Food Poisoning

food poisoning symptoms

Posted on: 26/09/2018

Overview of food poisoning

Global mortality rates are exponentially increasing every year due to lack of minimum hygiene conditions in the low and middle-income countries. World Health Organization (WHO) has reported that 3,51,000 death cases worldwide are documented each year due to “Food-borne diseases”. Foodborne diseases are the leading causes of epidemics in the underdeveloped countries. Hence global health organizations are stressing the need for mandatory food inspection in every country and enforcement of strict legal actions in case of any deviation from accepted standards of food quality.


What is food poisoning?


Food poisoning refers to the chain of diseases that follow after consumption of contaminated food items or fluids.

It is characterized by severe digestive disorders which can even prove to be fatal if allowed to persist.

Food poisoning incidences all over the world are mainly caused by bacterial infections.

Hence the number of food poisoning cases is highest in tropical and subtropical countries or regions with hot and humid climate, which are ideal for growth and propagation of harmful bacteria.

It can affect people of any age group, gender or ethnicity.Food items that are prone to bacterial contamination are- milk (unpasteurized), poultry, red meat, rice, eggs and few sea-foods (like shellfish).


What causes food poisoning?

Food poisoning is catalyzed by two main bacterial species – Salmonella and Staphylococcus. Food poisoning symptoms due to Staphylococcus species are manifested within 1 to 5 hours of consumption of the enterotoxin (released by the bacteria). Causative agents of food poisoning are mainly of three categories-

  • Bacteria
  • Virus
  • Chemicals (toxins)

The generalized causes (routes) of food poisoning are discussed below-

  • Eating or cooking without washing hands
  • Preparing food in unclean vessels
  • Storing or preparing food under extreme temperature conditions (5oC-60oC)
  • Buying food items from unreliable retailers
  • Overdose of insecticides or pesticides in few food items (crops)
  • Cross-contamination due to careless handling of food materials (Eg: Mixing up raw and cooked food)
  • Eating food items (sliced fruits) kept in open air for a prolonged period (increases chances of bacterial infections)
  • Presence of excessive preservatives in frozen food items
  • Having partially cooked or uncooked food
  • Having food without checking expiry dates
  • Storing food items in rusty, unclean and corroded containers
  • Consuming food items touched by animals (mainly pets) at home
  • Cooking food with polluted water
  • Loss of body’s immune capacity to combat infection


What are the warning signs?

Symptoms of food poisoning might mimic minor digestive disorders or related ailments.

Hence if the symptoms persist for a long time, a doctor must be consulted.

The symptoms might start manifesting themselves after 2-5 days of consumption of contaminated food, but can persist till 1-11 days.

Listed below are the characteristic symptoms of food poisoning.

  • Severe stomach pain
  • Long spells of nausea and vomiting (at times with blood)
  • Diarrhoea like symptoms (frequent watery stool)
  • Blood in stool
  • Stomach cramps after repeated instances of Diarrhoea
  • Impaired functioning of kidneys (in extreme cases)
  • Fever and headache
  • Body pains (mainly lower back pains)
  • General feeling of illness
  • Dizziness and extreme fatigue
  • Complete loss of appetite
  • Lack of digestive capacity
  • Premature labour pains (pregnant women)
  • General muscle cramps
  • Mental instability
  • Seizures and convulsions after repeated instances of diarrhoea
  • Impaired functioning of nervous system
  • Blurred vision and indistinct speech (in critical cases)
  • Mild paralysis conditions in few extreme cases
  • Occasional chills
  • Loss of body balance
  • Dehydration due to abnormal loss of body fluids
  • Rapid heart rate
  • Rapid and shallow breathing


What are the different types of food poisoning?

Depending on the causative agent of contamination, food poisoning can be categorized into the following types-

Microbial food poisoning: It occurs due to contamination by microbes such as Salmonella, Clostridium, Escherichia, Staphylococcus. Toxins released by these microbes invade the body and cause food poisoning symptoms.

Chemical food poisoning: It is induced by different toxic chemicals that enter the bloodstream via different paths. It has the following subtypes-

  • Metal poisoning: It results from preserving food items (acidic ones) in metal containers (coated with cadmium, zinc or lead) or cooking in ill-maintained utensils.
  • Pesticide poisoning: It can occur if vegetables or fruits (containing excess pesticides) are cooked and consumed without washing properly.
  • Chemical toxin poisoning: It is caused by trace amounts of cleaning agents (that linger in food products) used in food manufacturing industries.
  • Preservative/additive poisoning: It occurs due to the presence of excess preservatives or additive agents (for color) in the food items.
  • Sterilizing agent poisoning: Residues of sterilizing or cleaning agents in cooking utensils can mix with food items and cause poisoning effects.
  • Natural food poisoning: It can occur due to accidental consumption of marine animals or plants that may contain toxic elements (Eg: Few poisonous varieties of mushroom)


Who are vulnerable to food poisoning?

People belonging to all age groups and ethnic groups are equally prone to food poisoning. But the following groups lack immunity to combat minor infections-

  • Aged people (due to degenerated immune systems)
  • Infants (due to underdeveloped immune systems)
  • Patients with chronic illnesses such as diabetes, high blood pressure (due to their disturbed immune systems)
  • People with naturally weak immune systems (immunocompromised people)
  • Pregnant women (due to their unstable immune system)



Doctors will be able to differentiate between general digestive disorders and disorders due to food poisoning via blood tests, stool tests, rectal examination, toxoplasmosis tests and CT scan of the abdomen. The government bodies in different countries should adopt strict policies related to food safety and hygiene to reduce the global burden of food poisoning. Underprivileged people in different countries should be educated about the consequences of food poisoning. This way, a strategic planning can be devised to alleviate the existing global health scenario.


Treatment and Precaution

The treatment protocol for food poisoning involves two important steps which include replacement of lost bodily fluids and antibiotic drugs to counter any bacterial infection. Since the patient is losing a lot of fluids and electrolytes in the form of diarrhea and vomiting, he/ she might get severely dehydrated. To prevent this, he/she must be given minerals such as sodium, potassium, and magnesium either intravenously or orally. Antibiotic drugs are only helpful if the food poisoning has occurred due to bacterial infection.

Such drugs are of no use if the infection is viral. In fact, administering antibiotics drugs for the viral infection is counterproductive to treatment. In addition to these, it is important that the patient refrains from consuming any kind of food for a few hours and only suck on ice chips.  He/she should not consume greasy, spicy, and heavy food immediately after the treatment course.

Caffeine, alcohol, milk and dairy items, nicotine, tobacco, spicy foods should be avoided at all cost. Eat non-greasy, easy to digest food such as curd and fresh fruits. Getting ample rest is critical to the treatment process.  Generally, food poisoning spreads from contaminated meat. Always make sure that the meat (or poultry) is cooked at a temperature of 70-80 deg C at least to kill the microbes.  Leftover food should be refrigerated properly. When traveling, it is best to consume packaged or boiled water. Keep your hands sanitized.  Be wary of eating raw seafood and soft cheeses.



Food poisoning infographic


  • Foodborne diseases are very common ailment affecting millions, 48 million to be precise, every year.
  • It kills 5,000 Americans every year and almost 300,000 cases are hospitalized annually.


  • Green leafy vegetables, eggs, oysters, cheeses, and tomatoes – these are the edible items that get contaminated first with food-poisoning microbes.
  • A considerable amount of food-poisoning occurrence can be controlled if people cleaned their hands more often.


  • Washing poultry/meat/seafood doesn’t help remove germs from the food. In fact, it increases the likelihood of cross-contamination.
  • Around 2-4 million cases of salmonella go undiagnosed every year.

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Dos and Don'ts

  • The refrigerator is a breeding ground for disease-causing microbes. Keep it in a clean and sterile condition and make sure the temperature is low enough to deter microbial growth.
  • Always use a meat thermometer to check whether the meat is cooked or not, especially beef. Meat always looks well-done before it is actually safe for consumption.
  • Heating pads placed on abdomen will help relieve the pain.
  • Eat food which has been kept at room temperature for more than two hours. In a buffet, food items ideally should be kept on ice or heated continuously.
  • Consume sugary foods, packaged goods, tea, or coffee.
  • Dehydrate yourself. Keep drinking healthy fluids to balance the loss of water.




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