What is Food intoxication?

Answer 1

Foodborne illness (also foodborne disease and colloquially referred to as food poisoning) is any illness resulting from the consumption of contaminated food.

There are two types of food poisoning: food infection and food intoxication. Food infection refers to the presence of bacteria or other microbes which infect the body after consumption. Food intoxication refers to the ingestion of toxins contained within the food, including bacterially produced exotoxins, which can happen even when the microbe that produced the toxin is no longer present or able to cause infection. In spite of the common term food poisoning, most cases are caused by a variety of pathogenic bacteria, viruses, prions or parasites that contaminate food, rather than chemical or natural toxins.




Causes

Badly stored food in a fridgeFoodborne illness usually arises from improper handling, preparation, or food storage. Good hygiene practices before, during, and after food preparation can reduce the chances of contracting an illness. There is a general consensus in the public health community that regular hand-washing is one of the most effective defenses against the spread of foodborne illness. The action of monitoring food to ensure that it will not cause foodborne illness is known as food safety. Foodborne disease can also be caused by a large variety of toxins that affect the environment. For foodborne illness caused by chemicals, see Food contaminants.

Foodborne illness can also be caused by pesticides or medicines in food and naturally toxic substances like poisonous mushrooms or reef fish.


Symptoms and mortality
Symptoms typically begin several hours to several days after consumption and depending on the agent involved, can include one or more of the following: nausea, abdominal pain, vomiting, diarrhea, gastroenteritis, fever, headache or fatigue.

In most cases the body is able to permanently recover after a short period of acute discomfort and illness. However, foodborne illness can result in permanent health problems or even death, especially for people at high risk, including babies, young children, pregnant women (and their fetuses), elderly people, sick people and others with weak immune systems.

Foodborne illness due to campylobacter, yersinia, salmonella or shigella infection is a major cause of reactive arthritis, which typically occurs 1–3 weeks after diarrheal illness. Similarly, people with liver disease are especially susceptible to infections from Vibrio vulnificus, which can be found in oysters or crabs.

Tetrodotoxin poisoning from reef fish and other animals manifests rapidly as numbness and shortness of breath, and is often fatal.


Incubation period
The delay between consumption of a contaminated food and appearance of the first symptoms of illness is called the incubation period. This ranges from hours to days (and rarely months or even years, such as in the case of Listeriosis or Creutzfeldt-Jacob disease), depending on the agent, and on how much was consumed. If symptoms occur within 1–6 hours after eating the food, it suggests that it is caused by a bacterial toxin or a chemical rather than live bacteria.

The long incubation period of many foodborne illnesses tends to cause sufferers to attribute their symptoms to "stomach flu".

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.


Infectious dose
The infectious dose is the amount of agent that must be consumed to give rise to symptoms of foodborne illness, and varies according to the agent and the consumer's age and overall health. In the case of Salmonella a relatively large inoculum of 1 million to 1 billion organisms is necessary to produce symptoms in healthy human volunteers, as Salmonellae are very sensitive to acid. An unusually high stomach pH level (low acidity) greatly reduces the number of bacteria required to cause symptoms by a factor of between 10 and 100.


Pathogenic agents
See also: Pathogen

Bacteria
Bacteria are a common cause of foodborne illness. In the United Kingdom during 2000 the individual bacteria involved were as follows: Campylobacter jejuni 77.3%, Salmonella 20.9%, Escherichia coli O157:H7 1.4%, and all others less than 0.1%. In the past, bacterial infections were thought to be more prevalent because few places had the capability to test for norovirus and no active surveillance was being done for this particular organism. Symptoms for bacterial infections are delayed because the bacteria need time to multiply. They are usually not seen until 12–72 hours or more after eating contaminated food.

Most common bacterial foodborne pathogens are:

Campylobacter jejuni which can lead to secondary Guillain-Barré syndrome and periodontitis
Clostridium perfringens, the "cafeteria germ"
Salmonella spp. - its S. typhimurium infection is caused by consumption of eggs that are not adequately cooked or by other interactive human-animal pathogens
Escherichia coli O157:H7 enterohemorrhagic (EHEC) which causes hemolytic-uremic syndrome
Other common bacterial foodborne pathogens are:

Bacillus cereus
Escherichia coli, other virulence properties, such as enteroinvasive (EIEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), enteroaggregative (EAEC or EAgEC)

SalmonellaListeria monocytogenes
Shigella spp.
Staphylococcus aureus
Streptococcus
Vibrio cholerae, including O1 and non-O1
Vibrio parahaemolyticus
Vibrio vulnificus
Yersinia enterocolitica and Yersinia pseudotuberculosis
Less common bacterial agents:

Brucella spp.
Corynebacterium ulcerans
Coxiella burnetii or Q fever
Plesiomonas shigelloides

Exotoxins
In addition to disease caused by direct bacterial infection, some foodborne illnesses are caused by exotoxins which are excreted by the cell as the bacterium grows. Exotoxins can produce illness even when the microbes that produced them have been killed. Symptoms typically appear after 1–6 hours depending on the amount of toxin ingested.

Clostridium botulinum
Clostridium perfringens
Staphylococcus aureus
Bacillus cereus
For example Staphylococcus aureus produces a toxin that causes intense vomiting. The rare but potentially deadly disease botulism occurs when the anaerobic bacterium Clostridium botulinum grows in improperly canned low-acid foods and produces botulin, a powerful paralytic toxin.

Pseudoalteromonas tetraodonis, certain species of Pseudomonas and Vibrio, and some other bacteria, produce the lethal tetrodotoxin, which is present in the tissues of some living animal species rather than being a product of decomposition.


Mycotoxins and alimentary mycotoxicoses
The term alimentary mycotoxicoses refers to the effect of poisoning by Mycotoxins through food consumption. Mycotoxins have prominently affected on human and animal health such as an outbreak which occurred in the UK in 1960 that caused the death of 100,000 turkeys which had consumed aflatoxin-contaminated peanut meal and the death of 5000 human lives by Alimentary toxic aleukia (ALA) in the USSR in World War II. The common foodborne Mycotoxins include

Aflatoxins - originated from Aspergillus parasiticus and Aspergillus flavus. They are frequently found in tree nuts, peanuts, maize, sorghum and other oilseeds, including corn and cottonseeds. The pronounced forms of Aflatoxins are those of B1, B2, G1, and G2, amongst which Aflatoxin B1 predominantly targets the liver, which will result in necrosis, cirrhosis, and carcinoma . In the US, the acceptable level of total aflatoxins in foods is less than 20 µg/kg, except for Aflatoxin M1 in milk, which should be less than 0.5 µg/kg . The official document can be found at FDA's website .
Altertoxins - are those of Alternariol (AOH), Alternariol methyl ether (AME), Altenuene (ALT), Altertoxin-1 (ATX-1), Tenuazonic acid (TeA) and Radicinin (RAD), originated from Alternaria spp. Some of the toxins can be present in sorghum, ragi, wheat and tomatoes . Some research has shown that the toxins can be easily cross-contaminated between grain commodities, suggesting that manufacturing and storage of grain commodities is a critical practice.
Citrinin -
Citreoviridin -
Cyclopiazonic acid -
Cytochalasins
Ergot alkaloids / Ergopeptine alkaloids - Ergotamine
Fumonisins - Crop corn can be easily contaminated by the fungi Fusarium moniliforme, and its Fumonisin B1 will cause Leukoencephalomalacia (LEM) in horses, Pulmonary edema syndrome (PES) in pigs, liver cancer in rats and Esophageal cancer in humans . For human and animal health, both the FDA and the EC have regulated the content levels of toxins in food and animal feed .
Fusaric acid -
Fusarochromanone -
Kojic acid -
Lolitrem alkaloids -
Moniliformin -
3-Nitropropionic acid -
Nivalenol -
Ochratoxins - In Australia, The Limit of Reporting (LOR) level for Ochratoxin A (OTA) analyses in 20th Australian Total Diet Survey was 1 µg/kg [23], whereas the EC restricts the content of OTA to 5 µg/kg in cereal commodities, 3 µg/kg in processed products and 10 µg/kg in dried vine fruits .
Oosporeine -
Patulin - Currently, this toxin has been advisably regulated on fruit products. The EC and the FDA have limited it to under 50 µg/kg for fruit juice and fruit nectar, while limits of 25 µg/kg for solid-contained fruit products and 10 µg/kg for baby foods were specified by the EC
Phomopsins -
Sporidesmin A -
Sterigmatocystin -
Tremorgenic mycotoxins - Five of them have been reported to be associated with molds found in fermented meats. These are Fumitremorgen B, Paxilline, Penitrem A, Verrucosidin, and Verruculogen .
Trichothecenes - sourced from Cephalosporium, Fusarium, Myrothecium, Stachybotrys and Trichoderma. The toxins are usually found in molded maize, wheat, corn, peanuts and rice, or animal feed of hay and straw . Four trichothecenes, T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS) and deoxynivalenol (DON) have been most commonly encountered by humans and animals. The consequences of oral intake of, or dermal exposure to, the toxins will result in Alimentary toxic aleukia, neutropenia, aplastic anemia, thrombocytopenia and/or skin irritation . In 1993, the FDA issued a document for the content limits of DON in food and animal feed at an advisory level . In 2003, US published a patent that is very promising for farmers to produce a trichothecene-resistant crop .
Zearalenone -
Zearalenols -

Emerging foodborne pathogens
Many foodborne illnesses remain poorly understood. Approximately sixty percent of outbreaks are caused by unknown sources.[citation needed]

Aeromonas hydrophila, Aeromonas caviae, Aeromonas sobria

Preventing bacterial food poisoning
Prevention is mainly the role of the state, through the definition of strict rules of hygiene and a public services of veterinary surveying of animal products in the food chain, from farming to the transformation industry and delivery (shops and restaurants). This regulation includes:

traceability: in a final product, it must be possible to know the origin of the ingredients (originating farm, identification of the harvesting or of the animal) and where and when it was processed; the origin of the illness can thus be tracked and solved (and possibly penalized), and the final products can be removed from the sale if a problem is detected;
enforcement of hygiene procedures like HACCP and the "cold chain";
power of control and of law enforcement of veterinarians.
In August 2006, the United States Food and Drug Administration approved Phage therapy which involves spraying meat with viruses that infect bacteria, and thus preventing infection. This has raised concerns, because without mandatory labelling consumers wouldn't be aware that meat and poultry products have been treated with the spray.

At home, prevention mainly consists of good food safety practices. Many forms of bacterial poisoning can be prevented even if food is contaminated by cooking it sufficiently, and either eating it quickly or refrigerating it effectively[citation needed]. Many toxins, however, are not destroyed by heat treatment.


Viruses
Viral infections make up perhaps one third of cases of food poisoning in developed countries. In the US, more than 50% of cases are viral and noroviruses are the most common foodborne illness, causing 57% of outbreaks in 2004. Foodborne viral infection are usually of intermediate (1–3 days) incubation period, causing illnesses which are self-limited in otherwise healthy individuals, and are similar to the bacterial forms described above.


RotavirusEnterovirus
Hepatitis A is distinguished from other viral causes by its prolonged (2–6 week) incubation period and its ability to spread beyond the stomach and intestines, into the liver. It often induces jaundice, or yellowing of the skin, and rarely leads to chronic liver dysfunction. The virus has been found to cause the infection due to the consumption of fresh-cut produce which has fecal contamination .
Hepatitis E
Norovirus
Rotavirus

Parasites
Most foodborne parasites are zoonoses.

Platyhelminthes:

Diphyllobothrium sp.

The scolex of Tenia soliumNanophyetus sp.
Taenia saginata
Taenia solium
Fasciola hepatica
See also: Tapeworm and Flatworm

Nematode:

Anisakis sp.
Ascaris lumbricoides
Eustrongylides sp.
Trichinella spiralis
Trichuris trichiura
Protozoa:


Giardia lambliaAcanthamoeba and other free-living amoebae
Cryptosporidium parvum
Cyclospora cayetanensis
Entamoeba histolytica
Giardia lamblia
Sarcocystis hominis
Sarcocystis suihominis
Toxoplasma gondii

Natural toxins
Several foods can naturally contain toxins, many of which are not produced by bacteria. Plants in particular may be toxic; animals which are naturally poisonous to eat are rare. In evolutionary terms, animals can escape being eaten by fleeing; plants can use only passive defenses such as poisons and distasteful substances, for example capsaicin in chili peppers and pungent sulfur compounds in garlic and onions. Most animal poisons are not synthesised by the animal, but acquired by eating poisonous plants to which the animal is immune, or by bacterial action.

Alkaloids
Ciguatera poisoning
Grayanotoxin (honey intoxication)
Mushroom toxins
Phytohaemagglutinin (red kidney bean poisoning; destroyed by boiling)
Pyrrolizidine alkaloids
Shellfish toxin, including paralytic shellfish poisoning, diarrhetic shellfish poisoning, neurotoxic shellfish poisoning, amnesic shellfish poisoning and ciguatera fish poisoning
Scombrotoxin
Tetrodotoxin (fugu fish poisoning)
Some plants contain substances which are toxic in large doses, but have therapeutic properties in appropriate dosages.

Foxglove contains cardiac glycosides.
Poisonous hemlock (conium) has medicinal uses.

Other pathogenic agents
Prions, resulting in Creutzfeldt-Jakob disease

"Ptomaine poisoning"
An early theory on the causes of food poisoning involved ptomaines (from Greek ptoma, "fall, fallen body, corpse"), alkaloids found in decaying animal and vegetable matter. While some alkaloids do cause poisoning, the discovery of bacteria left the ptomaine theory obsolete and the word ptomaine is no longer used scientifically.