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
anaerobic rod. It is ubiquitous in nature, commonly found in soil (especially
rice, paddy, soil) and vegetation.
including cereal and cereal derivatives, spices, milk and dairy products, vanilla
sauce, recipe dishes, chicken soup, mashed potatoes, vegetables, rice dishes
and dried foods.
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.
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.
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.
because of their non-proteolytic characteristics, that their growth in foods
cannot be detected by off-odours and off-flavours.
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.
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.
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.
facultatively anaerobic in nature. Pasteurization and equivalent heat treatments
will generally destroy the organism.
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
but involve mainly poultry and meat products, egg and egg products, cereal
and grain products, desiccated coconut, chocolate and dairy products.
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).
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.
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).
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 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.
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.
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.
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.
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.
flexneri (subgroup B), S. boydii (subgroup C), and S. sonnei (subgroup D). –
sporulating, non -motile rods in the family Enterobacteriaceae.
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.
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
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.
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.
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
foods consumed raw or subjected to additional handling after cooking are
major food vehicles for virus transmission.
production, handling of raw products and preparation of finished products.
Hazards can be introduced at any point from field to table.
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.
processing of meat, poultry and seafood, irradiation and other microbial
reduction measures for raw agricultural commodities are significant as
approaches for food safety.
process occurs when monitoring and control technologies are systematically
applied to food production to prevent food borne illnesses.
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.