NEWS | Sunday, 28 September 2008

How safe is safe food?

It is said that 40% of food borne illnesses cases registered in Malta originate in households. DAVID DARMANIN speaks to bacteriologist Joseph Tanti to understand what the common domestic hazards are

In recent years, the Public Health Regulation Division within the Department for Environmental Health carried out a sampling programme to find that an estimated 2% of the local lettuce may have been contaminated with Salmonella.
Species of Salmonella, a bacterium type that is often the cause of food-borne illnesses, are at times prevalent in the intestines of broiler flocks such as poultry. In some European countries, 68.2 per cent of broiler flocks sampled were found to be contaminated with this disease. Salmonella, however, will develop in the intestines of its carrier and any prevalence of it is usually found in the outer layers of the edible product, or in those parts which would have been in direct contact with contaminated intestines, faeces or carriers.
It is known that temperatures over 63 degrees Celsius kill this bacterium, so proper cooking should do the trick.
But lettuce, which could in the same way make direct contact with contaminated manure or water, is eaten raw. Washing or sanitisation will not always treat the product, as lettuce could easily absorb the bacterium and contain it within its leaves. Does this pose a risk to most of the Maltese population enjoying a salad every now and then?
Not according to Joseph Tanti, an independent bacteriologist who, when contacted by MaltaToday, said that the chances of contracting the disease from lettuce are very slim.
“Even if one is unlucky enough to contract Salmonella from lettuce,” he said, “how can you control a mouse, carrying the bacterium, from defecating on soil in a lettuce field? Even if one takes full precautions, these things are bound to happen, but you have to be extremely unlucky. Food safety is not about that. Food safety is about doing all that is possible to minimise the risk of food contamination. You cannot eradicate the risk completely, and even minimising it often presents a huge challenge.”
Quoting an estimation made by the Health Department, Tanti said that about 40% of food-borne illnesses recorded at hospital originate from food prepared in households.
“We should much rather worry about practices that are generally considered acceptable at home, but that in fact carry enormous risks of contamination,” he added.
A survey carried out by science student Sacha Buttigieg, under the supervision of Tanti, quotes that out of 400 people responsible for the shopping and preparation of food in households, 33.1% were not interested in attending a course to learn more about food safety.
Out of 14 basic questions asked on food safety, 5.2% of respondents knew none of the answers or gave the wrong answers, 29.9% knew four or less, and 21.3% knew five or six. Only one respondent knew all 14.
Asked to provide five examples of common hazardous household practice, Tanti gave off-hand examples so quickly that it seemed the list was endless.

Buying bread
“How many times have you entered a bakery to see customers touching loaves to test their freshness?” Tanti asked. “What guarantees that bread would not have been touched by a customer who would have been in contact with raw meats previously, say at the butcher’s? This practice carries the risk of an E.coli 0157 infection, among others.”
Although most Escherichia Coli (E.coli) strains are harmless, the serotype Tanti refers to, as well as other virulent strains, can cause gastroenteritis, urinary tract infections, and neonatal meningitis. In rarer cases, virulent strains are also responsible for hæmolytic-uremic syndrome (HUS), peritonitis, mastitis, septicaemia and Gram-negative pneumonia. Recently it is thought that E.coli and certain other food borne illnesses can sometimes trigger serious health problems months or years after patients survived that initial bout.

Mind your fridge
“Storing all meats, apart from fish, on top shelves in fridges carries a very high risk. Leakage of liquids onto a salad for example, could cause Salmonella,” he said.
Most persons infected with Salmonella develop diarrhoea, fever, vomiting, and abdominal cramps 12 to 72 hours after infection. In most cases, the illness lasts 3 to 7 days and most affected persons recover without treatment. However, in some persons the diarrhoea may be so severe that the patient becomes dangerously dehydrated and must be taken to a hospital. At the hospital, the patients may receive intravenous fluids to treat their dehydration and medications may be given to provide symptomatic relief, like fever reduction. In severe cases, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites and can cause death unless the person is treated promptly with antibiotics. The elderly, infants, and those with impaired immune systems are more likely to have a severe illness. Some people afflicted with Salmonellosis later experience reactive arthritis, which can have long-lasting, disabling effects.

Pre-washing veg
“Not pre-washing your vegetables before putting them in the fridge is absolute madness,” Tanti stressed. Soil carries Claustridia, which is extremely dangerous when in contact with high-risk food. Clostridium botulinum is an anaerobic, Gram-positive, spore-forming rod that produces a potent neurotoxin. The spores are heat-resistant and can survive in foods that are incorrectly or minimally processed. Onset of symptoms in foodborne botulism, caused by Clostridia, is usually 18 to 36 hours after ingestion of the food containing the toxin, although cases have varied from four hours to eight days. Early signs of intoxication consist of marked lassitude, weakness and vertigo, usually followed by double vision and progressive difficulty in speaking and swallowing. Difficulty in breathing, weakness of other muscles, abdominal distention, and constipation may also be common symptoms.
Clinical symptoms of infant botulism consist of constipation that occurs after a period of normal development. This is followed by poor feeding, lethargy, weakness, pooled oral secretions, and wail or altered cry. Loss of head control is striking. Recommended treatment is primarily supportive care. Antimicrobial therapy is not recommended. Infant botulism is diagnosed by demonstrating botulinal toxins and the organism in the infants' stools.

Carry your picnic cooler when out shopping
“Imagine you go to the butcher shop, buy some meat, and proceed to go to the baker’s and then to the stationer’s. In the car, at those temperatures, Salmonella reproduces very fast.”
Bacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction. Under optimal conditions, bacteria can grow and divide extremely rapidly, and bacterial populations can double as quickly as every 9.8 minutes. In cell division, two identical clone daughter cells are produced. Some bacteria, while still reproducing asexually, form more complex reproductive structures that help disperse the newly-formed daughter cells.

Careful before eating sushi
“Beyond 4 degrees Celsius, tuna, mackerel and lampuki produce histamines,” he said. “If you get a serious enough allergy, such as scombroid poisoning, it could be fatal. We must ensure to never, ever purchase tuna from fish shops keeping it out on the workbench at room temperature.”
Scombroid poisoning (or histamine poisoning) is caused by the ingestion of foods that contain high levels of histamine. Early symptoms may include a tingling or burning sensation in the mouth, a rash on the upper body and a drop in blood pressure. Headaches and itchy skin are common. The symptoms may progress to nausea, vomiting, and diarrhoea. Sufferers may require hospitalisation, particularly the elderly or those with existing health conditions.
Symptoms occur very rapidly, from immediately to 30 minutes after eating contaminated fish. They usually subside between three and 24 hours after consumption, but may last several days.
While rarely fatal, the condition can be very distressing, with individuals often requiring medical consultations and occasionally hospitalisation.


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