Foodborne Disease Caused by Micro-organisms

Foodborne Disease Caused by Micro-organisms
Foodborne disease is a public health problem which comprises a broad group of illnesses.

Among them, gastroenteritis is the most frequent clinical syndrome which can be attributed to a wide range of micro-organisms, including bacteria viruses and parasites.

Usually, the incubation period is short, from 1-2 days to 7 days.

Different degrees in severity are observed, for a mild disease which does not require medical treatment at the more serious illness requiring hospitalization, long term disability and /or death.

The outcome of exposure to foodborne diarrheal pathogens depends on a number of host factors including preexisting immunity, the ability to elicit an immune response, nutrition, age, and non specific host factors.

As a result, the incidence the severity and the lethality of foodborne diarrhea is much higher in some particularly vulnerable segments of the population, including children under five years of age, pregnant women, immuno-compromised people and elderly.

In addition to these well known predisposing conditions, new ones are regularly identified (liver disease for paraheamoliticus septicemia, thalassemia for Yersinia enterocolitica infections).

Serious complications may result from these illnesses including intestinal as well as systemic manifestations, like hemolytic uremic syndrome for 10% of Escherichia coli 0157:H7 infections with bloody diarrhea, Guillain-Barre syndrome (nerve degeneration, slow recovery and severe residual disability) after Campylobacter jejuni infection, reactive arthritis after salmonellosis and chronic toxoplasmic encephalitis.

While diarrhea is the most common syndrome following the consumption of a contaminated food some disease are more serious.

Clinical manifestations of listeriosis include bacteriemia and central nervous system infections, especially in patients with an impairment of T-cell mediated immunity and abortion in pregnant women, with an overall case fatality rate of 25%.

Food borne botulism is a result from the potent toxin by Clostridium botulinum that cause a paralysis of skeletal and respiratory muscles which, when severe may result in death in 8% of cases.

Toxoplasma gondii is also the most frequent cause of lesion in the central nervous system in patients with AIDS.

Hepatitis A is an infectious disease for which age is the most important determinant of morbidity and mortality, with severity of illness and its complications increasing with age.

The durations of illness vary but most cases are symptomatic for three weeks.

Complications during the acute illness phase are unusual, with fulminant hepatitis and death being uncommon.
Foodborne Disease Caused by Micro-organisms

Bacillus cereus: Toxin and Spore Producing Bacteria

Bacillus cereus: Toxin and Spore Producing Bacteria
Bacillus cereus, a spore forming microorganisms, is present in soil and can be isolated from a wide variety of vegetation and food. It has been found to be present in the intestinal tract of 10 percent of healthy adults. It is often present in dairy products, meats, spices, dried products, and cereals (particularly rice). Food products implicated in this type of illness have included: cereal dishes containing corn and cornstarch, potatoes, vegetables, meat product, puddings, soups, sauces, fried rice, and ilk and dairy products. Vegetative cells of Bacillus cereus are destroyed by most cooking processes, but heat resistant spores survive.

When cooked food containing spores of Bacillus cereus is cooled and allowed to remain at warm kitchen temperatures, the spores germinate to form viable cells. The population of cells increases in the food. Illness results form ingestion of food containing a large number of cells of Bacillus cereus, that then produce toxin in intestine.
There are two types of Bacillus cereus foodborne illness:

Diarrheal illness
The Diarrheal illness is most often associated with meat product, soups, potatoes and starchy vegetables, puddings, and sauces. The onset of symptoms occurs 8 to 16 hours after ingestion of food containing the microorganisms or toxin. Symptoms include abdominal pain and diarrhea and occasionally, nausea and vomiting.

Emetic illness
The emetic form of illness may result in diarrhea and abdominal cramps, but is most often characterized by nausea and vomiting. Its onset occurs 1 to 5 hours after ingestion. The duration of illness is from 6 to 24 hours. These types of illness is most often associated with the rice dishes and pasta products that were held at improper temperatures and slow cooling of large quantities of foods.

Critical problems in today’s food supply that lead to illness caused by Bacillus cereus are:

• Holding cooked foods at room temperatures for along periods of time prior to reheating or serving them.

• Cooling foods at temperatures that allow the germination and growth of cells of Bacillus cereus.

• Failure of foodservice personnel to use good personal hygiene when working on foodservice facilities. People can be carriers of this microorganism. If they do not wash their hands and under their fingernails after defecating, they can transmit this pathogen to anything they touch or handle.

Bacillus cereus: Toxin and Spore Producing Bacteria

Food Habits May Cause Problems

Food Habits May Cause Problems
New convenience foods, such as precooked entrees prepared for quick reheating at home or in restaurants, pose new food safety risks than can further increase the foodborne illness problem. For instance, vacuum packaging hinders the growth of spoilage microorganisms but may permit the production of botulism toxin at temperatures common in many commercial and home refrigerators.

Some precooked foods may receive only minimal reheating. This technique eliminates the traditional last line of defense. The consumer of today has the misconception that minimally cooked food is more healthful. Nouvelle cuisine in restaurants emphasizes minimally cooked food. The widespread use of microwave ovens also contributes to the foodborne illness problem because food cooked or reheated in these units is not heated uniformly, which allows bacteria and parasites to survive. Because of the lack of food safety education of food industry personnel, coupled with contamination of the food, the food can become hazardous.

There are also problem with fresh seafood, which is currently exempt from mandatory federal inspection. As suppliers search for inexpensive source of food, more foods are imported. This increased the risk because foreign processors can have less control than American food processors.
Food Habits May Cause Problems