Norovirus is a highly contagious foodborne illness, often responsible for widespread outbreaks. It requires only a small number of viral particles to cause infection. This virus can lead to sudden onset of vomiting and diarrhea.
Hepatitis A is another highly contagious virus that can spread through contaminated food. It causes inflammation of the liver and can be transmitted by infected food handlers.
Bacteria such as Shigella species are also highly contagious. As few as 10 to 200 bacteria can cause illness, making person-to-person transmission common. Escherichia coli O157:H7, a specific strain of E. coli, can also spread from person to person after food exposure. This bacterium produces a toxin that can lead to severe gastrointestinal symptoms, including bloody diarrhea.
Understanding Contagion: How They Spread
Highly contagious foodborne illnesses primarily spread through the fecal-oral route, meaning pathogens from an infected person’s feces are ingested by another individual. This occurs directly through person-to-person contact or indirectly via contaminated food, water, or surfaces. A low infectious dose means even a tiny amount of the pathogen, sometimes as few as 10 organisms, can cause illness.
Norovirus particles are shed in the stool and vomit of infected individuals and can remain contagious for days to weeks after symptoms resolve. These viruses also persist environmentally, surviving on surfaces for extended periods, and can become airborne through aerosolized vomit particles. Hepatitis A virus survives for several hours on hands and days on environmental surfaces. E. coli O157:H7 can also transmit person-to-person within families and institutional settings.
Stopping the Spread: Prevention Strategies
Thorough handwashing is a primary defense against contagious foodborne illnesses. Wash hands with warm, soapy water for at least 20 seconds, especially before and after handling food, after using the bathroom, and after tending to a sick person. It is particularly important for food handlers to wash hands frequently and effectively to prevent contamination.
Proper food handling and preparation practices are also important. Separate raw meats, poultry, and seafood from ready-to-eat foods to prevent cross-contamination. Cook foods to appropriate internal temperatures to eliminate harmful bacteria and viruses. Promptly refrigerate perishable foods within two hours of serving to prevent bacterial multiplication.
Cleaning and sanitizing contaminated surfaces, especially after vomiting or diarrhea, is essential. For norovirus, a solution of household bleach and water or an EPA-approved disinfectant is recommended for hard surfaces, left to sit for several minutes. For soft surfaces like bedding, machine washing with hot water and detergent is advisable. Individuals who are ill should avoid preparing food for others to prevent further transmission.
When to Be Concerned: Recognizing Symptoms and Seeking Help
Symptoms of highly contagious foodborne illnesses include nausea, vomiting, diarrhea, abdominal cramps, and fever. Onset varies, appearing hours to a few days after exposure. Most people recover within days, but certain symptoms indicate a need for medical attention.
Seek medical help if experiencing signs of dehydration, such as decreased urination, dry mouth, extreme thirst, or dizziness upon standing. Other symptoms include bloody diarrhea, diarrhea lasting over three days, a high fever (over 102°F or 38.3°C), or persistent vomiting that prevents keeping liquids down. Vulnerable populations, including infants, young children, the elderly, pregnant individuals, and those with weakened immune systems, are at higher risk for severe illness and should consult a doctor promptly if symptoms arise. Staying home from work or school, especially for those in food service or healthcare, is important to prevent further spread.