Doctors

Food poisoning is caused by consuming foods which are contaminated with any combination of four pathogenic substances, these being; bacteria, toxins, viruses, and/or parasites. Contamination typically arises from improper handling, preparation or storage of food. Food poisoning can also be caused by adding pesticides or medicines to food, or by accidentally consuming naturally poisonous substances such as poisonous mushrooms or non-edible substances. Contact between food and pests, especially flies, rodents and cockroaches, is another potential cause of the contamination of food.

The World Health Organization defines food poising as:

"diseases, usually either infectious or toxic in nature, caused by agents that enter the body through the ingestion of food. Every person is at risk of food borne illness."

food poisoning symptoms

Symptoms of food poisoning typically begin several hours after ingestion and depending on the agent involved, can include one or more of the following symptoms:

• nausea and upset stomach
• abdominal pain
• vomiting
• diarrhea
• fever
• headache
• lack of energy

In most cases the body is able to find balance after a short period of discomfort and illness. That said, food borne illness can result in permanent health problems and even death. The most at risk for further complications are babies, pregnant women, the elderly, those with chronic illness, and others with compromised immune systems.

early symptoms of food poisoning

The delay between consumption of a contaminated food and the appearance of the first symptoms of illness is called the incubation period. This ranges from hours to days, depending on the agent, and on how much was consumed.

During the incubation period, microbes pass through the stomach into the intestine, attach to the cells lining the intestinal walls, and begin to multiply there. Some types of microbes stay in the intestine, some produce a toxin that is absorbed into the bloodstream, and some can directly invade the deeper body tissues. The symptoms produced depend on the type of microbe.

a deeper look at the causes

Bacterial infection is the most common cause of food poisoning. Symptoms for bacterial infections are delayed because the bacteria need time to multiply. They are usually not seen until 12-36 hours after eating contaminated food.

• Campylobacter: A cause of mild food born illness. The infection features 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 waste.
• Salmonellae: A cause of moderate food poisoning featuring nausea, vomiting, diarrhea, cramping, and headaches. Often, the infection reemerges a few weeks later as arthritis (joint pains). In people with impaired immune systems, salmonellae can become a life-threatening illness. Salmonellae is transmitted by under cooked foods such as eggs, poultry, dairy products, and seafood.
• Shigella (travelers diarrhea): A cause of moderate to severe food born illness. Symptoms may include fever; diarrhea containing blood or mucus or both, and the constant urge to have bowel movements. Shigella is transmitted in water polluted with human wastes.
• Clostridium botulinum (botulism): A cause of severe food poisoning. Botulism affects the nervous system. Symptoms of botulism start as blurred vision. The person then has problems talking and displays overall weakness. Symptoms then progress to breathing difficulty and inability to move arms or legs. Botulism is transmitted in foods such as home-packed canned goods, honey, sausages, and seafood.
• Escherichia coli (E coli): A causes of moderate to severe food born illness. The infection begins with a large amount of watery diarrhea, and then turns into bloody diarrhea. E coli is transmitted by eating raw or under cooked hamburger, unpasteurized milk or juices, or contaminated well water.
• Staphylococcus aureus: A cause of moderate to severe illness with rapid onset of nausea, severe vomiting, dizziness, and abdominal cramping. Staphylococcus aureus produces a toxin on foods such as cream-filled cakes and pies, creamy salads, and dairy products. Contaminated potato salad is a common example.
• Bacillus cereus: A cause of mild illness which displays rapid onset of vomiting. Bacillus Cereus is most often found in rice, often fried rice, and other starchy foods such as pasta and/or potatoes.
• Vibrio cholerae: A cause of mild to moderate illness. Vibrio cholerae symptoms include crimpy diarrhea, headache, nausea, vomiting, and fever with chills. It strikes mostly in the warmer months of the year and is transmitted by infected, under cooked, or raw seafood.

Viral infections make up perhaps one third of cases of food poisoning in developed countries. They are usually of intermediate (1-3 days) incubation period, cause illnesses which is self-limited in otherwise healthy individuals.

• Norwalk virus: A causes of mild illness with nausea, vomiting, diarrhea, abdominal pain, headache, and low-grade fever. The symptoms of norwalk virus usually resolve in 2-3 days. It is the most common viral cause of adult food poisoning. The Norwalk virus is transmitted from water, shellfish, and vegetables contaminated by feces, as well as from person to person.
• Rotavirus: 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.
• Hepatitis A: Hepatitis A ( also known as Hep A ) is a disease affecting the liver, and caused by the Hepatitis A virus (abbreviated HAV). Only 3 out of 4 people with hepatitis A have symptoms.
  Hepatitis A symptoms may include; jaundice (showing up first as yellow eyes), dark urine, nausea, fever, tiredness, loss of appetite, stomach ache, and vomiting.

Several foods can naturally contain toxins which are not produced by bacteria and occur naturally in foods. The incubation period for this type of illness is 1-2 hours.