What Is Food Borne Hazards

In recent years, a number of bacteria, viruses and parasites have emerged as
food-borne pathogens resulting in numerous food-borne disease outbreaks.
Genetic changes in microorganisms resulting in increased virulence, changes
in social attitudes and eating habits, changes in food production and
distribution systems and demographic shifts are some of the factors responsible
for this.

What Is Food Borne Hazards

Microbial Infections

Bacillus cereus

Bacillus cereus is a Gram-positive, motile, spore -forming, facultative
anaerobic rod. It is ubiquitous in nature, commonly found in soil (especially
rice, paddy, soil) and vegetation. 
It has been isolated from many foods,
including cereal and cereal derivatives, spices, milk and dairy products, vanilla
sauce, recipe dishes, chicken soup, mashed potatoes, vegetables, rice dishes
and dried foods.
Bacillus cereus can cause two distinctive forms of food poisoning caused by
enterotoxins. Emetic food poisoning is caused by the ingestion of emetic toxin
that has been pre-formed in food. It causes general malaise, nausea and
vomiting and occasionally diarrhoea. 
This type of food poisoning has been
linked with starchy foods such as cooked rice, pasta and noodles. Diarrhoeal food poisoning is caused from the formation and release of enterotoxin in the
small intestine. However, the enterotoxin can also be pre-formed in food.

Clostridium botulinum

Clostridium botulinum is a Gram- positive rod. It is a spore-former and an
obligate anaerobe. It is ubiquitous, so is widely distributed in soil and marine
sediments throughout the world. It is also found in the intestinal tract of
animals, including fish.
Non-proteolytic strains of Clostridium botulinum are psychrotrophic. It is
because of their non-proteolytic characteristics, that their growth in foods
cannot be detected by off-odours and off-flavours.
The risk of toxin production
prior to the food becoming unacceptable to the consumer is considerably
higher than in those foods contaminated with proteolytic strains. In the spore
form, it is resistant to heat treatments such as pasteurization. A heat process
called a “Botulinum Cook” at high temperatures is commonly recommended
for low acid canned products. 
Clostridium botulinum produces preformed toxins. The toxin itself can be
destroyed by heat treatment (80°C or above) for only a few seconds. Botulism
is extremely serious and unless recognized and treated promptly, carries a high
risk of mortality. It is the most severe form of food poisoning.
Most of the outbreaks of botulism have been associated with products of fish
or marine animals, meat and fruit and vegetables – including mushrooms.
Insufficiently heated, canned and bottled foods are at high risk as these provide
the anaerobic environment required by the organism to grow. 
inadequately processed products such as farm-cured pork products or those
produced where process control is insufficient e.g. traditional fermented
products have also been implicated in outbreaks.


Salmonella is a Gram-negative motile rod. It is non-spore forming and
facultatively anaerobic in nature. Pasteurization and equivalent heat treatments
will generally destroy the organism.
The main source of Salmonella for man is food from infected food animals.
These animals become infected via the environment, contaminated feed or
water, or from other infected animals, birds or rodents. Therefore, meat,
poultry, raw milk and eggs should be considered as potentially contaminated
with Salmonella.
Types of foods involved in food borne salmonellosis have been wide -ranging,
but involve mainly poultry and meat products, egg and egg products, cereal
and grain products, desiccated coconut, chocolate and dairy products.
The clinical disease of Salmonella infection is gastroenteritis. It is one of the
main causes of food borne illness the world over. Although death from
salmonellosis is rare, it can occur in “at risk” groups, e.g. infants, the elderly
and the immuno -compromised (such as hospital patients).

Listeria monocytogenes

Listeria monocytogenes is a Gram -positive, non-sporing rod. It is aerobic and
facultatively anaerobic in nature. Listeria monocytogenes is psychrotrophic in nature Of all the non-sporing, vegetative food pathogens, Listeria is the most
heat resistant. It is, however, generally agreed that milk pasteurization will
destroy normal levels of L. monocytogenes in milk.
Listeria is ubiquitous in the environment and so can be transferred to foods
from a wide variety of sources. Infection from Listeria can also originate from
direct or indirect contact with animals (sheep and cows can both excrete L.
monocytogenes in faeces and sometimes in milk).
Listeriosis is a comparatively rare disease; however, because of the potential
severity of the disease, measures for its control in foods are very important. 
is generally agreed that the majority of cases of listeriosis are food borne and
may be preventable. Symptoms are typically meningitis or septicaemia and in
pregnant women it can cause a flu-like illness, which can result in miscarriage,
stillbirth or birth of a severely ill infant.

Staphylococcus aureus

Staphylococcus aureus is a Gram-positive coccus. It is a non-motile, nonsporing, facultative anaerobe. Staphylococcus aureus can grow within the
temperature range 7°C – 48°C, with an optimum of 35°C – 37°C.

Although Staphylococcus aureus is a ubiquitous organism, the largest reservoir
of enterotoxin producing staphylococci is man. Therefore, the presence of
staphylococci in cooked or processed foods can serve to indicate poor hygiene
amongst food handlers. 
Animals may also act as a source of Staphylococcus
aureus. Typically raw milk and raw meat (particularly pork) may be
contaminated with the organism. Some strains of Staphylococcus aureus are
capable of producing heat-stable toxins (enterotoxins) in food. 
It is the toxin
that causes the typical symptoms associated with Staphylococcus aureus food
poisoning. Typical symptoms are nausea and vomiting with occasional
abdominal cramping and diarrhoea. Foods involved in Staphylococcus aureus
food poisoning are typically those that have been handled and then temperature
abused prior to consumption. 
Foods implicated in Staphylococcus aureus food
poisoning have been cooked meats (notably salted meat such as ham), poultry
products, custard or cream -filled pastries, egg foods, cheese, prawns and
salads containing potato.

Shigella spp

The genus Shigella consists of four species: S. dysenteriae (subgroup A), S.
flexneri (subgroup B), S. boydii (subgroup C), and S. sonnei (subgroup D). –
sporulating, non -motile rods in the family Enterobacteriaceae.
Shigellosis, although commonly regarded as waterborne, is also a food borne
disease restricted primarily to higher primates, including humans. Food
handlers with poor personal hygiene usually spread it among humans. Foods
most often incriminated in the transmission have been potato salad, shellfish,
raw vegetables, and Mexican dishes.

Vibrio cholerae

The genus Vibrio includes Gram-negative, oxidase-positive (except two
species), rod- or curved rod-shaped facultative anaerobes. Many Vibrio spp.
are pathogenic to humans and have been implicated in food borne disease.
Pathogenic V. cholerae produces a heat-sensitive enterotoxin that causes the
characteristic cholera symptoms, including “rice water stool.”

Water and Food Associated Viruses

Several viruses like Hepatitis A, Norwalk and Norwalk like viruses; Poliovirus
and Echovirus may cause food borne disease. Some of the other viruses that
have also been associated with food are: Astrovirus, Calcivius, Enteric
Adenovirus, Parvovirus and Rotavirus. 
These enteric viruses replicate in the
intestine of infected individuals and are transmitted by faecal-oral route. The
most common types of food-borne viral diseases are Hepatitis A (infectious
hepatitis) and acute viral gastroenteritis.
The Hepatitis A virus (HAV) is one of more than 70 members of enterovirus
group of Picronaviridae family. Food borne viral gastroenteritis is usually a
mild disease with various degrees of nausea, diarrhoea, malaise, abdominal
pain, muscle pain, anorexia, headache, and low-grade fever. Illness develops
20 to 50 hours after the consumption of contaminated food and lasts for 1 to 8
Ice, water, ice cream, milk, pastries, salads, sandwiches, shellfish, and other
foods consumed raw or subjected to additional handling after cooking are
major food vehicles for virus transmission.

Preventive Measures

Prevention and control of food borne disease depends on careful food
production, handling of raw products and preparation of finished products.
Hazards can be introduced at any point from field to table. 
The 20th century
witnessed revolution in food sanitation and hygiene including refrigeration,
chlorination of drinking water, pasteurization of milk, potassium permanganate
washing of root vegetables like carrots, lettuce etc. which was a consequence
of applied technologies.
Chlorination of drinking water sources for food animals, sanitary slaughter and
processing of meat, poultry and seafood, irradiation and other microbial
reduction measures for raw agricultural commodities are significant as
approaches for food safety. 
Hazard Analysis Critical Control Point (HACCP)
process occurs when monitoring and control technologies are systematically
applied to food production to prevent food borne illnesses.
Food cooks are the last but one point of critical control before meal is
consumed, the last being those responsible for meal service on the table or in
the dishes. Therefore, interventions to promote safe food practices are needed.

Leave a Comment