Food pathogens and
natural toxins
Nutrition Course
Why?
Understanding is key to control and
prevention
HACCP,GMP,SOP ….
Preventive measure
Food safety
What will we discuss?
Organisms
Bacteria
Protozoa and worms
Virus
Prions
Toxins
others
Who is prone?
Usually everybody (except for immunity)
Effects are more serious in vulnerable groups
Elderly
Children
Patients
Tourists
Effects are sometimes secondary
Food infection vs,food intoxication
Intoxication,due to entero- or neurotoxin
e.g,botulism,Staphylococcus aureus
Infection,from ingestion of living harmful
micro organisms
E.g,Sighella,protozoa,salmonella,hepatitis A
Intoxi-infection e.g,Vibrio cholerae
Organisms:
Bacteria
Salmonella
Description
Rod shaped
Motile
Non-spore forming
G-
Animals,poultry and pig,
Seafood…
Salmonella
Disease
Typical spp produce fever like symptoms
Diarrhea,cramps,fever,vomit
Arthritic chronic symptoms after 3 weeks are
possible
Onset time 6-8 hours
Infective dose,As few as 15-20 cells
Salmonella
Food items
Raw meats,poultry,eggs,milk and dairy
products,
fish,shrimp,frog legs,yeast,coconut,sauces and
salad dressing,cake mixes,cream-filled desserts
and toppings,dried gelatin,peanut butter,cocoa,
and chocolate,
Clostridium botilinum
Description
Anaerobic
G+
Sporeforming
Toxin!
Spores are heat
resistant
Wide spread
Soils,water,digestive
tract
Clostridium botilinum
Disease
High mortality rate !!
Food borne botulism is due to toxin
Toxin is heat sensitive (80C for 10min)
Infective dose is very small (nanograms)
After 18 to 36 hours
Neurotoxin,Double vision,difficulty in
speaking & walking
Clostridium botilinum
Food items
Sausages,meat products,canned vegetables
and seafood products
Minimally processed (heat treatment)
Honey may contain spores
Home canned foods in U.S.
All foods pH>4.6
First application of HACCP was for low-acid
canned foods in 1973
Clostridium perfringens
Description
Anaerobic
G+
rods
Spore forming
soil,sediments,and areas
subject to human or animal
fecal pollution
Clostridium perfringens
Disease
Severe diarrhea,
Deaths due to dehydration
Usually over in 24hours
Infective dose is large >10E8
Clostridium perfringens
Food items
Meat,gravy and foods that are usually not
heated such as salads,cream
Common infection; Cafeteria bacteria
Heat treatment
Institutional feeding,
large quantities of food is prepared hours in
advance
Large quantities that have to be kept warm
for a long time should be divided in small
quantities to expose to oxygen
Staphylococcus aureus
Description
Spherical,cocci
Pairs,like grapes
G+
Can produce toxin
Humans and animals
are the primary
reservoirs
> 50% of healthy
individual nasal
passages,throats and
on the hair and skin
Staphylococcus aureus
Disease
Rapid and acute
nausea,vomiting,abdominal cramping,
Recovery generally takes two days
Death from staphylococcal food poisoning is
very rare
Staphylococcus aureus
Food items
food handlers are usually the main source of
food contamination
Usually because the food has not been kept
hot enough (>60° C) or cold enough
(<7.2° C )
Meat and meat products; poultry and egg
products; salads such as egg,tuna,chicken,
potato,and macaroni; bakery products such
as cream-filled pastries,cream pies; and milk
and dairy products
Campylobacter jejuni
Description
Motile
Slender
Motile rod
G-
microaerophilic
Campylobacter jejuni
Disease
Newly recognized and most common cause
of diarrhea in U.S.
Heat labile toxin
Infective dose,400-500 bacteria !
Fever,diarrhea and abdominal pain
Self-limiting after one week
Campylobacter jejuni
Food items
C,jejuni frequently contaminates raw chicken,
Surveys show that 20 to 100% of retail
chickens are contaminated
Raw milk (cattle,flies)
Drinking water
Proper cooking,pasteurization,chlorination
will kill most bacteria
Yersinia enterocolitica
Description
Small rod,
G-
From wounds,sputum
and feces
Yersinia enterocolitica
Disease
Yersina pestis,bubonic plague
Rare
Diarrhea,vomiting
Yersinia enterocolitica
Food times
Environment,lakes,ponds,wildlife such as
birds
Meat,oyster,milk,ice-cream
Sanitation,proper storage and sterilization
Listeria monocytogenes
Description
G+
Motile,flagella
Not sporeforming!
Listeria monocytogenes
Disease
Meningitis & vomit,nausea
Symptoms like influenza,persistent fever
Pregnant women,spontaneous abortion
Listeria monocytogenes
Food items
Resistant to drying,salt,refrigeration,rare for
non spore forming!
Can multiply at 3C
Milk,raw meat,poultry,smoked fish,raw
vegetables
Vibrio cholerae
Description
Normal flora of coastal
and brackish waters
Vibrio cholerae
Disease
Viable bacteria produces toxin in small
intestine
Infective dose is 10E6
Acute,Cramps,watery painless diarrhea,
Dehydration and loss of electrolytes
Self limiting,give ORS (and antibiotics)
Children and patients!!
Vibrio cholerae
Food items
Related to poor sanitation
Contaminated water supply
South America,Bangladesh,India
Raw seafood and vegetables
Sensitive to acids and drying
Cook foods and water
Personal and food hygiene+ feces disposal
Vibrio parahaemolyticus
Description
Water environment
Fish and shell fish
Vibrio parahaemolyticus
Disease
Diarrhea,abdominal cramps,nausea,
vomiting,headache,fever
mild or moderate and self-limiting
2-3 days
10E6 cells,Toxin
Vibrio parahaemolyticus
Food items
raw,improperly cooked,or cooked,
recontaminated fish and shellfish.
Correlation exists with warmer months of the
year,
Main cause of food infection in Japan
Bacillus cereus
Description
Facultative aerobic
G+
Spore forming
Large rods
Motile (<> anthraxis spp)
Bacillus cereus
Disease
Similar to C,perfringens
toxin
Two types,Diarrhea,vomit
Bacillus cereus
Food items
Meats,milk,vegetables,and fish,diarrheal
type food poisoning,
The vomiting-type outbreaks have generally
been associated with rice products
Shigella spp
Description
Rod shaped
G-
Non-spore forming
Non motile
water contaminated by
human waste
Shigella spp
Disease
Abdominal pain; cramps; diarrhea; fever;
vomiting; blood,pus,or mucus in stools
Onset time -- 12 to 50 hours
Infective dose,as few as 10 cells
fecal-oral route
Shigella spp
Food items
Salads (potato,tuna,shrimp,macaroni,and
chicken),raw vegetables,milk and dairy
products,and poultry,
Fecal-oral route,
Fecally contaminated water and unsanitary
handling by food handlers are the most
common causes of contamination
Enterotoxigenic Escherichia coli
Discription
4 classes
Some produce enterotoxin
O157:H7 spp
E,coli is a normal
inhabitant of the
intestines of all animals.
Enterotoxigenic Escherichia coli
Disease
Watery diarrhea,abdominal cramps,low-
grade fever,nausea and malaise
Infants,tourists in less developed countries
High doses,10E7 or 10E9
Self-limiting
Enterotoxigenic Escherichia coli
Food items
not considered a serious food borne disease
hazard in countries having high sanitary
standards and practices,
Contamination of water with human sewage
may lead to contamination of foods.
Infected food handlers may also contaminate
foods,
Dairy products & undercooked meat
not pasteurized E.g,apples juice
Organism II
Protozoa and worms
Giardia lamblia (intestinales)
Single celled animal
5 flagella motile
Ingestion of cyst (survival
mechanism of protozoa)
Diarrhea after one week
One week to one month
Children
Usually contaminated water
sources
Food infections are rare
Entamoeba histolyca
Description
Single cell protozoa
Infect humans and
animals though not all
animals excrete cysts
Entamoeba histolyca
Disease
cysts survive outside the host in water and
soils and on foods,especially high aw,
Swallowed they cause infections by excysting
in the digestive tract
No symptoms to dysentery or ulceration
Infective dose can be one cell
Entamoeba histolyca
Food items
fecal contamination of drinking water and
foods,but also by direct contact with dirty
hands or objects as well as by sexual contact.
Tropics,but also in crowded situations of
poor hygiene in temperate-zone urban
environments
Organism III
Virusses
Hepatitis A and E
description
Enterovirus
Illness characterized by sudden onset
of fever,malaise,nausea,anorexia,
and abdominal discomfort,followed in
several days by jaundice
30 days mean
vaccination
Hepatitis A and E
Feces of infected people and can produce
clinical disease when susceptible individuals
consume contaminated water or foods.
Cold cuts and sandwiches,fruits and fruit
juices,milk and milk products,vegetables,
salads,shellfish,and iced drinks are
commonly implicated in outbreaks,
Water,shellfish,and salads are the most
frequent sources,
Hepatitis A and E
HAV is primarily transmitted by person-to-person
contact through fecal contamination,but common-
source epidemics from contaminated food and water
also occur,
Poor sanitation and crowding facilitate transmission,
Outbreaks of HA are common in institutions,crowded
house projects,and prisons and in military forces in
adverse situations,
In developing countries,the incidence of disease in
adults is relatively low because of exposure to the
virus in childhood.
Rotavirus
acute gastroenteritis self-limiting,
Mild to severe disease
characterized by vomiting,watery
diarrhea,and low-grade fever,
Infected person often excretes large
numbers of virus,transmission
through acquired through
contaminated hands,objects,or
utensils
It is worldwide endemic and the
leading cause of severe diarrhea
among infants and children,CHINA
Organism V
Toxins
Shellfish-Associated Toxins
caused by a group of toxins elaborated by
planktonic algae upon which the shellfish
feed.
Different types,different symptoms
neurological (e.g,respiratory paralysis) to
diarrhea
All shellfish (filter-feeding mollusks) are
potentially toxic,
Generally associated with mussels,clams,
cockles,and scallops
Aflatoxin
Aspergillus flavus fungi
Temp and RH,fungi
produces toxin
Drought + damage during
harvesting and
subsequent humidity and
high temperature
Storage conditions
Aflatoxin
Disease
Aflatoxins produce acute necrosis,cirrhosis,
and carcinoma of the liver in a number of
animal species;
No animal species is resistant to the acute
toxic effects of aflatoxins
Aflatoxin
Food items
Tree nuts,peanuts,and other oilseeds,
including corn and cottonseed
Other grains and nuts are susceptible but
less prone to contamination.
Organism IV
Prions
Prions what?
Prions are not cellular organisms or viruses
but regular components of neurological
tissues in animals
In their normal noninfectious state,these
proteins may be involved in cell-to-cell
communication,
When these proteins become abnormally
shaped i.e.,prions,they are able to transform
molecules of the normally shaped protein with
which they come into contact to the abnormal
prion configuration
Prions,disease
When consumed in the diet,prions are
thought to be absorbed into the body where,
again,they begin the process of changing
their normal protein counterparts into prions
Mad cows >> Creutzfeld Jacob disease,
neurological
Depression >>> muscle problems >> death
Prions,Food items
The major concern for consumers is the
potential contamination of meat products by
central nervous system tissue (brain and
spinal cord) during routine slaughter.
Gelatin,derived from the hides and bones of
cattle,appears to be very low risk
Others
Heavy metals (Pb,Cd),pesticides,dioxins,
antibiotics,allergies (e.g,MSG),solanine
Conclusion
Factors affecting growth
Aw,pH,Temp,Eh,composition,other flora..
Interplay of various factors is important!!
M.O,don’t need to multiply to produce toxin
Every condition must be examined separately
Careful with predictions >>> only through
experiments !!
Food most frequently involved in out breaks
of food borne diseases are from animal origin
Surveillance
Key centers for data,outbreaks etc..
natural toxins
Nutrition Course
Why?
Understanding is key to control and
prevention
HACCP,GMP,SOP ….
Preventive measure
Food safety
What will we discuss?
Organisms
Bacteria
Protozoa and worms
Virus
Prions
Toxins
others
Who is prone?
Usually everybody (except for immunity)
Effects are more serious in vulnerable groups
Elderly
Children
Patients
Tourists
Effects are sometimes secondary
Food infection vs,food intoxication
Intoxication,due to entero- or neurotoxin
e.g,botulism,Staphylococcus aureus
Infection,from ingestion of living harmful
micro organisms
E.g,Sighella,protozoa,salmonella,hepatitis A
Intoxi-infection e.g,Vibrio cholerae
Organisms:
Bacteria
Salmonella
Description
Rod shaped
Motile
Non-spore forming
G-
Animals,poultry and pig,
Seafood…
Salmonella
Disease
Typical spp produce fever like symptoms
Diarrhea,cramps,fever,vomit
Arthritic chronic symptoms after 3 weeks are
possible
Onset time 6-8 hours
Infective dose,As few as 15-20 cells
Salmonella
Food items
Raw meats,poultry,eggs,milk and dairy
products,
fish,shrimp,frog legs,yeast,coconut,sauces and
salad dressing,cake mixes,cream-filled desserts
and toppings,dried gelatin,peanut butter,cocoa,
and chocolate,
Clostridium botilinum
Description
Anaerobic
G+
Sporeforming
Toxin!
Spores are heat
resistant
Wide spread
Soils,water,digestive
tract
Clostridium botilinum
Disease
High mortality rate !!
Food borne botulism is due to toxin
Toxin is heat sensitive (80C for 10min)
Infective dose is very small (nanograms)
After 18 to 36 hours
Neurotoxin,Double vision,difficulty in
speaking & walking
Clostridium botilinum
Food items
Sausages,meat products,canned vegetables
and seafood products
Minimally processed (heat treatment)
Honey may contain spores
Home canned foods in U.S.
All foods pH>4.6
First application of HACCP was for low-acid
canned foods in 1973
Clostridium perfringens
Description
Anaerobic
G+
rods
Spore forming
soil,sediments,and areas
subject to human or animal
fecal pollution
Clostridium perfringens
Disease
Severe diarrhea,
Deaths due to dehydration
Usually over in 24hours
Infective dose is large >10E8
Clostridium perfringens
Food items
Meat,gravy and foods that are usually not
heated such as salads,cream
Common infection; Cafeteria bacteria
Heat treatment
Institutional feeding,
large quantities of food is prepared hours in
advance
Large quantities that have to be kept warm
for a long time should be divided in small
quantities to expose to oxygen
Staphylococcus aureus
Description
Spherical,cocci
Pairs,like grapes
G+
Can produce toxin
Humans and animals
are the primary
reservoirs
> 50% of healthy
individual nasal
passages,throats and
on the hair and skin
Staphylococcus aureus
Disease
Rapid and acute
nausea,vomiting,abdominal cramping,
Recovery generally takes two days
Death from staphylococcal food poisoning is
very rare
Staphylococcus aureus
Food items
food handlers are usually the main source of
food contamination
Usually because the food has not been kept
hot enough (>60° C) or cold enough
(<7.2° C )
Meat and meat products; poultry and egg
products; salads such as egg,tuna,chicken,
potato,and macaroni; bakery products such
as cream-filled pastries,cream pies; and milk
and dairy products
Campylobacter jejuni
Description
Motile
Slender
Motile rod
G-
microaerophilic
Campylobacter jejuni
Disease
Newly recognized and most common cause
of diarrhea in U.S.
Heat labile toxin
Infective dose,400-500 bacteria !
Fever,diarrhea and abdominal pain
Self-limiting after one week
Campylobacter jejuni
Food items
C,jejuni frequently contaminates raw chicken,
Surveys show that 20 to 100% of retail
chickens are contaminated
Raw milk (cattle,flies)
Drinking water
Proper cooking,pasteurization,chlorination
will kill most bacteria
Yersinia enterocolitica
Description
Small rod,
G-
From wounds,sputum
and feces
Yersinia enterocolitica
Disease
Yersina pestis,bubonic plague
Rare
Diarrhea,vomiting
Yersinia enterocolitica
Food times
Environment,lakes,ponds,wildlife such as
birds
Meat,oyster,milk,ice-cream
Sanitation,proper storage and sterilization
Listeria monocytogenes
Description
G+
Motile,flagella
Not sporeforming!
Listeria monocytogenes
Disease
Meningitis & vomit,nausea
Symptoms like influenza,persistent fever
Pregnant women,spontaneous abortion
Listeria monocytogenes
Food items
Resistant to drying,salt,refrigeration,rare for
non spore forming!
Can multiply at 3C
Milk,raw meat,poultry,smoked fish,raw
vegetables
Vibrio cholerae
Description
Normal flora of coastal
and brackish waters
Vibrio cholerae
Disease
Viable bacteria produces toxin in small
intestine
Infective dose is 10E6
Acute,Cramps,watery painless diarrhea,
Dehydration and loss of electrolytes
Self limiting,give ORS (and antibiotics)
Children and patients!!
Vibrio cholerae
Food items
Related to poor sanitation
Contaminated water supply
South America,Bangladesh,India
Raw seafood and vegetables
Sensitive to acids and drying
Cook foods and water
Personal and food hygiene+ feces disposal
Vibrio parahaemolyticus
Description
Water environment
Fish and shell fish
Vibrio parahaemolyticus
Disease
Diarrhea,abdominal cramps,nausea,
vomiting,headache,fever
mild or moderate and self-limiting
2-3 days
10E6 cells,Toxin
Vibrio parahaemolyticus
Food items
raw,improperly cooked,or cooked,
recontaminated fish and shellfish.
Correlation exists with warmer months of the
year,
Main cause of food infection in Japan
Bacillus cereus
Description
Facultative aerobic
G+
Spore forming
Large rods
Motile (<> anthraxis spp)
Bacillus cereus
Disease
Similar to C,perfringens
toxin
Two types,Diarrhea,vomit
Bacillus cereus
Food items
Meats,milk,vegetables,and fish,diarrheal
type food poisoning,
The vomiting-type outbreaks have generally
been associated with rice products
Shigella spp
Description
Rod shaped
G-
Non-spore forming
Non motile
water contaminated by
human waste
Shigella spp
Disease
Abdominal pain; cramps; diarrhea; fever;
vomiting; blood,pus,or mucus in stools
Onset time -- 12 to 50 hours
Infective dose,as few as 10 cells
fecal-oral route
Shigella spp
Food items
Salads (potato,tuna,shrimp,macaroni,and
chicken),raw vegetables,milk and dairy
products,and poultry,
Fecal-oral route,
Fecally contaminated water and unsanitary
handling by food handlers are the most
common causes of contamination
Enterotoxigenic Escherichia coli
Discription
4 classes
Some produce enterotoxin
O157:H7 spp
E,coli is a normal
inhabitant of the
intestines of all animals.
Enterotoxigenic Escherichia coli
Disease
Watery diarrhea,abdominal cramps,low-
grade fever,nausea and malaise
Infants,tourists in less developed countries
High doses,10E7 or 10E9
Self-limiting
Enterotoxigenic Escherichia coli
Food items
not considered a serious food borne disease
hazard in countries having high sanitary
standards and practices,
Contamination of water with human sewage
may lead to contamination of foods.
Infected food handlers may also contaminate
foods,
Dairy products & undercooked meat
not pasteurized E.g,apples juice
Organism II
Protozoa and worms
Giardia lamblia (intestinales)
Single celled animal
5 flagella motile
Ingestion of cyst (survival
mechanism of protozoa)
Diarrhea after one week
One week to one month
Children
Usually contaminated water
sources
Food infections are rare
Entamoeba histolyca
Description
Single cell protozoa
Infect humans and
animals though not all
animals excrete cysts
Entamoeba histolyca
Disease
cysts survive outside the host in water and
soils and on foods,especially high aw,
Swallowed they cause infections by excysting
in the digestive tract
No symptoms to dysentery or ulceration
Infective dose can be one cell
Entamoeba histolyca
Food items
fecal contamination of drinking water and
foods,but also by direct contact with dirty
hands or objects as well as by sexual contact.
Tropics,but also in crowded situations of
poor hygiene in temperate-zone urban
environments
Organism III
Virusses
Hepatitis A and E
description
Enterovirus
Illness characterized by sudden onset
of fever,malaise,nausea,anorexia,
and abdominal discomfort,followed in
several days by jaundice
30 days mean
vaccination
Hepatitis A and E
Feces of infected people and can produce
clinical disease when susceptible individuals
consume contaminated water or foods.
Cold cuts and sandwiches,fruits and fruit
juices,milk and milk products,vegetables,
salads,shellfish,and iced drinks are
commonly implicated in outbreaks,
Water,shellfish,and salads are the most
frequent sources,
Hepatitis A and E
HAV is primarily transmitted by person-to-person
contact through fecal contamination,but common-
source epidemics from contaminated food and water
also occur,
Poor sanitation and crowding facilitate transmission,
Outbreaks of HA are common in institutions,crowded
house projects,and prisons and in military forces in
adverse situations,
In developing countries,the incidence of disease in
adults is relatively low because of exposure to the
virus in childhood.
Rotavirus
acute gastroenteritis self-limiting,
Mild to severe disease
characterized by vomiting,watery
diarrhea,and low-grade fever,
Infected person often excretes large
numbers of virus,transmission
through acquired through
contaminated hands,objects,or
utensils
It is worldwide endemic and the
leading cause of severe diarrhea
among infants and children,CHINA
Organism V
Toxins
Shellfish-Associated Toxins
caused by a group of toxins elaborated by
planktonic algae upon which the shellfish
feed.
Different types,different symptoms
neurological (e.g,respiratory paralysis) to
diarrhea
All shellfish (filter-feeding mollusks) are
potentially toxic,
Generally associated with mussels,clams,
cockles,and scallops
Aflatoxin
Aspergillus flavus fungi
Temp and RH,fungi
produces toxin
Drought + damage during
harvesting and
subsequent humidity and
high temperature
Storage conditions
Aflatoxin
Disease
Aflatoxins produce acute necrosis,cirrhosis,
and carcinoma of the liver in a number of
animal species;
No animal species is resistant to the acute
toxic effects of aflatoxins
Aflatoxin
Food items
Tree nuts,peanuts,and other oilseeds,
including corn and cottonseed
Other grains and nuts are susceptible but
less prone to contamination.
Organism IV
Prions
Prions what?
Prions are not cellular organisms or viruses
but regular components of neurological
tissues in animals
In their normal noninfectious state,these
proteins may be involved in cell-to-cell
communication,
When these proteins become abnormally
shaped i.e.,prions,they are able to transform
molecules of the normally shaped protein with
which they come into contact to the abnormal
prion configuration
Prions,disease
When consumed in the diet,prions are
thought to be absorbed into the body where,
again,they begin the process of changing
their normal protein counterparts into prions
Mad cows >> Creutzfeld Jacob disease,
neurological
Depression >>> muscle problems >> death
Prions,Food items
The major concern for consumers is the
potential contamination of meat products by
central nervous system tissue (brain and
spinal cord) during routine slaughter.
Gelatin,derived from the hides and bones of
cattle,appears to be very low risk
Others
Heavy metals (Pb,Cd),pesticides,dioxins,
antibiotics,allergies (e.g,MSG),solanine
Conclusion
Factors affecting growth
Aw,pH,Temp,Eh,composition,other flora..
Interplay of various factors is important!!
M.O,don’t need to multiply to produce toxin
Every condition must be examined separately
Careful with predictions >>> only through
experiments !!
Food most frequently involved in out breaks
of food borne diseases are from animal origin
Surveillance
Key centers for data,outbreaks etc..
