Food poisoning, also called foodborne illness, is caused by eating or drinking contaminated food or drinks. Symptoms of food poisoning vary but can include nausea, vomiting, diarrhea, and abdominal cramps. Some people also develop a fever.

Of an estimated 48 million people who become sick from foodborne illnesses each year in the United States, 3,000 will die, according to the Centers for Disease Control and Prevention (CDC).

Symptoms can develop within hours or days of eating contaminated food.

Food poisoning that is caused by certain bacteria, viruses, or parasites is contagious. So, if you or your child has symptoms of food poisoning, take steps to protect yourself and to prevent the spread of the illness.

Sometimes, food poisoning is the result of chemicals or toxins found in the food. This type of food poisoning isn’t considered to be an infection, so it isn’t contagious and doesn’t spread from person to person.

There are over 250 different types of foodborne illnesses. Most of these illnesses are caused by one of the following.

1. Bacteria

Bacteria — which are tiny organisms — can get into the gastrointestinal (GI) tract through contaminated food and bring on symptoms like nausea, vomiting, diarrhea, and abdominal pain.

Bacteria can contaminate food in a number of ways:

  • You may purchase food that’s already spoiled or contaminated with bacteria.
  • Your food may become contaminated at some point during storage or preparation.

This can happen if you don’t wash your hands before preparing or handling food. It can also happen when food comes in contact with a surface contaminated with bacteria.

Improper storage of food, such as keeping food at room temperature or outdoors for too long, can also cause bacteria to grow and multiply rapidly.

It’s important to refrigerate or freeze food after cooking. Don’t eat food that’s been left sitting out for too long. Keep in mind that contaminated food may taste and smell normal.

Bacteria that can cause food poisoning include:

2. Viruses

Food poisoning caused by viruses can also pass from person to person. A common foodborne virus is norovirus, which causes inflammation in the stomach and intestines.

Hepatitis A is another foodborne illness from a virus. This highly contagious acute liver infection causes inflammation of the liver. Hepatitis A virus can be found in the stool and blood of people who are infected.

If you don’t wash your hands after using the bathroom, it’s possible to pass the virus to others through handshakes and other physical contact. You may also spread the virus to others if you prepare food or drinks with contaminated hands.

Contagious foodborne viruses also spread through indirect contact. Throughout the course of a day, you may touch several surfaces with contaminated hands. These include light switches, counters, phones, and door handles. Anyone who touches these surfaces may become ill if they put their hands near their mouth.

Bacteria and viruses can live outside the body on hard surfaces for hours, and sometimes days. Salmonella and campylobacter can live on surfaces for up to four hours, whereas the norovirus can survive on surfaces for weeks.

3. Parasites

Parasites that can cause food poisoning include:

  • Giardia duodenalis (formerly known as G. lamblia)
  • Cryptosporidium parvum
  • Cyclospora cayetanensis
  • Toxoplasma gondii
  • Trichinella spiralis
  • Taenia saginata
  • Taenia solium

Parasites are organisms that range in size. Some are microscopic, but others, such as parasite worms, may be visible to the naked eye. These organisms live in or on other organisms (called a host) and receive nutrients from this host.

When present, these organisms are found usually in the stool of humans and animals. They can transfer into your body when you eat contaminated food, drink contaminated water, or put anything in your mouth that’s come in contact with the feces of an infected person or animal.

You can spread this type of food poisoning through physical contact or by preparing food with contaminated hands.

Anyone can get food poisoning, but there are ways to prevent its spread once you’ve been infected.

Preventing the spread of contagious foodborne illnesses is important because complications can arise.

Since food poisoning can cause vomiting and diarrhea, there’s the risk of dehydration. In severe cases of dehydration, hospitalization is required to replace lost fluids. Dehydration can be particularly dangerous for infants, elderly people, and people who have a weak immune system.

Here are a few tips to prevent the spread of food poisoning once you’re already sick.

Bacteria

  • Stay home from school or work until symptoms disappear
  • Wash your hands with warm, soapy water after going to the bathroom and after coming in contact with animal or human feces.
  • Don’t prepare or handle food or drinks until symptoms disappear and you feel better.
  • Teach children how to properly wash their hands. According to the CDC, proper hand washing should take about 20 seconds, the same length of time it takes to sing the “Happy Birthday” song twice.
  • Disinfect commonly touched surfaces in the home — light switches, door knobs, countertops, remote controls, etc.
  • Clean the bathroom toilet after each use, using disinfecting wipes or a disinfectant spray on the seat and handle.
  • Virus

    • Stay home from school and work until symptoms disappear and avoid travel.
    • Wash your hands with warm, soapy water after using the bathroom and after coming in contact with human or animal feces.
    • Don’t prepare or handle food or drinks until symptoms disappear and you feel better.
    • Disinfect surfaces around the house.
    • Wear gloves when cleaning up the vomit or diarrhea of an infected person.

    Parasite

    • Wash hands with warm, soapy water after going to the bathroom and after coming in contact with human or animal feces
    • Don’t prepare or handle food or drinks until symptoms disappear and you feel better.
    • Practice safe sex. Some parasites (Giardia) can spread through unprotected oral-anal sex.

Food poisoning can cause a variety of uncomfortable symptoms such as diarrhea, vomiting, stomach pain, and a fever. However, symptoms typically resolve on their own within hours to days and don’t usually require a doctor.

Getting plenty of rest and drinking fluids can help you feel better. Even though you may not feel like eating, your body needs energy, so it’s important to nibble on bland foods like crackers, toast, and rice.

Fluids (water, juice, decaffeinated teas) are also vital to avoid dehydration. If you have symptoms of dehydration, go to the hospital immediately. Signs include extreme thirst, infrequent urination, dark-colored urine, fatigue, and dizziness.

In children, symptoms of dehydration include a dry tongue, no wet diapers for three hours, weakness, irritability, and crying without tears.