Food scares

TheSite's list of favourite food scares. Be afraid, be very afraid.

Salmonella

Incubation period: 12 to 72 hours.

Symptoms: Diarrhoea, vomiting and fever. Fatal in around 3% of those infected with salmonella DT 104, the most dangerous strain of the infection.

Source of infection: Although contaminated meat is the main source of infection, it was the discovery of salmonella in British eggs that led to Edwina Currie's resignation. Predominantly from foodstuffs (most commonly red and white meats, raw eggs, milk, and dairy products) following contamination of cooked food by raw food or failing to achieve adequate cooking temperatures. Person to person spread from a case by close contact, usually during the acute diarrhoeal phase of the illness. Contact with infected animals.

Occurrence: There are around 4,000 recorded cases of DT 104 each year.

Major scares: 1988 was the time of Edwina's eggs. In 2000 the Government reported that 23% of pigs taken for slaughter are infected with salmonella.

BSE

Incubation period: Incubation periods may vary depending on the specific gene combination of each individual.

Symptoms: The disease, which usually only affects the elderly, causes epilepsy, blindness and brain degeneration; there is no treatment and the outcome is always fatal.

Source of infection: BSE (bovine spongiform encephalopathy) developed from a similar disease called scrapie, which affects sheep. Cows carry BSE, however it is the practice of meat by-products being used in cattle feed that is believed to be responsible for the transmission of CJD (Creuzfeldt-Jakob disease) to humans.

Occurrence: So far, just over 100 people in Britain are thought to have died from the variant form of the disease, Variant CJD (vCJD).

Major scares: During the early 1990s, the Government issued a series of guidelines and orders to try to halt the spread of BSE. The Chief Medical Officer assured the public in 1990 and 1993 that beef was safe to eat. Infections in cows reached their peak in 1993, and in July the 100,000th case was announced. In 1995, doctors reported the first suspected incident of BSE-related CJD in a human. More cases followed. The Government resolved in 1996 that no cattle over the age of 30 months should enter the food chain and beef exports were banned. Last year the EU agreed to permit the export of British beef to Europe.

E-coli

Incubation period: Between one day and two weeks.

Symptoms: Sometimes it causes diarrhoea, and in other cases (particularly among children and the elderly) it can be fatal.

Source of infection: The majority of cases are due to undercooked meat, when intestinal content has contaminated the carcass at slaughter, or from raw milk. Although E coli bacteria are present in the human intestinal tract, it is the different strains that lead to illness.

Major scares: Concern over E coli reached a peak in 1997, when there were three serious outbreaks in Scotland. One of these outbreaks, linked to a single butcher's in Lanarkshire killed 22.

Listeria

Incubation period: This can be as long as 10 weeks, and this causes considerable difficulty in determining the food implicated in the infection.

Symptoms: Listeria causes very serious types of illness including meningitis and septicaemia and the mortality rate can be as high as 30%. The most vulnerable people are pregnant women; their infants; the elderly and people who are immunosuppressed.

Source of infection: Environment, cattle, sheep, soil, silage. The majority of cases are believed to be foodborne - the bacterium has been isolated from a range of raw foods including vegetables and uncooked meats as well as processed foods, soft cheeses and meat-based patis. There have been some cases where infection was by direct contact with animals. Pregnant women are the other big risk; infection has been passed from Mother to foetus in utero, during birth and via person to person spread between infants shortly after delivery.

Major scares: Outbreak in 1989 turned consumers off supermarket soft cheese and cooked chicken.