UNIT 5 - FOOD BORNE DISEASES

Foodborne disease: A disease caused by consuming contaminated food or drink. Myriad microbes and toxic substances can contaminate foods. There are more than 250 known foodborne diseases. The majority are infectious and are caused by bacteria, viruses, and parasites.

Foodborne illness (also foodborne disease and colloquially referred to as food poisoning) is any illness resulting from the food spoilage of contaminated food, pathogenic bacteria, viruses, or parasites that contaminate food, as well as toxins such as poisonous mushrooms and various species of beans that have not been boiled for at least 10 minutes.

Campylobacter and Salmonella species account for over 90% of all reported  cases of bacteria related to food poisoning worldwide.

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Causes

Foodborne disease usually arises from improper handling, preparation, or food storage. Good hygiene practices before, during, and after food preparation can reduce the chances of contracting an illness. There is a consensus in the public health community that regular hand-washing is one of the most effective defenses against the spread of foodborne illness. The action of monitoring food to ensure that it will not cause foodborne illness is known as food safety.

Foodborne disease can also be caused by a large variety of toxins that affect the environment.

Furthermore, foodborne illness can be caused by pesticides or medicines in food and natural toxic substances such as poisonous mushrooms or reef fish.

Bacteria

Bacteria are a common cause of foodborne illness.

Most common bacterial foodborne pathogens are:

Bacteria : Clostridium Botulinum

Anaerobic bacteria

Organism produce a neurotoxin,

Type of illness: Bacterial intoxication

Onset time : 12-36 hrs.

Symptoms : Dizziness , double vision,  difficulty in breathing and swallowing

Food Sources : Improperly canned foods, vacuum packed, Refrigerated foods

Bacteria : Escherichia coli

Produce Shiga Toxin , a poisonous substance

Facultative anaerobic bacteria

Type of Illness : Bacterial Infection

Onset time : 3-8 days

Symptoms : Bloody diarrhea followed by kidney failure

Food Sources : undercooked ground beef, unpasteurized apple juice  undercooked fruits and vegetables, raw milk, dairy products

Bacteria : Listeria Monocytogenes

Facultative anaerobic bacteria
Ability to survive in high salt foods, and can grow at refrigerated temperature.
Type of Illness : Bacterial Infection
Onset time : 3- 70 days
Symptoms : headache, stiff neck, confusion, loss of balance, dangerous for pregnant
Food Sources: Raw milk, meat, refrigerated ready to eat foods ,soft cheeses.

Bacteria : Staphylococcus aureus
Facultative anaerobic bacteria. Can grow in cooked or safe foods that are re-contaminated
Commonly found in human skin, hands, hair, nose and throat.
Can grow in high salt or high sugar, and lower water activity
Type of Illness : Bacterial intoxication
Symptoms : nausea, vomiting, abdominal cramps, headaches
Food Sources: Foods that are prepared by human contacts, Left overmeat,  eggs, egg products, potato salad, salad dressings.

Bacteria : Shigella bacteria

Facultative anaerobic bacteria

Comes from human intestines, polluted water, spread by flies and food handlers

Type of Illness : Bacterial infection

Symptoms : Diarrhea, fever, abdominal cramps, dehydration

Food Sources : foods that are prepared by human contacts, salads,  ready to eat meats pasta salads, lettuce etc.

Bacteria: Vibrio cholerae

Cholera is an infectious disease that causes severe watery diarrhea, which can lead to dehydration and even death if untreated. It is caused by eating food or drinking water contaminated with a bacterium called Vibrio cholerae.

Most commonly associated with cholera is seafood, both molluscan shellfish and crustaceans. Seafood may be contaminated in its natural environment or during preparation. Other food items associated with outbreaks are fruit and vegetables, meat, cooked grains, etc.

Viruses

Viral infections make up perhaps one-third of cases of food poisoning in developed countries. Foodborne viral infection are usually of intermediate (1–3 days) incubation period, causing illnesses which are self-limited in otherwise healthy individuals; they are similar to the bacterial forms described above.

Hepatitis A
Virus : Hepto Virus or a Hepatitis A virus
Found in human intestinal and urinary tract and contaminated water

Symptoms : Fever, fatigue, headache, nausea, stomach pain, vomiting, “jaundice”

Incubation time: 2-10 months after contaminated food and water is consumed


Food sources : Oyster, raw vegetables

Norwalk Virus
Virus : Norwalk virus
Symptoms : Nausea, vomiting, diarrhea, abdominal pain, headache, low grade fever

Food Sources : Contaminated water, shellfish from contaminated water, contaminated

fruits and vegetables

Rota Virus
Virus : Cause diseases like rota virus gastroenteritis
It is the leading cause of severe diarrhea among  infants and children.

Symptoms : vomiting, low grade fever,
watery diarrhea

Transmission : person to person spread  through contaminated hands

FUNGI

Molds
Individual mold cells are microscopic, they grew quickly and they become visible
Molds spoil foods, causing discoloration, and unpleasant smell
Mold produce toxins, some of which relate to cancer and cause allergies
Aflatoxin can cause liver disease
Although the cells and spores can be killed by heating to 140°F for 10 minutes, the toxins are heat stable and are not destroyed

Yeast
Like molds, yeast can cause food spoilage
Foods such as jellies, honey, syrup, fruit juices are most likely loved by yeast
Evidence of bubbles, and alcoholic smell or taste are the sign where foods have the  presence of yeast

Discard any foods that has the evidence of yeast

DISEASE CAUSED BY PARASITES

Cyclosporiasis
Parasite : Cyclospora cayetanisis
Symptoms : infections that infect the small intestines, Watery diarrhea, Loss of appetite ,  Bloating, Stomach cramps , Nausea , Vomiting , Low grade fever

Food Sources : Berries, lettuce, fresh herbs

Giardiasis
Parasite: Giardia doudenalis

A single cell microorganism called “protozoa
Symptoms: diarrhea, stomach cramps, nausea

Food Sources: undercooked pork

Trichonosis

Parasite : Trichiniella spiralis

This parasite looks like a small, hairy round worm

Symptoms :Nausea, vomiting, abdominal pain, later stage are fever, swelling of tissues

around the eyes, muscle stiffness, death

Food Sources: Undercooked pork and sausages, Ground meats contaminated  through meat grinders

DISEASE CAUSED BY TOXIN

Definition :

Toxin are toxicants or poisonous substance or produced by living organism and  generally not well defined  chemically.

SOME ORGANISMS & THEIR TOXINS

Organism	Toxin
Bacteria	Botulinum toxin, Staphylococcus toxin
Fungi	Afalatoxin, Mycotoxin, Ochratoxin, Patulin
Toxic algae	Okadaic acid
Natural toxins	Histamine, Glycoalcoloids

TOXIN CHARACTERISTICS

    Non replicative (Most are proteinaceous)
Non transmittable (human to human)
Nonvolatile
Colorless
Odorless
Tasteless
Most are stable at standard conditions

Aflatoxin

Agent: Aspergillus flavus

Afalatoxin B1, B2, G1, G2 (B1 is the most common) 

Toxicity: 0.5-10 mg/kg 

Diseases: Liver cancer, chronic hepatitis, jaundice, cirrhosis.

Cause acute toxicity, and potentially death 

Food sources: Peanuts and peanut butter, tree nuts such as pecans corn,  wheat oil seeds such as cottonseed .

Ochratoxin

Agent: Aspergillus ochraceus

Toxicity: No documented acute toxicity in humans.

Food sources: Soy beans, coffee beans, grapes, peanuts, cereals .

Patulin

Agent: Aspergillus clavatus, Penicillium expansum

Provisional maximum tolerable daily intake 0.4μg/kg 

Relatively heat stable and not destroyed by pasteurization

Toxicity: No documented acute toxicity.

Food sources : Apple and apple juice, Pears, grapes, bilberries may affect, Sweet cider

PREVENTIVE MEASURES: FOOD BORNE DISEASE

Food safety is extremely important to prevent food-borne illness.

Food-borne illnesses can cause a variety of symptoms. For small children, older adults, and people with weakened immune systems, symptoms can be severe and even life-threatening.

The cause of most food-borne illness is bacteria. Some of these bacteria are E. coli, salmonella, Staphylococcus aureus, and Clostridium botulinum.

You can prevent most food-borne illnesses when you know and use proper ways to handle, store, and prepare food.

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Buy and Store Food Safely

• Do not buy food in damaged packages or cans.
• Look for expiration dates on food packages. Do not buy outdated foods.
• Buy only pasteurized milk, cheese, ciders, and juices.
• Keep raw meat, poultry, and fish in a separate shopping bag. This prevents the juice from dripping onto other food.
• Place perishable foods in the refrigerator or freezer right away after grocery shopping.

Prepare Food Safely

• Wash your hands with hot soapy water before and after you prepare foods.
• Thaw food in the refrigerator or microwave oven, not on the kitchen counter.
• If possible, have 2 cutting boards. Use 1 cutting board for raw meat, poultry, and seafood, and use the other cutting board or fresh fruits and vegetables.If you have only 1 cutting board, prepare fruits and vegetables first, and put them safely out of the way. Wash the cutting board very well with soap and hot water. Then prepare the raw meat, poultry, or seafood. When finished, wash the cutting board again.
• Cook foods thoroughly to kill harmful bacteria.
• Use a thermometer to check that meat and poultry are completely cooked. Cook to an internal temperature of:
  • • At least 145 F for roasts and steaks
    • 180 F for whole poultry
    • At least 160 F for ground beef
• Cook fish until it is opaque and flakes easily with a fork.
• Cook eggs until the white and yolk are firm.

Store Leftover Food Safely

• Keep hot foods hot and cold foods cold. For a cold food like pudding, do not let it sit out at room temperature — keep it cold in the refrigerator. When a roast turkey is done, do not store it on the countertop at room temperature — keep it hot (or freeze or refrigerate leftovers). Remember: This rule also applies to foods packed for lunches, picnics, and camping.
• Keep your refrigerator temperature at 40 F to 45 F. Keep your freezer at 0 F.
• Refrigerate leftovers as soon as possible.
• For quick cooling in the refrigerator or freezer, divide large portions of leftovers into small bags or containers.
• Date leftovers, and use them within 3 to 5 days.
• Leftovers should be reheated to 165 F.

Food Storage Times

Safe storage times for refrigerator and freezer are suggested in the list of foods below:

Food Stored	Refrigerator Time	Freezer Time
Meat (raw)	3 to 5 days	6 to 12 months
Meat (cooked)	3 to 4 days	2 to 3 months
Ground meats (raw)	1 to 2 days	3 to 4 months
Ground meats (cooked)	3 to 4 days	2 to 3 months
Poultry (raw)	1 to 2 days	9 months (parts) 1 year (whole)
Poultry (cooked)	3 to 4 days	4 to 6 months
Lunch meats (open package)	3 to 5 days	1 to 2 months (freezer wrap)
Fish (raw)	1 to 2 days	Up to 6 months
Fish (cooked)	3 to 4 days	4 to 6 months
Eggs in shell (raw)	4 to 5 weeks	Do not freeze
Eggs in shell (hard cooked)	1 week	Do not freeze
Milk	A few days past “sell by” date	Do not freeze
Cheese (hard, semi-hard)	3 to 4 weeks	Can freeze (changes taste and texture)

• DO NOT leave perishable, cooked food at room temperature longer than 2 hours.
• Remove the stuffing from poultry and meat. Refrigerate them in separate containers.
• To be safe, discard moldy food.