Foodborne illness
Foodborne illness (also foodborne disease and food poisoning)[1] is any illness resulting from the contamination of food by pathogenic bacteria, viruses, or parasites,[2] as well as prions (the agents of mad cow disease), and toxins such as aflatoxins in peanuts, poisonous mushrooms, and various species of beans that have not been boiled for at least 10 minutes.
For the disease most commonly referred to as food poisoning, see Salmonellosis.
Symptoms vary depending on the cause. They often include vomiting, fever, and aches, and may include diarrhea. Bouts of vomiting can be repeated with an extended delay in between. This is because even if infected food was eliminated from the stomach in the first bout, microbes, like bacteria (if applicable), can pass through the stomach into the intestine and begin to multiply. Some types of microbes stay in the intestine.
For contaminants requiring an incubation period, symptoms may not manifest for hours to days, depending on the cause and on the quantity of consumption. Longer incubation periods tend to cause those affected to not associate the symptoms with the item consumed, so they may misattribute the symptoms to gastroenteritis, for example.
Mechanism[edit]
Incubation period[edit]
The delay between the consumption of contaminated food and the 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 bovine spongiform encephalopathy), depending on the agent, and on how much was consumed. If symptoms occur within one to six 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 those affected to attribute their symptoms to gastroenteritis.[68]
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.[69]
Infectious dose[edit]
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. Pathogens vary in minimum infectious dose; for example, Shigella sonnei has a low estimated minimum dose of < 500 colony-forming units (CFU) while Staphylococcus aureus has a relatively high estimate.[70]
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,[71] 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.
Gut microbiota unaccustomed to endemic organisms[edit]
Foodborne illness often occurs as travelers' diarrhea in persons whose gut microbiota is unaccustomed to organisms endemic to the visited region. This effect of microbiologic naïveté is compounded by any food safety lapses in the food's preparation.
Society and culture[edit]
United Kingdom[edit]
In postwar Aberdeen (1964) a large-scale (>400 cases) outbreak of typhoid occurred, caused by contaminated corned beef which had been imported from Argentina.[89] The corned beef was placed in cans and because the cooling plant had failed, cold river water from the Plate estuary was used to cool the cans. One of the cans had a defect and the meat inside was contaminated. This meat was then sliced using a meat slicer in a shop in Aberdeen, and a lack of cleaning the machinery led to spreading the contamination to other meats cut in the slicer. These meats were then eaten by the people of Aberdeen who then became ill.
Serious outbreaks of foodborne illness since the 1970s prompted key changes in UK food safety law. These included the death of 19 patients in the Stanley Royd Hospital outbreak[90] and the bovine spongiform encephalopathy (BSE, mad cow disease) outbreak identified in the 1980s. The death of 21 people in the 1996 Wishaw outbreak of E. coli O157[91][92] was a precursor to the establishment of the Food Standards Agency which, according to Tony Blair in the 1998 white paper A Force for Change Cm 3830, "would be powerful, open and dedicated to the interests of consumers".[93]
In May 2015, for the second year running, England's Food Standards Agency devoted its annual Food Safety Week to "The Chicken Challenge". The focus was on the handling of raw chicken in the home and in catering facilities in a drive to reduce the high levels of food poisoning from the campylobacter bacterium. Anne Hardy argues that widespread public education of food hygiene can be useful, particularly through media (TV cookery programmes) and advertisement. She points to the examples set by Scandinavian societies.[94]