Food borne pathogens (bacteria, viruses and parasites) are the leading cause of gastrointestinal illness in the US. Most cases involve a day or two of nausea, vomiting, diarrhea and abdominal pain. These symptoms are unpleasant to be sure, but rarely serious. Other cases, depending on the type of organism and the person's state of health, can be deadly.

Michelle Triche, LDN, RD, MHA, a licensed dietitian and the director of East Jefferson General Hospital's Food & Nutrition Services, is an expert on food safety. She has to be - her team serves nearly 2,500 meals a day to patients, visitors, and employees. Many of the hospital's patients have compromised immune systems, meaning they aren't as able to fight off infection as healthy individuals. For them, exposure to a food borne bacteria or virus could be deadly.

"Food safety is important everywhere," says Michelle. "But it's ten times as important here at the hospital."

Above all, Michelle says, hand washing is the most important element of safe food handling. Hands should be washed before food preparation begins and after handling raw meat, poultry or seafood. This will prevent cross contamination, or transferring an organism from one food to another. For example, raw chicken may contain salmonella, bacteria that can cause illness. Salmonella is killed by cooking the chicken. However, if you handle the raw chicken then tear lettuce for a salad without washing your hands, you may transfer salmonella bacteria from the chicken to the lettuce. The lettuce won't be cooked, so the bacteria won't be killed.

Cross contamination can also occur if utensils and cutting boards aren't handled properly. Cutting boards used for raw meat, poultry or fish should be washed with hot, soapy water before they are used for another food. The same is true for knives, forks, spoons, plates or bowls that come into contact with uncooked meats. Vegetables that won't be cooked, like salad vegetables, should be washed with soap and water before they are consumed.

According to Michelle, temperature is another important element in preventing food borne illness. She describes the 'danger zone,' from 40º to 140º F. This is the temperature range in which bacteria is most likely to grow in food. Once the bacteria start to grow, they multiply exponentially. Food that stays in the danger zone for more than two hours, including thawing and preparation time, is no longer safe to eat.

Improper thawing is a common mistake that people make in their kitchens. Many people place foods on the kitchen counter to thaw at room temperature. This leaves food in the danger zone for a potentially long period of time. There are three ways to safely thaw food: in the refrigerator, in the microwave, or under water that is at less than 70ºF.

When the food is cooked, it is important to make sure that it reaches the proper internal temperature (see table on page 9). Confirm the temperature with a meat thermometer that is calibrated properly to ensure accuracy. Cooked food should not be allowed to sit at room temperature, but should be refrigerated as soon as possible to keep it out of the danger zone. When cooling a large container of hot food, a big pot of gumbo for example, Michelle advises dividing it into smaller containers to help it cool faster.

Another potential avenue for bacteria growth is keeping leftovers too long. At EJGH, if leftover food is not used the following day, it is discarded. Once bacteria have begun to grow in cooked food, contamination is not eliminated by reheating. Bacteria leave behind toxins that are not affected by heat and can cause serious illness. When foods are reheated, they should be brought to 165ºF to ensure safety. It's also important to remember that contaminated food may not have an odor, so don't rely on your sense of smell to determine if food is safe to eat.

Discarding food after one day may seem wasteful, but it helps to ensure that the food is safe to eat. If you always seem to have leftovers, consider preparing smaller portions so you won't have more than you need. The upside of cooking smaller amounts more often is that your meals will taste better.

"Foods always taste better if they're fresh," says Michelle.

Michelle also has advice for keeping food in your cupboards. She says the best way to store food is 'first in, first out.' Place your most recently purchased non-perishable food in the back of the cupboard and bring the rest forward so forgotten canned goods don't spend decades in your pantry. If a can looks swollen, throw it out. This is a sure sign of contamination. Dented cans are also a no-no. Cans have a protective seal coating their insides, which can be broken if the can is dented. Once the food inside is exposed to the metal of the can, it can become contaminated.

Most Unwanted Bacteria and Viruses

Most Unwanted for Causing Gastroenteritis, Wound Infections and Septicemia

Vibrio vulnificus
Type of Microorganism: Bacteria
Known Hideouts: Found in all coastal waters in the US. It is also found in raw and recontaminated shellfish, including oysters, clams and crabs.
Modus Operandi: Causes gastroenteritis (nausea, vomiting and diarrhea) if consumed. Wound infections occur when cuts are exposed to contaminated seawater. Those with compromised immune systems and those with chronic liver disease are at increased risk of septicemia, a bloodstream infection that can cause septic shock and death. Death occurs in up to 50% of cases of septicemia caused by Vibrio vulnificus.
The most common source of infection by Vibrio vulnificus is eating raw oysters.

Most Unwanted for causing Salmonellosis and Typhoid Fever

Salmonella
Type of Microorganism: Bacteria
Known Hideouts: Raw meat, poultry, eggs, milk, fish, and shrimp. Often found in sauces and salad dressings made with raw eggs, including hollandaise sauce and Caesar dressing.
Modus Operandi: Causes nausea, vomiting, abdominal cramps, diarrhea, fever and headache. In extreme cases, salmonellosis can cause septicemia, an infection that can damage virtually every organ system. The elderly and anyone with a compromised immune system are at highest risk for complications. As few as 15 to 20 cells are enough to cause an infection.
There are 40,000 to 50,000 reported cases of salmonellosis each year in the US.

Most Unwanted for causing Foodborne Botulism

Clostridium botulinum
Type of Microorganism: Bacteria
Known Hideouts: Inadequately processed home-canned foods, particularly vegetables with low acidity like green beans, corn and asparagus. It may also be found in baked potatoes that are cooked in aluminum foil if they are not eaten while hot or refrigerated promptly.
Modus Operandi: Clostridium botulinum produces a neurotoxin that causes muscle paralysis. Initial symptoms of exposure may include blurry vision, slurred speech, drooping eyelids and difficulty swallowing. The paralysis can progress to the arms, legs and trunk, starting with the shoulders and descending down the body. It can be fatal if the muscles used to breathe become paralyzed.
Boiling home-canned foods for 10 minutes will prevent contamination with Clostridium botulinum.

Most Unwanted for causing Viral Gastroenteritis

Norwalk Virus
Type of Microorganism: Virus
Known Hideouts: Shellfish and salad ingredients contaminated by ill food handlers may harbor the virus. Raw or insufficiently steamed clams and
oysters are also a source of infection.
Modus Operandi: Infection is self-limiting (resolves without medical treatment) and causes nausea, vomiting, diarrhea, abdominal pain, and sometimes headache or low-grade fever.
Norwalk virus became newsworthy after causing illness among passengers on several cruise ships.