This is of two types:1. Toxin Type (from staphylococcus,
streptococcus and botulinism).
Infection Type (salmonella group of
Food poisoning due to bacterial toxins is most
commonly caused by the exotoxins produced by the
staph. Phyogenes, which in the great majority of
instances, is transferred by a food handler who has a
septic lesion of the hands or who is a carrier of the
organisms in his nose or throat.
The exotoxin is very resistant to heat and is not
destroyed by cooking. The toxin type of food poisoning
is less common due to hemolytic and nonhaemolytic
streptococci and very rarely due to anaerobic spore
formatting organism , with minimal gastrointestinal
disturbance. Symptoms appear in 1-3 days. Usually after
taking infected sausages; tinned fish etc.
The organisms mainly responsible belong to the
salmonella group which has its natural reservoir in
certain birds, mammals and reptiles. Salmonella
typhimurium has been found to be the organism causing
majority of the cases of this type of food poisoning. Food
may be contaminated with infected excreta of mice or
rats etc., or infection may be transferred by flies or by
human carriers employed in handling of food. The
possibility that the infection is due to a virus should be
After bacterial contamination of the food, there is danger
of bacterial multiplication at a warm temperature, as in a
kitchen for many hours or even days. This type of food
which is likely to be infected are twice cooked meat
dishes, stews, gravie soups, custards, milk, cream, also
tinned food though usually initially sterile may become
infected, if not immediately consumed after the tin has
Duck’s eggs are quite commonly infected because the
duck is a carrier of Salmonella organisms in its oviduct
and alimentary tract. While hen’s eggs are rarely
infected. Hence duck’s eggs are not suitable for
preparation of lightly cooked foods such as
custards, milk puddings etc., because boiling for 10-15
minutes is necessary if sterilization is to be secured.
Outbreaks of food poisoning are liable to occur when
large amounts of food are prepared and when the
remaining food is not consumed is kept for future meals.
The danger of infection is greatly increased if such food
is kept in a warm temperature instead of being stored in
a refrigerator. Food poisoning is reported frequently
from canteens, restaurants, and other institutions than
from private houses .
In food poisoning; it is common to find other members of
the household or institution affected simultaneously. The
incubation period of different types is a useful pointer to
their etiology. If vomiting starts after taking a poisonous
food: Within half hour, is likely to be a chemical poison.
Within six hours, it is probably bacterial toxins.
12 to 48 hours later, it is probably due to salmonella
infection. There is toxaemia and gastroenteritis
resulting from bacterial infection.
The symptoms in any single outbreak vary widely in
severity depending on the type and the amount of
poisonous substance ingested and the susceptibility
(particularly in salmonella) of individuals. The principal
symptoms are nausea, vomiting, diarrhea and abdominal
pain. Sometimes chill and headache are initial symptoms
in salmonella food poisoning. In severe cases there may
be prostration, collapse and signs of dehydration.
In chemical and toxin type of food poisoning, the onset
tends to be sudden and severe and the patient rapidly
passes into a state of collapse and frequently has
subnormal temperature. Recovery however usually
occurs within 24 hours after treatment.
In the infection type of food poisoning (due to
salmonella), symptoms develop more slowly and there
may be a rise in temperature. The patient may be ill for
several days. The stools are watery and offensive, and
there may be little blood and some mucus, in contrast to
bacillary dysentery where there is in addition much pus.
This type is differentiated from staphylococcal
enterotoxin by three characteristics:
1. Muscular weakness
Very foul smelling diarrhea.
The most important point to decide, especially in
children is whether a surgical condition (As.
Appendicitis, intestinal obstruction etc.) is present
Collect patient’s faeces, vomit and suspected food and
send to the pathological laboratory and the chemical
examiner (for chemical poison) Isolation of bacteria
(salmonella group) by culture and agglutination test, if
positive Health Officer be informed. After death isolate
bacteria from bowel.
Most cases are mild and can be treated with rest in
bed, warmth and plenty of fluid drinks. Moderately or
severely ill showing signs of collapse and dehydration
should be admitted in hospital for proper treatment and
nursing; treat by:
Wash out stomach
Give saline purgative if necessary
I.V. dextrose saline
Stimulants if necessary
Stop food by mouth until the acute symptoms are over
and give fluids fruit juices, tea etc. On improvement
semisolid food is taken
For diarrhea give Kaolin 15g doses two hourly suspended
Antibiotic – Chloromphenical 2 g daily for about 5 to 7
Antitoxic (anti-botulinus) serum in Botulism.
• Coordinate with public health during initial threat
assessment and investigation
• Contact and coordinate with Bureau of Investigation
• Conduct criminal investigation.
• Ensure collection of evidence in manner that is
admissible in court.
Investigators in both law enforcement and
environment will also have to work together to
the answers to the following questions:
• How would perpetrators gain access to food?
• How could a pathogen be introduced?
• How was the agent mixed or distributed?
• How might the pathogen spread in the
The main objectives of laboratory analysis during
outbreak investigations are (1) to confirm the
clinical diagnosis through identification of the
causative agent from human specimens, (2) to
ensure proper identification of the disease, and (3)
to determine if the causative agent is present
in the implicated environmental source, such as
collection of clinical specimens as early in the course
investigation as possible. Most foodborne infections
are diagnosed through the identification of
the pathogen in stool collected from infected persons.
Vomitus has also been used to detect
certain organisms and confirm the etiology. Serology
and blood cultures are recommended for
the laboratory diagnosis of systemic infections.
Proper collection of stool specimens requires having
stool kits readily available, using the
appropriate kit for the suspected disease, and
encouraging ill persons to submit a stool specimen.