Food Poisoning

Food Poisoning Introduction

Food poisoning is an acute gastroenteritis caused by the consumption of a food material or a drink which contains the pathogenic micro organism or their toxins or poisonous chemicals.Food poisoning is common in hostels,hotels,communal feedings, and festival seasons.

Food Poisoning

Food Poisoning

A group of persons will be affected with same type of symptoms ,and they give a history of consumption of a common food before few hours.

Food poisoning, also called food borne illness, is illness caused by eating contaminated food. Infectious organisms – including bacteria, viruses and parasites  or their toxins are the most common causes of food poisoning.

Infectious organisms or their toxins can contaminate food at any point of processing or production. Contamination can also occur at home if food is incorrectly handled or cooked.

Food poisoning symptoms, which can start within hours of eating contaminated food, often include nausea, vomiting or diarrhea. Most often, food poisoning is mild and resolves without treatment. But some people need to go to the hospital.


Contamination of food can happen at any point of production: growing, harvesting, processing, storing, shipping or preparing. Cross-contamination – the transfer of harmful organisms from one surface to another — is often the cause. This is especially troublesome for raw, ready-to-eat foods, such as salads or other produce. Because these foods aren’t cooked, harmful organisms aren’t destroyed before eating and can cause food poisoning.

Many bacterial, viral or parasitic agents cause food poisoning. The following table shows some of the possible contaminants, when you might start to feel symptoms and common ways the organism is spread.

Contaminant Onset of symptoms Foods affected and means of transmission
Campylobacter 2 to 5 days Meat and poultry. Contamination occurs during processing if animal feces contact meat surfaces. Other sources include unpasteurized milk and contaminated water.
Clostridium botulinum 12 to 72 hours Home-canned foods with low acidity, improperly canned commercial foods, smoked or salted fish, potatoes baked in aluminum foil, and other foods kept at warm temperatures for too long.
Clostridium perfringens 8 to 16 hours Meats, stews and gravies. Commonly spread when serving dishes don’t keep food hot enough or food is chilled too slowly.
Escherichia coli (E. coli) O157:H7 1 to 8 days Beef contaminated with feces during slaughter. Spread mainly by under cooked ground beef. Other sources include unpasteurized milk and apple cider, alfalfa sprouts, and contaminated water.
Giardia lamblia 1 to 2 weeks Raw, ready-to-eat produce and contaminated water. Can be spread by an infected food handler.
Hepatitis A 28 days Raw, ready-to-eat produce and shellfish from contaminated water. Can be spread by an infected food handler.
Listeria 9 to 48 hours Hot dogs, luncheon meats, unpasteurized milk and cheeses, and unwashed raw produce. Can be spread through contaminated soil and water.
Noroviruses (Norwalk-like viruses) 12 to 48 hours Raw, ready-to-eat produce and shellfish from contaminated water. Can be spread by an infected food handler.
Rotavirus 1 to 3 days Raw, ready-to-eat produce. Can be spread by an infected food handler.
Salmonella 1 to 3 days Raw or contaminated meat, poultry, milk, or egg yolks. Survives inadequate cooking. Can be spread by knives, cutting surfaces or an infected food handler.
Shigella 24 to 48 hours Seafood and raw, ready-to-eat produce. Can be spread by an infected food handler.
Staphylococcus aureus 1 to 6 hours Meats and prepared salads, cream sauces, and cream-filled pastries. Can be spread by hand contact, coughing and sneezing.
Vibrio vulnificus 1 to 7 days Raw oysters and raw or under cooked mussels, clams, and whole scallops. Can be spread through contaminated seawater.

Types of food poisoning

1) Bacterial food poisoning:

Here the micro organisms called bacteria are responsible.The food material may contain the pathogenic bacteria or their toxin and will be ingested along with the food.

2) Non bacterial food poisoning:

Due to the presence of toxic chemicals like fertilizers, insectisides, heavy metals & Ect

Since bacterial food poisoning is common it is discussed here.

Bacterial food poisoning:

All bacteria are not harmful.There are some pathogenic bacteria which secrete toxins and cause clinical manifestations.These organisms enter the human body through food articles or drinks.

How food poisoning occurs:

1) Presence of bacteria in the water.

2) The raw materials for the food may contain toxins.

3) Premises where the food is prepared may contain micro organisms or toxins.

4) Food handlers may have some infectious diseases.

5) Some animals like dogs,rats may contaminate the food.

6) If prepared food is kept in the room temperature for a long time and heated again can make a chance for food poisoning.

7) Purposely some body mixing toxins in the food.

Some common bacterial food poisonings.

1) Salmonella food poisoning:

There are three different varieties of salmonella bacteria.(salmonella typhimurium,salmonella cholera suis,salmonella enteritidis) These bacteria are present in milk, milk products and eggs.  Symptoms of this food poisoning include nausea, vomiting and diarrhoea.  Fever is also common.

2) Botulism:

This is the dangerous type of food poisoning caused by clostridium botulinum.   The spores of these organisms are seen in the soil and enters the human body through pickles and canned fish ect.Compared to other food poisonings here vomiting and diarrhoea are rare Mainly the nervous system is affected.The symptoms starts with double vision,numbness with weakness.Later there will be paralysis with cardiac and respiratory failure ending in death.

3) Staphylococcal food poisoning:

It is caused by staphylo coccus aureus. These organisms usually cause skin troubles like boils and eruptions.It causes mastitis in cow.Through the milk and milk products it enders and causes gastroenteritis.There will be vomiting,abdominal cramps with diarrhoea.

4) Closteridium food poisoning:

This is caused by closteridium perfringens. They are present in stool,soil and water. They enter the body through,meat,meat dishes and egg etc. If food articles are cooked and kept in room temperature for a long time and heated again before eating can result this food poisoning.Symptoms include vomiting, diarrhoea and abdominal cramps.

5) Bacillus cereus:

The spores of these organisms can survive cooking and causes enteritis. Diarrhoea and vomiting is common in this infection.

How to investigate food poisoning?

1) Examine each and every person affected.

2) Water sample should be tested.

3) Kitchen, store room and food samples should be examined.

4) The cook and food handlers should be questioned and examined.

5) Samples of vomits and stool of all victims should be tested to identify the bacteria.

How to prevent food poisoning:-

1) Only purified water should be used.

2) Hygiene should be maintained by all persons keeping contact with food.

3) Workers should use masks, cap and gloves during cooking and serving.