Food Borne Diseases
A brief introduction
Photo credit: kaibara87 on Flickr
Did you know that there are more than 600 food-borne diseases known today? With so many pathogens out there, food poisoning is one of the most common infections. In fact, one in every six Americans suffer from food-borne illness every year.
Food poisoning is defined as serious injury resulting from food. Its chief mainfestation is gastroenteritis, or irritation and inflammation of the G.I. tract. The main symptoms, as many of us are unfortunately aware, are abdominal pain, diarrhea, and vomiting. High fevers, internal bleeding, and secondary illnesses can result from food poisoning. Some food-borne diseases are very dangerous and are even fatal. Because food-borne diseases are so widespread and often serious, it is important that we eaters be well-informed.
Food-borne illnesses are usually caused by a toxin, a poison produced by a living cell, or pathogen, a microorganism that produces sickness. Food-borne diseases include allergic reactions to food, e.g. gluten, and any other condition in which food is the carrier of infection or toxin, e.g., botulism.
The most frequent kind of food-borne disease
Campylobacter Photo credit: AJC1, on Flickr
Infections are the most common and, probably, the most well-known kind of food-borne illness. They happen when there are enough disease-causing organisms, like salmonella, to colonize in the gut and cause symptoms. Microorganisms that cause infections are very hearty: they have to survive all the digestive enzymes, including the ones that break down proteins, and the high acidity of the stomach before they even begin to colonize.
Here are the six most common infectious microorganisms and the foods they are most likely to be found in: 
- Norovirus (the leading cause of food poisoning in the US with over 5 million people infected yearly) - leafy greens, fresh fruits, and shellfish.
- Salmonella - eggs, poultry, and contaminated raw vegetables and fruits
- Shigella - improperly handled ready-to-eat food, like sandwiches and salads
- Campylobacter - raw or undercooked poultry or meat
- Listeria - soft cheeses, unpasteurized milk, deli meats, hot dogs
- Toxoplasmosis (a parasite that is the leading cause of death from food-borne illness in the US) - undercooked meat and cross-contamination from cat feces
Not just from microorganisms
Intoxications are caused by ingesting toxins, whether they are biological, like botulism, mineral, like arsenic, or chemical, like pesticides. The most common toxins come from microorganisms as a normal byproduct of the microorganism's metabolism. For instance, the botulism toxin is naturally produced by Clostridium botulinum bacteria, is extremely heat-resistant and can lie dormant for years. Botulism is a neurotoxin and is most dangerous for infants. Fortunately, intoxications make up only a minor percentage of food-borne disease. Even though toxins are often found in chemicals and pesticides, contrary to popular belief, they are numerically the least important kind of food poisoning.
Staphylococcus aureus Photo credit: adonofrio on Flickr
One of the most important toxin-producing microorganisms is staphylococal bacteria. Staphylococal aureus is heat-resistant and can't be destroyed by cooking. It causes nausea, stomach cramps, vomiting, and diarrhea. Staph intoxications are fast-acting compared and can show symptoms in as little as 30 minutes after eating. They most likely culprits are sliced meat, pastries, and sandwiches. The CDC estimates that it affects 3% of people in the US.
Most serious kind of food poisoning
Toxicoinfections first infect the G.I. tract, then the organisms produce the toxins. What's the difference between toxicoinfections and intoxications? The toxins are produced in the gut rather than in food. These are the most serious type of food-borne disease, because the toxin is continually produced in the infected person.
E. coli Photo credit: adonofrio on Flickr
Escherichia coli is the most well-known of the toxicoinfectious agents. Most E. coli, including the ones that normally live in the human gut, are harmless. However, there are several strains that can be extremely dangerous. E. coli 0157 made the news in the late 1980s when a young boy died as a result of eating undercooked beef. In June 2011, a rare form of E.coli (STEC 0104:H4) which produces Shiga toxin caused an outbreak in hundreds of people in Germany. It resulted in kidney problems and hemorrhaging. Since E. coli, as well as many other food-borne pathogens, can be spread from person-to-person, the best protection is thorough hand-washing.
Vibrio cholarae is another common toxicoinectious agent. It produces extremely watery diarrhea and severe dehydration, which can quickly lead to death. Vibrio is most commonly found in fish and shellfish. The best protection is to avoid eating raw or undercooked seafood and shellfish.