Foodborne Illness
Food-borne illness can cause a variety of symptoms ranging from nausea and stomach ache to vomiting and diarrhea, possibly a fever and fatigue. The bacteria or viruses that can cause food-borne illness can come from a variety of sources. This may include the existing environment, the food item itself, or from an ill food-handler.
How does food become contaminated?
We live in a microbial world, and there are many opportunities for food to become contaminated as it is produced and prepared. Many foodborne microbes are present in healthy animals (usually in their intestines) raised for food. Meat and poultry carcasses can become contaminated during slaughter by contact with small amounts of intestinal contents. Similarly, fresh fruits and vegetables can be contaminated if they are washed or irrigated with water that is contaminated with animal manure or human sewage. Some types of Salmonella can infect a hen’s ovary so that the internal contents of a normal looking egg can be contaminated with Salmonella even before the shell in formed. Oysters and other filter feeding shellfish can concentrate Vibrio bacteria that are naturally present in sea water, or other microbes that are present in human sewage dumped into the sea.
Later in food processing, other foodborne microbes can be introduced from infected humans who handle the food, or by cross contamination from some other raw agricultural product. For example, Shigella bacteria, hepatitis A virus and Norwalk virus can be introduced by the unwashed hands of food handlers who are themselves infected. In the kitchen, microbes can be transferred from one food to another food by using the same knife, cutting board or other utensil to prepare both without washing the surface or utensil in between. A food that is fully cooked can become recontaminated if it touches other raw foods or drippings from raw foods that contain pathogens.
The way that food is handled after it is contaminated can also make a difference in whether or not an outbreak occurs. Many bacterial microbes need to multiply to a larger number before enough are present in food to cause disease. Given warm moist conditions and an ample supply of nutrients, one bacterium that reproduces by dividing itself every half hour can produce 17 million progeny in 12 hours. As a result, lightly contaminated food left out overnight can be highly infectious by the next day. If the food were refrigerated promptly, the bacteria would not multiply at all. In general, refrigeration or freezing prevents virtually all bacteria from growing but generally preserves them in a state of suspended animation. This general rule has a few surprising exceptions. Two foodborne bacteria, Listeria monocytogenes and Yersinia enterocolitica can actually grow at refrigerator temperatures. High salt, high sugar or high acid levels keep bacteria from growing, which is why salted meats, jam, and pickled vegetables are traditional preserved foods.
Microbes are killed by heat. If food is heated to an internal temperature above 160oF, or 78oC, for even a few seconds this sufficient to kill parasites, viruses or bacteria, except for the Clostridium bacteria, which produce a heat-resistant form called a spore. Clostridium spores are killed only at temperatures above boiling. This is why canned foods must be cooked to a high temperature under pressure as part of the canning process.
The toxins produced by bacteria vary in their sensitivity to heat. The staphylococcal toxin which causes vomiting is not inactivated even if it is boiled. Fortunately, the potent toxin that causes botulism is completely inactivated by boiling.
Incubation period
How soon the symptoms of a food-borne illness appear after eating a suspect food depends largely on what type of bacteria, virus, parasite, or even chemical contamination is responsible for the symptoms. This is called the incubation period. Most commonly, the usual range is from ½ hour to 72 hours. Some common bacteria infections however, may have longer incubation periods. Chemical contaminations will typically have a significantly shorter incubation period. Therefore, the old adages –“It takes 24 hours to develop a food-borne illness” or “It had to be the very last thing I ate” are not always accurate. Simply, put…it’s NOT so simple! The pathogen or contamination, the symptoms of illness, the types of foods eaten, the incubation period, how much was consumed, age/health of the individual, etc…all can play a role.
What can consumers do to protect themselves from foodborne illness?
A few simple precautions can reduce the risk of foodborne diseases:
COOK meat, poultry and eggs thoroughly. Using a thermometer to measure the internal temperature of meat is a good way to be sure that it is cooked sufficiently to kill bacteria. For example, ground beef should be cooked to an internal temperature of 160o F. Eggs should be cooked until the yolk is firm.
SEPARATE: Don’t cross-contaminate one food with another. Avoid cross-contaminating foods by washing hands, utensils, and cutting boards after they have been in contact with raw meat or poultry and before they touch another food. Put cooked meat on a clean platter, rather back on one that held the raw meat.
CHILL: Refrigerate leftovers promptly. Bacteria can grow quickly at room temperature, so refrigerate leftover foods if they are not going to be eaten within 4 hours. Large volumes of food will cool more quickly if they are divided into several shallow containers for refrigeration.
CLEAN: Wash produce. Rinse fresh fruits and vegetables in running tap water to remove visible dirt and grime. Remove and discard the outermost leaves of a head of lettuce or cabbage. Because bacteria can grow well on the cut surface of fruit or vegetable, be careful not to contaminate these foods while slicing them up on the cutting board, and avoid leaving cut produce at room temperature for many hours. Don’t be a source of foodborne illness yourself. Wash your hands with soap and water before preparing food. Avoid preparing food for others if you yourself have a diarrheal illness. Changing a baby’s diaper while preparing food is a bad idea that can easily spread illness.
REPORT: Report suspected foodborne illnesses to your local health department. The local public health department is an important part of the food safety system. Often calls from concerned citizens are how outbreaks are first detected. If a public health official contacts you to find our more about an illness you had, your cooperation is important. In public health investigations, it can be as important to talk to healthy people as to ill people. Your cooperation may be needed even if you are not ill.
What to do if you suspect a foodborne illness
First, call your physician if it is an emergency.
Self-Care at Home
Short episodes of vomiting and small amounts of diarrhea lasting less than 24 hours can usually be cared for at home.
• Do not eat solid food while nauseous or vomiting but drink plenty of fluids.
o Small, frequent sips of clear liquids (those you can see through) are the best way to stay hydrated.
o Avoid alcoholic, caffeinated, or sugary drinks. Over-the-counter rehydration products made for children such as Pedialyte and Rehydralyte are expensive but good to use if available.
o Sports drinks such as Gatorade and Powerade are fine for adults if they are diluted with water because at full strength they contain too much sugar, which can worsen diarrhea.
• After successfully tolerating fluids, eating should begin slowly, when nausea and vomiting have stopped. Plain foods that are easy on the stomach should be started in small amounts. Consider eating rice, wheat, breads, potatoes, low-sugar cereals, lean meats, and chicken (not fried) to start. Milk can be given safely, although some people may experience additional stomach upset due to lactose intolerance.
• Most food poisonings do not require the use of over-the-counter medicines to stop diarrhea, but they are generally safe if used as directed. It is not recommended that these medications be given to children. If there is a question or concern, you should always check with a doctor.
Credits:
accessKent | Foodborne Illness
Disease Listing, Foodborne Illness, General Information | CDC Bacterial, Mycotic Diseases
Food Poisoning Causes, Symptoms, Diagnosis, and Treatment on eMedicineHealth.com.
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