Food Borne Disease

Toxoplasma gondii

2012-01-17T18:05:00.000-08:00

Toxoplasma gondii is a protozoan parasite which can be transmitted by fecal-oral contamination. Cats are the original hosts for this protozoa. They excrete microscopic in active forms of this protozoa in their feces. Farm animals (notably sheep and pigs) become infected by consuming feed and water contaminated by barn cats’ fecal material.

Active forms of this parasite then multiply with the farm animals and encyst themselves in the brain, heart muscle, other skeletal muscle, and liver. The cysts are microscopic and can exists as long as the farm animal lives.

When these animals are slaughtered to provide meat, the raw meat contains the cysts which can then infected humans if it is eaten raw or not heated sufficiently to inactive various forms of this parasite. About 30% of all fresh pork is infected and is the main meat source of Toxoplasma gondii in the United Sates.

If cutting and grinding equipment is not thoroughly washed and sanitized, other raw meats such as ground beef can also become contaminated. About 5% of the ground beef sold in supermarket contains some pork because the grinding equipment is not properly cleaned between grinding operations. Cysts of this protozoa are also found in wild game meats such as elk, moose, and venison.

Symptoms of the disease in humans are fever, muscle aches, headaches, loss of appetite and sore throat. Other symptoms will appear, depending upon the internal organs involved. In pregnant women, these parasites can be carried by way of the placenta to fetal tissue. If fetuses are infected, spontaneous abortions may occur. Most infected infants show no obvious symptoms at birth, but will show signs of eye damage and mental retardation later in life.

It is estimated that there are over 3,300 cases of congenital Toxoplasmosis each year resulting in 450 deaths of infants and young children. Other surviving infected children are mentally retarded as a result of this parasitic infection.
Toxoplasma gondii

Waterborne disease microorganisms

2011-11-11T04:39:00.001-08:00

Waterborne disease causing organisms are for the most part in three general categories of microorganism. i.e. bacteria, protozoa and viruses. They made the water unsafe for human consumption.

In most cases, they originate for human and/or animal fecal wastes.

Waterborne viral agents and the diseases they cause include poliomyelitis virus (polio) and hepatitis A virus (hepatitis).

Waterborne bacteria and the diseases they cause include Escherichia coli (gastroenteritis), Legionella spp. (legionellosis), Salmonella typhi (typhoid fever), Shigella spp. (shigellosis or bacillary dysentery) and Vibrio cholerae (cholera).

A waterborne disease outbreak is a water exposure in which at least two persons have been epidemiologically linked to recreational or drinking water by location, time, and illness.

During late nineteenth and early twentieth century there were two waterborne diseases that posed the greatest threat to the American population: typhoid fever and diarrhea.

Typhoid fever is caused by Salmonella typhi, a bacterium that can survive only in human hosts and lives in the intestinal tract. People typically contracted the disease by drinking contaminated water.

More broadly, water caused diseases also include water-washed diseases caused by poor personal hygiene and skin or eye contact with contaminated water, water based diseases caused by parasites found in intermediate organisms living in water and water related diseases caused by insect vectors which breed in water.
Waterborne disease microorganisms

Effect on economy productivities by foodborne disease

2011-09-23T00:07:00.000-07:00

Foodborne disease has been identified by World Health Organization as – any disease of an infectious or toxic nature caused by, or thought to be caused by, the consumption of food or water.

Foodborne disease continues to be one of the largest public health problems worldwide, and is also an important cause of reduced economic productivities.

For example, economic loss from trichinosis, toxoplasmosis, salmonellosis, campylobacteriosis and beef tapeworm in the USA in 1985 was estimated to be over US$1.5 billion.

The reasons are:
*The group of people who have increased susceptibility to foodborne illness is increasing, such as children under 5 years of age, the elderly, the immunocompromised and the malnourished.

*Changing of lifestyle which resulted changes of eating habit: More people eat out, more people rely on processed foods for fast meal, increased mass production of food, and tourism sector so that people are exposed food borne hazard from other place.

Increasing consumption of fresh fruits and vegetables in a number of countries, dining in restaurants and salad bars which relatively rare 50 years ago, they today a major source of food consumption. As a result an increasing number of outbreaks are associated with food prepared outside the home.

*Another aspect the increase in urban populations and decline rural communities. This development has caused fundamental changes in food consumption patterns, food processing, and even food hazards.

*Emerging pathogens – frequent outbreaks caused by new pathogens or the use of antibiotics.
*New technologies and processing methods – other chemicals hazards, such as naturally occurring toxicants, may arise at various points during food production, harvest, processing and preparations.
Effect on economy productivities by foodborne disease

Cost of Illness due to Food Safety Issue

2011-09-01T20:52:00.000-07:00

The first attempts by economists to value food safety used an estimate of cost savings as an estimate of the value of saving lives.

The present value of foregone earnings less consumption plus medical expenses was used as the value of cost savings created by safer food.

Food safety risk management will often require an estimate of the cost associated with foodborne illness. In the USA, diseases caused by the major pathogens alone are estimated to cost up to $35 billion annually (1997) in medical cost and lost productivity.

Cost of illness estimates have been used to value food safety in the US, Canada, Great Britain, and Australia.

Medical costs include physician and hospital services, supplies, special procedures unique to treating each foodborne illness.

Medical costs reflect the number of days or treatments of a medical service, the average cost per service and the number of patients receiving such service.

Productivity losses occur when there is a reduction or cessation of work due to premature mortality and morbidity.

Apart from $35 billion cost of illness caused by the major foodborne pathogens, the annual cost of illness due to E. coli 0157 infections in the USA has been estimated at $405 million. This not include costs due to pain and suffering, and expenditure on outbreak investigation.
Cost of Illness due to Food Safety Issue

E coli

2011-08-23T21:07:00.000-07:00

Escherichia coli is a member of the family Enterobacteriaceae and is character used by possession of the enzyme Beta galactosidase and Beta glucuronidase.

It is gram negative bacteria and is easily grown an manipulated, it has become the best studied prokaryotic model organism.

Escherichia coli is a bacterium that lives in human gut. It is one of the simplest and bets understood living things, yet remarkably sophisticated.

It is cells are rod shaped, about 2.5 micrometers long and 0.5 micrometers in diameter.

E. coli has played a vital role in development of recombinant DNA technology.

E. coli lives a life of luxury in the lower intestines of warm blooded animals, including humans.

Once expelled, it lives a life of penury and hazard in water sediment and soil. It is also found in sewage, treated effluents, natural water subject to fecal contamination whether from humans, wild animas or agricultural activity.

Although most of E. coli do not cause gastrointestinal illness, certain groups of E. coli can cause life threatening diarrhea and severe sequence or disability. Some strains of E coli , such as enterohemorrhagic O157:H7, have a demonstrated pathogenicity to humans.

E. coli infections are typically caused by Escherichia coli O157:H7, the most powerful of hundred of strains of the bacterium Escherichia coli.

E. coli O157:H7 is a leading suspect when food borne illness occurs.
E coli

Shigellosis by Shigella dysenteriae

2011-08-17T20:46:00.000-07:00

Shigellosis is endemic throughout the world and hyperendemic in developing countries. Shigella dysenteriae and Shigella flexneri are most common in developing countries.

Shigella dysenteriae is honored to the Japanese microbiologist, Kiyoshi Shiga, who isolated it from patients with dysentery during a particular severe epidemic in Japan.

The disease results from growth of Shigella spp. in the epithelial cells of the colon. Invaded cells die and the infection spreads to adjacent cells. The result is ulceration, inflammation and bleeding.

Complications may be seen in patients with Shigella dysenteriae Type 1 infections including, conjunctivitis, toxic neuritis, arthritis, haemolytic uraemic syndrome, seizures, sepsis and toxic megacolon.

Shigella dysenteriae are fatal and available in areas where public health facilities and sanitation are poor. Shigella dysenteriae Type 1 remains the most virulence of the shigellae. It is type principle species involved in major epidemics.

Shigella dysenteriae Type 1 is the only member of the various Shigella species that make Shiga toxin that has neurotoxic properties. This chromosomally encoded toxin homologous to Shiga toxin- producing E. coli. Patients infected with Shigella dysenteriae Type 1 are at risk of developing hemolytic uremic syndrome which carries a mortality rate of around 10%.
Shigellosis by Shigella dysenteriae

Nutritional Factors for Microorganism Growth

2011-07-23T21:08:00.000-07:00

Microorganism , especially bacteria, vary greatly in nutritional requirements from species to species.

Nutrition supplies the basic cell building requirements. Nutrition not only provides energy but also acts as precursor for growth of microorganism.

Some microbes have an unconditional need for preformed complex organic compounds while others can thrive with just a few inorganic substance as their sole nutritional requirements.

Some bacteria can utilize the nitrogen in air to form proteins and carbon dioxide in air to obtain energy or to form compounds from which they can then obtain energy.

Others can utilities simple inorganic, such as nitrates, as a source of nitrogen and relatively simple organic compounds such as lactates, as a source of energy.

Most of microbial species utilize simple monomeric substrates such as monosaccharides and amino acids, whereas others digest complex proteins and polysaccharides.

In nature, microbial populations are capable of growth on a variety of substrates.

Nearly all yeast can derive all their nitrogen from lysine, and amino acid.

Some bacteria may require complex organic compounds for growth, including amino acids, vitamin and traces of certain minerals.

Molds and yeast like bacteria, may require basic elements – carbon, hydrogen, nitrogen, phosphorous, sulphur, oxygen and other metal ions as well as vitamin and other organic compound.

Carbon is the prime requirement of any organism Based on the source of carbon, microorganisms can be either autotrophs or heterotrophs. Autotrophs use carbon dioxide of the atmosphere as their source of carbon.
Nutritional Factors for Microorganism Growth

Bacillus cereus Food Poisoning

2011-07-15T05:46:00.000-07:00

Bacillus cereus is a gram positive, spore forming, motile, aerobic rod that also grows well anaerobically.

Bacillus cereus like Clostridium perfringes is present in the environment and requires large numbers of bacterial cells to cause infection.

Bacillus cereus has been known to be cause of food poisoning since the early 1950s.

It has two major strains: one causes diarrhea within six to fifteen hours of consumption of tainted food; the other ‘emetic syndrome’ causes nausea and vomiting within a half hour to six hours after ingestion.

The diarrheal type is often misdiagnosed as C. perfringes and the type that causes nausea and vomiting is often mistaken as Staphylococcus aureus infection.

The diarrheal type of food poisoning is caused by complex enterotoxin during vegetative growth of Bacillus cereus in the small intestine.

While the other one emetic toxin is preformed during the growth of cells in the foods. Diarrhea is not a predominant feature in this type of illness.

A wide variety of foods can harbor the bacteria.

The diarrheal type favors meats, milk, vegetables and fish, while the vomiting type illness is most often associated with rice products such as fried rice, but it can also occur in starchy foods like potatoes, pasta and casseroles.

The diarrheagenic toxin is inactivated by heating for 5 min at 50 degree C, although its thermostabiltiy is reported to be greater.

Both types of illness are generally not serious, except in young children, older adults and others who are immune compromised and may not have the stamina to combat the associated dehydration.

Recovery for Bacillus cereus food poisoning is normally within 24 hours, with no complications.
Bacillus cereus Food Poisoning

Food Infection: Yersinia enterocolitica

2011-07-14T21:39:00.000-07:00

Yersinia enterocolitis is most often associated with pork precuts and milk, because food borne outbreaks are often linked to these foods. However, the organism has been isolated from other foods such as fruits, vegetables, dairy products, various meats and poultry, oysters, fish, salads, sandwich, pastries and tofu. Poor sanitation and improper sterilization techniques by food handlers, including improper storage, cannot be overlooked as contributing to contamination.

Yersinia species are gram positive, non-spore forming, and facultatively anaerobic. The genus Yersinia belongs to the family Enterobacteriaceae. Three of the seven species are pathogenic to humans: Y. pestis, Y, enterocolitica and Y. pseudotuberculosis.

Yersinia pseudotuberculosis causes an illness similar to Yersinia enterocolitica, and Yersinia pestis, which causes plague. Only a few strains of Yersinia enterocolitica cause illness in humans.

Yesinia is an important cause of gastroenteritis in humans, especially in temperate countries.

The consequences of yersiniosis are severe, and include prolonged acute infections, pseudoappendicits, and long term sequelae such as reactive arthritis and erythema nodosum.

Common symptoms in children are fever, abdominal pain, and diarrhea, which is often bloody. Symptoms typically develop 4 to 7 days after exposure and may last 1 to 3 weeks or longer.

Acute Yersinia enterocolitica infections produce severe diarrhea in humans, along with Peyer's patch necrosis, chronic lymphadenopathy, and hepatic or splenic abscesses.

The most effective controls of Yersinia contamination include the following: proper cooking and refrigeration, purification of water, pasteurization of dairy products, separation of cooked and uncooked foods, sanitation of food preparation surfaces with at least 1% bleach solution, washing of vegetables and cooking foods to 120 degree C – 170 degree C.

Yersinia enterocolitica proliferates readily at refrigeration temperatures. Hence, refrigeration does not effectively control the growth.
Food Infection: Yersinia enterocolitica

Bovine Spongiform Encephalopathy

2011-07-01T18:50:00.000-07:00

Bovine spongiform encephalopathy or mad cow disease is a fatal brain disease of cattle. The brain of affected animals appears sponge-like under a microscope.

Bovine Spongiform Encephalopathy is of great importance because:
*Its causative agent can overcome the species barrier and became very dangerous to man
*Cattle are significant source of human food, and an undiagnosed Bovine Spongiform Encephalopathy infection is a danger to man.

The first appeared in the United Kingdom in 1986. Scientists believed the disease may have first been transmitted though feeding cattle protein made from sheep carcasses infected with scrapie, the sheep form of the disease.

In the early 1980s, a change in the manufacturing process that limited steam heat treatment may have played a role in the appearance of the disease.

Bovine Spongiform Encephalopathy developed into an epidemic as a consequence of an intensive farming practice – the recycling of normal protein in ruminant feed.

The human form is Creutzfeldt Jakob disease (CJD). It is a rare disease that occurs in approximately one person per million.

A new type of CJD, new variant or nvCJD has been linked to Bovine spongiform encephalopathy exposure. It is believed that eating Bovine spongiform encephalopathy infected meat can cause variant Creutzfeldt Jakob disease.

For this reason, it is important that cattle are regularly tested for BSE and that contaminated meat is prevented from getting onto food products for human consumption.

The origin, transmission and nature of spongiform encephalopathies theory is that the causative agent is a prion, a type of pathogenic protein.

Prion proteins is a minute proteinaceous infectious particles 4-6 nm in diameter. They occur in normal and pathogenic forms on the surface of nerve cells and various cells of lymphatic tissue.

Infective prions are thought to be found only in the brain tissue, spinal cord and retina of infected animals, not in meat or milk products.
Bovine Spongiform Encephalopathy

Destruction of Salmonella by heat

2011-05-13T18:05:00.001-07:00

Heating process are widely used in the food industry to enhance product quality and safety. Destruction of Salmonella by heat, it should be explained that as they are heated and a temperature is reached at which they are destroyed, they are not all destroyed at once.

Large numbers are destroyed when the heat is first applied, but the death rate quickly drops.

For instance , if at 48.9 degree C, 90% of the organisms would be destroyed in a period of 5 minutes, it would take 10 minutes to kill 99% of the organisms, 15 minutes to kill 99.9% of the organisms and so on.

Salmonella is not a spore forming organism. It is not, therefore, a heating resistant organism; pasteurization and equivalent heat treatments will destroy the organism under normal circumstances.

It should be noted that if some of these Salmonella organisms in foods survive whatever heating they receive during coking, and the food is thereafter held at temperatures at which they will grow 6.7-43.3 degree C, especially at room temperature, the organisms may grow again to large numbers.

When heating foods, it is important that all parts of the foods satisfy this temperature time requirements.

Some types of cooking is not sufficient to destroy all Salmonella bacteria that may be present in foods. Examples of cooked foods in which these organisms may survive are scrambled, boiled, or fried eggs, meringue, turkey stiffing , oyster stew, steamed clams, and some meat dishes.

Salmonella are more heat resistant in yolk than in whole egg due to the lower pH an higher total solids content in the yolk.
Destruction of Salmonella by heat

Salmonella outbreaks in chocolate

2011-04-26T19:28:00.000-07:00

It was not often realized that salmonella can persists in chocolate. Salmonella survives in chocolate for years.

In the mid 1970s there were more than 200 cases in Canada and the United States; these were mainly in young children and were caused by the relatively rare Salmonella eastbourne.

This serotype was found to be isolated in chocolate up to 15 months after manufacturers.

In 1982, 269 patients were found to have Salmonella napoli in their feces in comparison to only 15 reported cases in the previous thirty years.

Salmonella napoli named after its Italian origin.

Due to increase in reports of Salmonella napoli, it was controlled by removing a make of imported chocolate from the food chain.

Imported chocolate bars contaminated with Salmonella napoli were distributed to many parts of the country and cases were reported with no clear relationship either in time or place until careful epidemiology suggested the likely means of transmission.
Salmonella outbreaks in chocolate

Foodborne illness caused by cross contamination

2011-04-13T19:11:00.000-07:00

Food borne illness refers to illness caused by the ingestion of contaminated food and beverages. Foodborne illness can be caused by either an infection or an intoxication.

Cross contamination is one of the major causes of foodborne illness and can easily occur during preparation.

The contamination of food by bacteria that occurs when the food comes into contact with surfaces previously touched by raw meat, poultry or seafood.

Cross contamination occurs when a bacteria that’s present in one food accidently spreads to another food, usually through improper handling and storage.

For example, Compylobacter jejuni are very common cause of food borne illness. This pathogen is associated with raw poultry an sometimes raw milk. Illness are often caused when cross-contamination between these source and ready to eat foods, such as salads, occurs during food preparation.

The major cause of food borne illness is unsanitary food handling. To reduce risk of contamination, proper personal hygiene and hand washing must be practiced by all food handlers. Steps must be taken to prevent cross contamination between raw and cooked foods and though food handlers.

Cross contamination can be avoided by:
*Preventing raw and cooked foods touching each other. Never mixed food products when restocking.
*Preventing blood and juices from raw foods dripping onto cooked foods
*Preventing bacteria from being transferred on hands, knives, utensils, chopping boards or work surfaces.
*Properly clean and sanitize utensils, equipment and surfaces.
*Clean and sanitize work areas.

Foodborne illness caused by cross contamination

Protozoa and Parasites

2011-03-15T03:45:00.000-07:00

Some protozoa also cause foodborne illness. Parasites must live on or inside a living host to survive. The most common foodborne parasites are Anisakis simplex, Cryptosporidium parvum, Toxoplasma gondii, Giardia lamblia, and Cyclospora cayetanensis.

Cyclospora was not known to cause human sickness until 1979, when the first cases were reported. Since then fresh produce has been associated with several outbreaks of food borne illness from Cyclospora in US and Canada, cases prolonged gastrointestinal disease in travelers and expatriates associated with southeast Asia and the rise of the immunocompromised population.

Giardia has been identified more than any other pathogen in waterborne disease outbreaks, but there also have been foodborne Giardia outbreaks.

Giardia was first describe by Lambl, who it the name intestinalis. Dogs pick up giardia by drinking water from streams and lakes or other contaminated sources. A person can contract giardia the same way or by failing to wash their hands after cleaning up after a Giardia infected dogs.

Cryptosporidium is also primarily a waterborne pathogen. An estimated 21 percent of waterborne outbreaks from drinking water are due to parasitic agents mainly Giardia and Cryptosporidium.

Waterborne Cryptosporidium oocysts can originate from cattle, swine, horses, deer, chicken, ducks, fish, turtles, guinea pigs, cats dogs or domestic sewage discharge.

Toxoplasma gondii is common in warm blooded animals, including cats, rats, pigs, cows, sheep, deer, chickens and birds.

It can be found in feces and raw meat from these animals.

Anisakis simplex and related worms are found in raw or undercooked seafood. These nematodes parasitizes fish and sea mammals, and thus humans ingest them by eating raw, pickled or smoked fish.

The most common clinical manifestations are those of acute gastric anisakiasis, characterized by epigastric pain, chills, nausea and vomiting within 12-24 of ingestion of parasitized food.

Trichinosis, caused by the parasitic worn Trichinella spiralis and associated with eating undercooked pork, is now relatively rare in the United States.

The parasites has a very broad host range; the major source of human infection are pork or bear meat.

Human infection can vary form subclinical (the majority of cases) to fatal.
Protozoa and Parasites

Background of Clostridium perfringes

2011-03-01T19:43:00.000-08:00

Clostridium perfringes is an aerobic bacteria present in the environment and in the intestines of both humans and domestic and feral animals.

Clostridium perfringes was first described by Welch and Nuttall in 1892 after they had isolated the organism from a cadaver.

Since the bacteria are so prevalent, most foods are contaminated with, especially animal proteins such as meat.

However, it takes millions of bacterial cells to cause illness. Bacterial cells double every twenty to thirty minutes so a single bacterium can reach over a trillion cells in twenty four hours if the conditions are favorable.

The small amounts of C. perfringes in foods do not cause any problems unless if it is prepared too long before serving.

Outbreaks occur most commonly in institutional setting like hospitals, school, cafeteria, prisons and nursing homes where food is prepared several hours before serving.

Clostridium perfringes is group into five types based on the production and secretion of four major toxin.

Clostridium perfringes produces a number of other virulence enhancing toxins and hydrolytic enzymes. The most significant of these is probably enterotoxin.

In food poisoning outbreaks, demonstration of hundred of thousands more organisms per gram is a suspect food supports a diagnosis of perfringes poisoning when substantiated by clinical and epidemiological evidence.

Clostridium perfringes type A causes one of the most common food borne illness in the United States. The characteristic diarrhea and abdominal cramps associated with C. perfringes food poisoning are caused by a protein enterotoxin, Clostridium perfringes enterotoxin, CPE (2-4).
Background of Clostridium perfringes

Microbial Grouping

2011-02-04T09:33:00.000-08:00

Microbial Grouping
The microbial groups important in foods consist of several species and types of bacteria, yeasts, molds and viruses. Bacteria, yeasts, molds and viruses are important in food for their ability to cause foodborne diseases and food spoilage to produce food and food ingredients.

Many bacterial species and some molds and viruses, but not yeasts are able to cause foodborne disease.

Most bacteria, molds and yeasts, because of their ability to grow in foods (viruses cannot grow in foods, can potentially cause food spoilage.

Several species of bacteria, molds and yeasts are considered safe of food grade or both and are used to produce fermented foods and food ingredients.

Among the four major groups, bacteria constitute the largest group. Because of their ubiquitous presence and rapid growth rate even under condition where yeast and molds cannot grow, they are considered the most important in food spoilage and foodborne disease.

Prion or proteinaceous infectious a particles have been identified to cause transmissible spongiform encephalopathies (TSEs) in humans and animals.
Microbial Grouping

Aflatoxins effects on Health

2011-01-26T08:34:00.000-08:00

Aflatoxins effects on Health
At high enough exposure levels, alflatoxins can cause acute toxicity, and potentially death in mammals, birds and fish as well as in humans.

The liver is the principal organ affected it high levels of aflatoxins have also been found in the lungs, kidneys, brains and hearts of individuals dying of acute aflatoxicosis.

Acute necrosis and cirrhosis of the liver is typical , ailing with hemorrhaging and oedema.

LD50 (lethal dose) values for animals vary between 0.5 and 10 mg/kg bodyweight.

Chronic toxicity is probably more important from a food safety point of view, certainly in more developed regions of the world. Aflatoxin B1 is a very potent carcinogen and a mutagen in many animals and therefore potentially in humans, and the liver is again the main target organ.

Ingestion of low levels over a long period has been implicated in primary liver cancer, chronic hepatitis, jaundice, cirrhoses and impaired nutrient conversion.

Aflatoxins may also play a role in other conditions, such as Reye’s syndromes and kwashiorkor (a childhood condition linked to malnutrition).

Less is known about the chronic toxicity of aflatoxin G1 and M1, but these are also thought to be carcinogens, though probably a little less potent than B1.

Little is known about the level of dietary exposure to aflatoxins necessary to affect health, especially in humans, and diagnosis of chronic toxicity is very difficult.

It is generally agreed that the best approach is to minimize the levels in all foods as far as is technically possible and to assume that any dietary exposure is undesirable.’
Aflatoxins effects on Health

Favorable growth conditions for bacteria

2011-01-15T21:04:00.000-08:00

Favorable growth conditions for bacteria
Microorganisms grow when they have the right nutrients and conditions for growth. Bacteria need these conditions to grow:
Food
High protein foods are often contaminated at the time of purchase. Using safe food practices destroys the bacteria. Acidity: bacteria prefer low-acid environments. Some bacteria do survive an acidic environment.

Bacteria use an enormous range include various sugars and either carbohydrates, amino acids, sterols, alcohols, hydrocarbons, inorganic salts and carbon dioxide.

Time
Potentially hazardous foods should not remain in the danger zone for more than four hours during the entire food handling process.

Temperature
The temperature danger zone is 40 degrees F to 140 degrees F.

Oxygen
Many bacteria grow bets in the present of oxygen (aerobic organism). Some bacteria grow without oxygen- anaerobic. However, both types of bacteria cause foodborne illness.

Others grow equally well under either aerobic or anaerobic conditions.

Moisture
Bacteria grow best in a moist environment.
A high proportion of the mass of a bacterium is water, and during growth, nutrients and waste products enter and leave the cell. Bacteria can grow only in or on materials which have adequate free or available water.

pH
Most bacteria grow best at near pH7 (neutral), and the majority cannot grow under strongly acidic or strongly alkaline solution.
Favorable growth conditions for bacteria

Shigella and Yersinia

2010-12-15T23:21:00.000-08:00

Shigella and Yersinia
Shigella
Shigella causes little less than 10 percent of all food borne illness in the United States. It is widespread worldwide and is very virulent: as few as ten cells cause infection.

Shigellosis (the disease caused by Shigella) usually strikes between twelve and fifty hours after the contaminated food is consumed.

It can cause abdominal pain, cramps, diarrhea, fever and vomiting.

On rare occasions it can cause Reiter’s syndrome, reactive arthritis and hemolytic uremic syndrome.

It is often found in prepared salads, raw vegetables, milk, other dairy products and poultry.

Yersinia
There are three pathogenic species of Yersinia. Y. pestis causes the plaque and is not transmitted through food. Y. enterocolitica and Y. pseudotuberculosis cause gastrointestinal problems, including abdominal pain, diarrhea and vomiting.

Yersinia infections often mimic appendicitis and can sometimes result in unnecessary surgery.

The bacteria can also cause infectious in wounds, joints and the urinary tract.

Y. pseudotuberculosis is very rare in the United states but occurs more frequently in Japan, Scandinavia and other parts of northern Europe.

Strains of Y. enterocolitica can be found in meats, including beef, pork, lamb, oyster and fish and also in raw milk.

Although most people recover quickly from yersiniois, about 2 to 3 percent develop reactive arthritis.
Shigella and Yersinia

Intoxication of Bacteria

2010-12-01T04:18:00.000-08:00

Intoxication of Bacteria
Some bacteria produce harmful toxin or other chemicals that are then present in the food. It is not the bug itself that causes illness, but rather the toxin the bacteria produce.

This can happen even if the pathogen itself has been killed as long as it had sufficient time to produce enough toxin before frying.

Staphylococcus aureus is an example of this type of bacteria. Staphylococci exist in air, dust, sewage, milk, animals, humans and on food or on food equipment.

They are present in the nasal passage and throats and on the hair and skin of 5o percent or more of health individuals. Illness is cause by ingesting toxins produced in food by some strains of S. aureus, usually because the food has not been kept hot enough or cold enough.

Although cooking easily destroys the bacteria, the toxin produced by the bacteria very resistant to heating, refrigeration and freezing. It is not possible to detect the presence of the toxin in food by smell, appearance or taste.

The likehood of illness increases with the amount of time the bacteria are left at an improper temperature.
Intoxication of Bacteria

Botulism

2010-11-17T02:41:00.000-08:00

Botulism is a rare but serious illness caused by Botulism toxin (poison) produced by Clostridium Botulism bacteria.

The name botulism is derived from the Latin term ‘botulus’ for sausage.

The first botulism outbreak historian know of occurred in 1793 in the town of Wildbad, Germany. Thirteen people shared a meal of blood sausage, soon became very sick, vomited, their speech thickened, some of them partially paralyzed. At the end six people died.

Hundred years later in 1895 in Ellezelles, Belgium, among a group of amateur musicians, thirty four people became sick and three died as a result of this outbreak.

This toxin affects the nerves and if untreated, can cause paralysis and respiratory failure.

There are three main kinds of botulism:
*Food borne botulism is caused by eating foods that contain the botulism toxin
*Wound botulism is caused by toxin produced from a wound infected with Clostridium botulism
*Infant botulism is caused by consuming the spires of the botulinum bacteria, which then grow in the intestines and release toxin.

U.S. health care providers report an average of 110 cases of food, infant, and wound Botulism to CDC each year with about 10 to 30 outbreaks of food-borne Botulism reported every year.

Although this illness does not occur frequently, it can be fatal if not treated quickly and properly. Food borne botulism can be especially dangerous because many people can be poisoned by eating a contaminated food.

Transmission of C. botulism: often, cases of food-borne Botulism come from home-canned foods with low acid content, such as asparagus, green beans, beets, and corn.

Clostridium botulism is anaerobic, which means it can survive and grow with little or no oxygen.

Therefore, it can survive very well in sealed containers. Unusual sources, Chili peppers, tomatoes and improperly handled baked potatoes wrapped in aluminum foil are unusual sources that often cause outbreaks of this disease.

It is spore-forming organism that elaborates a neurotoxin that prevents the release of acetylcholine.

Illness developed after toxin exposure, and patients present with a symmetric descending paralysis that characteristically begins with dysarthria, diplopia, dysphonia or dysphagia.

What are the most common neurologic symptoms of food borne Botulism?
• Double vision and drooping eyelids
• Slurred speech
• Dry mouth and difficulty swallowing
• Weak muscles are symptoms in including muscle of respiration.

These symptoms can easily be confused and over looked as food poisoning in older people or children.

Symptoms of food borne Botulism usually begin within 18 to 36 hours after eating contaminated food, but can occur in as few as 6 hours or as much as 10 days afterward.

Patients developing severe botulism experience breathing failure, paralysis. The treatment for advanced cases is ventilators or breathing machines.

Every case of botulism is considered a public health emergency. If there suspected case of botulism, the local state health department should be notified.
Botulism

Escherichia coli

2010-11-01T00:27:00.000-07:00

Escherichia coli
Escherichia coli is a type of bacteria that thrives in our intestines and helps digest food. Most strains are beneficial, but a few release harmful toxins that can cause great discomfort and even death.

There are four classes of Escherichia coli that cause illness in humans: enteroinvasive, enteropathogenic, enterotoxigenic, and the most toxic, 0157:H7.

Enteropathogenic E. coli primarily strikes infants and causes bloody or watery diarrhea. It affects bottle-fed infants more often than breast-fed babies and occurs most frequently in less developed countries with inadequate accesses to safe drinking water.

It can have a mortality rate of 50 percent in countries where adequate medical treatment is unavailable.

Enteroinvasive E. coli is a highly potent strain of E. coli with an infective dose of as few as ten microorganisms.

The organisms invade the cells lining the intestine and cause dysentery. Symptoms include blood and mucous in in the stool, abdominal cramps, diarrhea vomiting, fever, chills and malaise.

Although the infection usually only lasts twelve to seventy two hours, occasionally it can lead to hemolytic uremic syndrome.

It can occur in hamburger and dairy products but one cruse ship outbreak was attributed to potato salad.

Enterotoxigenic E. coli causes gastroenteritis or “traveler’s diarrhea.” It occurs in infants in less developed countries and travelers from industrialized countries.

This strain has symptoms of watery diarrhea, abdominal cramps, low grade fever, nausea and malaise.

It the quite a large dose to produce illness. Approximately 100 million to 10 billion individual bacteria are required.
Escherichia coli

Foodborne Disease Incidence

2010-10-04T07:34:00.000-07:00

Accurate estimates of the yearly incidence of foodborne disease are difficult and sometimes impossible, depending on the reporting systems in different countries.

Many countries have no system for collecting and reporting data on gastrointestinal infections and even where these exists the reported data is acknowledged to represent only a fraction of the true number of cases.

The true incidence of food borne infection is also difficult to determine since asymptomatic infection is common, because only a minority of people will seek medical treatment and because only a minority of patients will be investigated microbiologically.

Food borne disease statistics in some European countries and the Americas, where reporting systems are netter than some other regions, are dominated by cases of salmonellosis and campylobacteriosis.

While in other regions, however, foodborne disease statistics tend to rely on outbreak information only, and in some cases, other organism, are identified as leading causes of illness.

For example in Australia, of the 17,2 million cases of gastroenteritis each year in Australia, there are 5.4 million cases that are conservatively estimated to be due to contaminated food resulting in the loss of 6.5 million days of paid work.

In the US, it has been estimated that foodborne disease cause approximately 78 millions illnesses, 325,000 hospitalization and 5000 deaths each year, with known pathogens accounting for 14 millions illness, 60,000 hospitalizations and 1800 deaths.

The organism identified as causing the largest number of foodborne related cases of illness were Norwalk-like virus, followed by campylobacter, salmonellas, Clostridium perfringes, Giardia lamblia, staphylococci, Escherichia coli, and Toxoplasma gondii, respectively.

A number of well publicized outbreaks of food borne illness and recalls of meat and meat products have occurred during the past decade.

Many million of kilograms of ground beef and luncheon meat have been recalled because of potential contamination with E. coli o157:H7 and Listeria monocytogenes, respectively.

A large outbreak in the early 1990s due to E. coli O157:H7 contaminated hamburgers resulted in four deaths and hundred of illnesses.
Foodborne Disease Incidence

Viruses in Foodborne Diseases

2010-08-09T06:19:00.001-07:00

Viruses in Foodborne Diseases
Several viruses also cause foodborne illness. Viruses differ from bacteria in that they are smaller, require a living animal or human host to grow and reproduce, do not multiply in foods and are not complete cells.

Viruses belonging to at least 10 families have been associated with foodborne illness, causing various disease.

These range for self-limiting diarrheal disease to severe liver disease leading to hospitalization. The best estimates of the burden of foodborne disease associated with viruses are available for viruses causing gastroenteritis and infectious intestinal diseases.

Ingestion of only a few viral particles is enough to produce an infection.

Humans are host to a number of viruses that to reproduce in the intestines and then are excreted in the feces.

Thus, transmission of viruses comes from contact with sewerage or water contaminated by fecal matter or direct contact with human fecal material.

Raw or uncooked molluscan shellfish (oyster, clams, mussels and scallops) are the food most often associated with foodborne viral diseases.

Human pathogenic viruses are often discharge into marine waters through treated and untreated sewage.

As shellfish filter contaminants from these polluted waters, they store them within their edible tissues.

Shellfish grown and harvested from polluted waters have been implicated in outbreaks of viral diseases.

The other main source of transmission is from infected food workers who have poor personal hygiene.

Therefore, proper hand washing and using a clean water supply are vital to controlling the spread of foodborne viruses.

Hepatitis A is a virus commonly associated with foodborne infections. The incubation period for hepatitis A, before a person develops an symptoms, is anywhere from 10 to 50 days.

It is during this period before symptoms appear that a carrier is most infectious and most likely to spread the disease.

Hepatitis A and many other viral and bacterial pathogens, is most often transmitted via a fecal oral route.

The fact that a person is infectious even before they know they have the disease makes it difficult to control.
Viruses in Foodborne Diseases

The Size of Microbes

2010-08-03T11:26:00.000-07:00

The Size of Microbes
Bacteria are comparatively small. The single cell of many bacteria is about 40 millionth of an inch (1 u) in diameter.

There are however, some types of bacteria that may be 50 or more times larger than this.

Due to their small size, bacteria cannot be seen with naked eye, and when evidence of their growth can be seen, such as when slime forms on meat, the organisms will have multiplied to a very large numbers, billions of cells square inch of the meat surface.

The single cells of the mold, although not visible without magnification, is much larger than the single bacterial cell, and any significant growth of molds on foods can be seen.

The visible mold comprises mycelia with or without spore heads.

The spore head carries the spore that will give rise to more growth.

Yeasts vary in size from that of the more common spherical bacteria to a form several times larger than this.

Like bacteria when grow in solution, the individual cells cannot be seen, but eventually, the cell numbers will accumulate to the point where the solution becomes cloudy. There are however, some instances on which groups of cells will, form visible (colonies) on foods or on the surface of solutions.
The Size of Microbes