Human Digestive system - Food-Poisoning

Digestive system-food poisoning

Food Poisoning Overview

Food poisoning is a common, usually mild, but sometimes deadly illness. Typical symptoms include nausea, vomiting, abdominal cramping, and diarrhea that occur suddenly (within 48 hours) after consuming a contaminated food or drink. Depending on the contaminant, fever and chills, bloody stools, dehydration, and nervous system damage may follow. These symptoms may affect one person or a group of people who ate the same thing (called an outbreak).

Food Poisoning Causes

The known causes of food poisoning can be divided into two : infectious agents and toxic agents. Infectious agents include viruses, bacteria, and parasites. Toxic agents include poisonous mushrooms, improperly prepared exotic foods (such as barracuda), or pesticides on fruits and vegetables. Food usually becomes contaminated from poor sanitation or preparation. Food handlers who do not wash their hands after using the bathroom or have infections themselves often cause contamination. Improperly packaged food stored at the wrong temperature also promotes contamination.

Food Poisoning Symptoms

Symptoms of food poisoning depend on the type of contaminant and the amount eaten. The symptoms can develop rapidly, within 30 minutes, or slowly, worsening over days to weeks. Most of the common contaminants cause nausea, vomiting, diarrhea, and abdominal cramping. Usually food poisoning is not serious, and the illness runs its course in 24-48 hours. Viruses account for most food poisoning cases where a specific contaminant is found.


are a group of viruses that cause a mild illness (often termed stomach flu) with nausea, vomiting, diarrhea, abdominal pain, headache, and low-grade fever. These symptoms usually resolve in two to three days. It is the most common viral cause of adult food poisoning and is transmitted from water, shellfish, and vegetables contaminated by feces, as well as from person to person. Outbreaks are more common in densely populated areas such as nursing homes, schools and cruise ships (hence why the virus is also known as the Cruise Ship Illness). The term norovirus has been approved as the official name for this group of viruses. Several other names have been used for noroviruses, including Norwalk-like viruses, caliciviruses (because they belong to the virus family Caliciviridae), and small round structured viruses.


Causes moderate to severe illness with vomiting followed by watery diarrhea and fever. It is the most common cause of food poisoning in infants and children and is transmitted from person to person by fecal contamination of food and shared play areas.

Hepatitis A:

Causes mild illness with sudden onset of fever, loss of appetite, and feeling of tiredness followed by jaundice, which is a yellowing of the eyes and skin. It is transmitted from person to person by fecal contamination of food.


can cause food poisoning in two different ways. Some bacteria infect the intestines, causing inflammation and difficulty absorbing nutrients and water, leading to diarrhea. Other bacteria produce chemicals in foods (known as toxins) that are poisonous to the human digestive system. When eaten, these chemicals can lead to nausea and vomiting, kidney failure, and even death.


Salmonellae are bacteria that may cause food poisoning; the illness itself is often referred to as Salmonella or Salmonella infection. Salmonellae cause a moderate illness with nausea, vomiting, crampy diarrhea, and headache, which may come back a few weeks later as arthritis (joint pains). In people with impaired immune systems (such as people with kidney disease or HIV/AIDS or those receiving chemotherapy for cancer), Salmonellae can cause a life-threatening illness. The illness is transmitted by undercooked foods such as eggs, poultry, dairy products, and seafood.


Causes mild illness with fever, watery diarrhea, headache, and muscle aches. Campylobacter is the most commonly identified food-borne bacterial infection encountered in the world. It is transmitted by raw poultry, raw milk, and water contaminated by animal feces.

Staphylococcus aureus:

Causes moderate to severe illness with rapid onset of nausea, severe vomiting, dizziness, and abdominal cramping. These bacteria produce a toxin in foods such as cream-filled cakes and pies, salads (most at risk are potato, macaroni, egg, and tuna salads, for example) and dairy products. Contaminated salads at picnics are common if the food is not chilled properly.

Bacillus cereus:

Causes mild illness with rapid onset of vomiting, with or without diarrhea and abdominal cramping. It is associated with rice (mainly fried rice) and other starchy foods such as pasta or potatoes. It has been speculated that this bacteria may also be used as a potential terrorist weapon.

Escherichia coli (E coli):

Causes moderate to severe illness that begins as large amounts of watery diarrhea, which then turns into bloody diarrhea. There are many different types of this bacteria. The worst strain can cause kidney failure and death (about 3%-5% of all cases). It is transmitted by eating raw or undercooked hamburger, unpasteurized milk or juices, or contaminated well water. Outbreaks of food poisoning due to E. coli have also occurred following ingestion of contaminated produce.

Shigella (travelers diarrhea):

Causes moderate to severe illness with fever, diarrhea containing blood or mucus or both, and the constant urge to have bowel movements. It is transmitted in water polluted with human wastes.

Clostridium botulinum (botulism):

Causes severe illness affecting the nervous system. Symptoms start as blurred vision. The person then develops problems talking and overall weakness. Symptoms then progress to breathing difficulty and the inability to move arms or legs. Infants and young children are particularly at risk. It is transmitted in foods such as home-packed canned goods, honey, sausages, and seafood.

Vibrio cholerae:

Causes mild to moderate illness with crampy diarrhea, headache, nausea, vomiting, and fever with chills. It strikes mostly in the warmer months of the year and is transmitted by infected, undercooked, or raw seafood.


rarely cause food poisoning. When they do, they are usually swallowed in contaminated or untreated water and cause long-lasting but mild symptoms.

Giardia (beaver fever):

Causes mild illness with watery diarrhea often lasting one to two weeks. It is transmitted by drinking contaminated water, often from lakes or streams in cooler mountainous climates. The infection can also be spread from person to person by food or other items contaminated with feces from an infected person.


Causes moderate illness with large amounts of watery diarrhea lasting two to four days. May become a long-lasting problem in people with poor immune systems (such as people with kidney disease or HIV/AIDS or those on chemotherapy for cancer). It is transmitted by contaminated drinking water.

Toxic agents

are the least common cause of food poisoning. Illness is often an isolated episode caused by poor food preparation or selection (such as picking wild mushrooms).

Mushroom toxins:

Illness can range from mild to deadly depending on the type of mushroom eaten. Often there is nausea, vomiting, and diarrhea. Some types of mushrooms produce a nerve toxin, which causes sweating, shaking, hallucinations, and coma.

Ciguatera poisoning: 

Caused by eating fish that contains toxins produced by a marine algae called Gambierdiscus toxicus. It can cause moderate to severe illness with numbness of the area around the mouth and lips that can spread to the arms and legs, nausea, vomiting, muscle pain and weakness, headache, dizziness, and rapid heartbeat. The toxin may cause sensory problems in which hot things feel cold and cold things feel hot. It is transmitted by eating certain large game fish from tropical waters-most specifically barracuda, grouper, snapper, and jacks. According to the CDC, ciguatera has no cure. Symptoms may disappear in days or weeks, but may persist for years.


Causes mild to moderate illness with facial flushing, burning around the mouth and lips, peppery-taste sensations, a red rash on the upper body, dizziness, headache, and itchy skin. Severe symptoms may include blurry vision, respiratory distress, and swelling of the tongue and mouth. Symptoms typically last from four to six hours, and rarely more than one or two days. It is transmitted in seafood, mostly mahi-mahi and tuna, but can also be in Swiss cheese.


Cause mild to severe illness with weakness, blurred vision, headache, cramps, diarrhea, increased production of saliva, and shaking of the arms and legs. Toxins are transmitted by eating unwashed fruits or vegetables contaminated with pesticides.

When to Seek Medical Care

Contact your doctor if any of the following situations occur: Nausea, vomiting, or diarrhea lasts for more than two days. The ill person is younger than three years. The abdominal symptoms are associated with a low-grade fever. Symptoms begin after recent foreign travel. Other family members or friends who ate the same thing are also sick. The ill person cannot keep any liquids down. The ill person does not improve within two days even though they are drinking large amounts of fluids. The ill person has a disease or illness that weakens their immune system (for example, HIV/AIDS, cancer and undergoing chemotherapy, kidney disease). The ill person cannot take their normal prescribed medications because of vomiting. The ill person has any nervous system symptoms such as slurred speech, muscle weakness, double vision, or difficulty swallowing. Go to the nearest hospital!!!s emergency department if any of the following situations occur: The ill person passes out or collapse, become dizzy, lightheaded, or have problems with vision. A fever higher than 101F occurs with the abdominal symptoms. Sharp or cramping pains do not go away after 10-15 minutes. The ill person!!!s stomach or abdomen swells. The skin and/or eyes turn yellow. The ill person is vomiting blood or having bloody bowel movements. The ill person stops urinating, have decreased urination, or have urine that is dark in color. The ill person develops problems with breathing, speaking, or swallowing. One or more joints swell or a rash breaks out on your skin. The ill person or caretaker considers the situation to be an emergency. , a thorough examination will be performed, including measurements of blood pressure, pulse, breathing rate, and temperature. The doctor will perform a physical exam, which screens for outward signs and symptoms of the illness. They will assess how dehydrated the patient is and examine the abdominal area to make sure the illness is not serious. The doctor may need to do a rectal examination. The doctor performs this test by inserting a lubricated and gloved finger gently into the rectum. The purpose is to make sure there are no breaks in the rectal wall. A sample of stool is taken and tested for blood and mucus. In some cases, a sample of stool or vomit can be sent to the laboratory for further testing to find out which toxin caused the illness. In a majority of cases, a specific cause is not found. A urine sample helps assess how dehydrated the patient is and may indicate possible kidney damage. Blood tests may be performed to determine the seriousness of the illness. An x-ray of the abdomen or a CT scan may be taken if the doctor suspects your symptoms may be caused by another illness.

Food Poisoning Treatment 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. Small, frequent sips of clear liquids (those you can see through) are the best way to stay hydrated. 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. 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.

Medical Treatment

The main treatment for food poisoning is putting fluids back in the body (rehydration) through an IV and by drinking. The patient may need to be admitted to the hospital. This depends on the severity of the dehydration, response to therapy, and ability to drink fluids without vomiting. Children, in particular, may need close observation. Anti-vomiting and diarrhea medications may be given. The doctor may also treat any fever to make the patient more comfortable. Antibiotics are rarely needed for food poisoning. In some cases, antibiotics worsen the condition. Only a few specific causes of food poisoning are improved by using these medications. The length of illness with traveler!!!s diarrhea (shigellae) can be decreased with antibiotics, but this specific illness usually runs its course and improves without treatment.


Safe steps in food handling, cooking, and storage are essential to avoiding food-borne illness. Bacteria cannot be seen, smelled, or tasted, which may be on any food. Follow the CDC food safety guidelines to keep contaminants away. Safe shopping Buy cold foods last during your shopping trip. Get them home fast. Never choose torn or leaking packages. Do not buy foods past their sell-by or expiration dates. Keep raw meat and poultry separate from other foods. Safe storage of foods Keep it safe; refrigerate. Unload perishable foods first and immediately refrigerate them. Place raw meat, poultry, or fish in the coldest section of your refrigerator. Check the temperature of your appliances. To slow bacterial growth, the refrigerator should be at 40F, the freezer at 0F. Cook or freeze fresh poultry, fish, ground meats, and variety meats within two days. Safe food preparation Keep everything clean! Wash hands before and after handling raw meat and poultry. Sanitize cutting boards often in a solution of one teaspoon chlorine bleach in one quart of water. Do not cross-contaminate. Keep raw meat, poultry, fish, and their juices away from other food. After cutting raw meats, wash hands, cutting board, knife, and counter tops with hot, soapy water. Marinate meat and poultry in a covered dish in the refrigerator. Discard any uncooked/unused marinade. Thawing food safely Refrigerator: Allows slow, safe thawing. Make sure thawing juices do not drip on other foods. Cold water: For faster thawing, place food in a leak-proof plastic bag and submerge in cold tap water. Microwave: Cook meat and poultry immediately after microwave thawing. Cook ground meats to 160F; ground poultry to 165F. Beef, veal, and lamb steaks, roasts and chops may be cooked to 145F; all cuts of fresh pork, 160F. Whole poultry should reach 180F in the thigh; breasts 170F. Never leave food out more than two hours (or more than one hour in temperatures above 90F). Bacteria that cause food poisoning grow rapidly at room temperature. Use cooked leftovers within four days.