Food Poisoning

Food Poisoning: Causes, Signs, Symptoms And Treatment

What is Food Poisoning?

Food poisoning is a disease that is associated with drinking fluids or eating liquids or solids that are infected with specific bacteria, viruses, parasites or chemical toxins.

When is Food Contaminated?

Credit: Wellcome Library, London. Wellcome Images

Contamination of food can occur during any point of the production: growing, harvesting, processing, storage, preparation or shipping. The cause is often cross contamination which is the transfer of harmful organisms from one surface to another. As food is not cooked, harmful organisms are not destroyed prior to eating and this can lead to food poisoning in the case of raw, ready to eat foods.

Causes of Food Poisoning

Bacteria and Viruses

These are the most common cause of food poisoning. Symptom and severity of food poisoning vary depending upon whether the bacterial or virus is responsible for food contamination.


These are organisms deriving nourishment and protection from hosts/living organisms. Most common foodborne parasites include roundworms, tapeworms and protozoa.

Contaminants, Toxins and Moulds

Most food poisoning is associated with bacteria, viruses and parasites rather than toxic substances linked to the food. Some cases of food poisoning can be associated with natural toxins, others with chemical toxins.


Food poisoning can also be caused by allergens which are an abnormal response to the food triggered by the immune system of the body. Foods associated with allergies include different kinds of nuts, eggs, seafood or milk.


Food poisoning is a common and distressing life-threatening problem for people in the US and throughout the world. People infected with foodborne organisms can have no symptoms or even mild to severe poisoning resulting in death. Close to 250 different diseases are the causes of food poisoning. Some of the most common diseases are infections associated with bacteria. Common infections associated with food poisoning include the following:

Campylobacter Infection

Campylobacter is a bacterium associated with acute diarrhoea. Transmission occurs via ingestion of contaminated water, food or unpasteurized milk or contact with infected persons or wild animals. Meat and poultry are the foods affected by this bacteria within a span of 2-5 days.

Campylobacter infection is serious, especially if you have a weakened immune system. Campylobacter infection can also lead to more health problems associated with brain, nerve or reactive arthritis.



Most people recover completely in a span of some days to some months. Others may suffer from reactive arthritis which has symptoms like joint pain and eye irritation. Salmonella infection rarely causes death.

It can occur in the young, very old or those with immune systems that are weakened. This infection can develop within 1-3 days and is associated with raw or contaminated meat products, milk or egg yolks, whereby inadequate cooking is also associated with this condition.

It can be spread by knives as well as cutting services and food handlers which are infected.


This is a bacteria transmitted through faecal matter. It leads to dysentery and severe diarrhoea. The disease generally occurs in tropical or temperature climates where there is poor hygiene.

Shigella takes 24-48 hours to impact and is generally found in seafood as well as raw, ready-to-consume produce.

Giardia Lamblia

This takes 1-2 weeks to impact. It affects humans through raw, ready-to-eat produce and contaminated fluids. It can be spread by an infected food handler, but there are natural remedies for giardia.

Hepatitis A

This has a gestation period of 28 days. It includes raw, ready-to-eat produce and shellfish from water that is contaminated. Again, infected food handlers can impact the body and infect it.


This takes 9 to 48 hours to develop and can be spread through contaminated soil and water. It is generally carried in hot dogs, luncheon meats, unpasteurized milk and cheese as well as unwashed raw fruits and vegetables. Listeria infection is diagnosed through medical history and confirmed with blood or spinal fluid tests. Antibiotic treatment will cure the infection but even with prompt treatment, certain infections result in death. This infection can be fatal in seniors.


These take 12 to 48 hours to develop and comprise raw, ready-to-eat produce as well as shellfish from contaminated water. It can be spread by the infected food handler.


This takes 1-3 days and is transmitted through raw, ready to consume products. It can be spread by an infected food handler.

E.coli 0157:H7

E.coli 0157:H7 is causing foodborne illnesses. This infection is generally the result of eating undercooked, infected ground beef or consuming unpasteurized milk and swimming in or drinking sewage-contaminated water. Bacteria can also be passed from stools of infected persons.

It is also associated in severe cases with hemolytic uremic syndrome and often requires treatment in the ICU. This is also associated with kidney failures.


Bacterium Clostridium botulinum causes this rare, but serious illness. The three main types are:

  • Foodborne
  • Wound
  • Infant botulism

Foodborne botulism is caused by eating foods that contain the toxin. Would botulism is caused by a toxin produced from an infected wound while Infant botulism is associated with consumption of spores of botulinum bacteria growing in the intestine.

If symptoms are left untreated, they can lead to paralysis of arms legs trunk and respiratory muscles. Respiratory failure and paralysis may require intensive medical care. Antitoxin medication can be used to treat foodborne botulism diagnosed in early stages.

This form of food poisoning occurs 12-72 hours and home-canned foods with low acidity and improperly canned commercial foods kept placed in a warm temperature for far too long can cause botulism.

Clostridium Perfringens

This is a bacteria which takes 8-16 hours to impact the body.It is found in meats, stews and gravies that are not kept hot enough or chilled too slowly.

Staphylococcus aureus

This takes 1-6 hours to impact. Meats, prepared salads, cream sauces and cream filled pastries can contain it. This infection is spread by hand contact, coughing and sneezing.

Vibrio vulnificus

This takes 1-7 days to impact the human body. It is caused by raw oysters and raw/undercooked muscles, clams and white scallops. It can also be spread through contaminated water.


Food poisoning is caused by parasites in mostly tropical countries and can spread through contaminated food. Symptoms of food poisoning caused by parasites occur within 10 days to some weeks before symptoms of feeling unwell. Symptoms can last longer if untreated. Parasites are generally ingested with contaminated food or water. Parasites ingested include Giardia, Trichinella, Taenia sodium.


Toxins cause food poisoning and are produced by bacteria on or within food products by plants and animals which can be ingested. Numerous plants and animal can be poisonous under certain conditions as listed below:

Bacteria: Plants/Animals/

Enterotoxin: Mushroom toxins Scombroid toxins

Exotoxins: Belladonna Ciguatera toxin

Cytotoxins: Ricin Sansitoxin

Neurotoxins: Hemlock Tetrodoxin

Specific chemicals are considered toxins leading to food poisoning. Around 80,000 chemicals have been used in developed countries like the United States. Many of these enter foods and cause poisoning. An example of such chemical is mercury located in drinking water and fish such as tuna or marlin. Chemicals which can be toxic if a certain amount contaminates food and water. This includes pesticides, lead and polychlorinated biphenyls.

Signs and Symptoms of Food Poisoning

Most Common Symptoms

These are the most common symptoms and they can worsen infrequently:

  • Nausea
  • Vomiting
  • Diarrhoea
  • Cramps

When common symptoms are felt by a group of persons after eating or drinking similar foods, food poisoning may be suspected. Signs and symptoms may commence within hours after eating the contaminated food or they can occur days or weeks later. Sickness caused by food poisoning lasts from a few hours to several days

Food Poisoning Symptoms by Organism

Vibrio vulnificusfever, bleeding within skin, ulcers, vomiting, diarrhoea, abdominal pain. Can be fatal to those with liver disease and low immunity.
Vibrio parahaemolyticusWatery/bloody diarrhoea, abdominal cramps, nausea, vomiting, fever.
Staphylococcus aureusSudden onset nausea and vomiting; diarrhoea and fever
Cyclospora cayetanensis

Diarrhoea, loss of appetite, substantial weight loss, stomach cramps, nausea vomiting, fatigue
E. colitraveler’s diarrhoea, watery stool, ab cramps, vomitting 3-7 days or more. Can lead to kidney failure.
Hepatitis A fever, headache, nausea and abdominal pain, jaundice, dark urine
Listeria monocytogenesfever, muscle aches, nausea, diarrhoea. Pregnant women with this disease can develop premature birth or still birth. Seniors or immune system compromised patients can develop bacteremia or meningitis.
NorovirusWinter diarrhoea or viral gastroenteritis. Diarrhoea is most prevalent in adults while nausea, vomiting, abdominal cramping, fever and headache also result.
SalmonellaDiarrhoea, fever, abdominal cramps, vomiting for 4-7 days
ShingellaAbdominal cramps, fever and diarrhoea. Stool contains blood and mucus.
Cryptosporidium IntestinalWatery stool, stomach cramps, digestive system malfunction and slight fever
Clostridium perfringensSevere abdominal cramps, watery diarrhoea
Clostridium BotulismVomiting, blurred vision, double vision, swallowing difficulty, diarrhoea and muscle weakness. Can lead to respiratory failure and death
Campylobacter jejuniDiarrhoea, cramps, fever and vomiting/Stool with blood 2-10 days
Bacillus cereusAbdominal cramps, watery stool and nausea 24-48 hours:


Severe Symptoms Require Treatment

Food Poisoning Treatment
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In case symptoms are severe or persistent, or you can be vulnerable to serious infection, further treatment may be needed. Antiemetics may be prescribed if vomiting is severe.

Replacement of lost fluids is essential because of fluids and electrolytes much as sodium, calcium and potassium maintain balance in your body. Intravenous fluids are also administered to those in need.

ORS: Oral Rehydration and Electrolytes

Clear liquids and glucose/sodium high solutions are administered to patients. WHO recommends solution with 1-litre water containing:

  • 2.5 g: sodium bicarb
  • 3.5g: sodium chloride
  • 1.5g: potassium chloride
  • 20g: Glucose

Electrolytes like Gatorade can also be used.


Medications commonly used include:

  • Absorbents: Kaopectate
  • Antisecretory agents: Pepto Bismol
  • Antiperistaltic: Only under certain conditions
  • Diphenoxylate with atropine/Lomotil
  • Loperamide/Imodium

In the absence of dysentery, antibiotics may not be prescribed.

  • Other intravenous solutions include lactated ringer solution and isotonic sodium chloride solution as well as oral electrolyte mixtures.
  • Antibiotics: Ciprofloxacin, Norfloxacin, Trimethoprim/sulfamethoxazole, Doxycycline, Rifaximin.


Generally, home remedies work for mild cases of food poisoning. But if the case is severe, you need to visit a doctor. Don’t take it lightly as food poisoning can have deadly consequences. If your symptoms worsen, visit a doctor immediately.

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