How long does food poisoning last?

The term ‘food poisoning’ can be misleading. It really does not have to do with conventional poison, intentional injury and death as often believed. Food poisoning is simply an infection or irritation of the digestive tract that spreads through foods or drinks. It occurs when an individual eats food contaminated with microorganisms which can cause symptoms.  There are many germs that can contaminate foods, subsequently, there are many different foodborne types of food poisoning. The CDC estimates that each year 48 million people get sick from food poisoning, 128,000 are hospitalized, and 3,000 die.

According to the WHO, an estimated 600 million, which is almost 1 in 10 people in the world fall ill after eating contaminated food and 420 000 die every year, resulting in the loss of 33 million healthy life years (DALYs). About US$110 billion is lost each year in productivity and medical expenses resulting from unsafe food in low- and middle-income countries, and Children under 5 years of age carry 40% of the food poisoning cases, with 125 000 deaths every year.

What are the causes of food poisoning?

Researchers have identified more than 250 foodborne diseases. Most of them are infections, caused by a variety of bacteria, viruses, and parasites. Harmful toxins and chemicals also can contaminate foods and cause foodborne food poisoning.

The commonest bacteria that cause food poisoning are Salmonella, Campylobacter, and Enterohaemorrhagic Escherichia coli. These affect millions of people annually.

Examples of foods involved in outbreaks of salmonella food poisoning are eggs, poultry and other products of animal origin. Cases with Campylobacter are mainly caused by ingestion of raw milk, raw or undercooked poultry and drinking water. Enterohaemorrhagic Escherichia coli is associated with unpasteurized milk, undercooked meat and fresh fruits and vegetables Other significant bacteria that cause food poisoning are: Vibrio cholera, Staphylococcus aureus, and Clostridium perfringens .

Viruses that cause food poisoning include Norovirus and Hepatitis A virus, and infected food handlers mostly transmit this.

Parasites like fish –borne trematodes, tapeworms, round worms, and Entamoeba histolytica cause food poisoning when they contaminated ingested food, especially if poorly cooked.

Harmful chemicals when ingested can also cause food poisoning.

What are the risk factors of food poisoning?

Any type of food can cause food poisoning; however, some conditions make

food poisoning more likely. These risk factors are:

Food that is not washed thoroughly

Food that is not cooked or reheated thoroughly

Food that is not stored correctly for example, it has not been frozen or chilled

Food that is left out for too long

Food that is handled by someone who is ill or has not washed their hands and

Food that is eaten after its “use by” date.

What are the symptoms of food poisoning?

Symptoms of food poisoning range from mild to severe and vary depending on the type of organism causing the contamination. Symptoms may appear 1 to 6 hours after eating contaminated food, or they may take days or weeks to develop. They are:

Diarrhea. This is the commonest symptoms of food poisoning. Others are: Stomach cramps, Nausea and vomiting, Loss of appetite, Fever, Chills, and Weakness.

In severe cases, signs and symptoms may include dehydration, blood in vomit or stools, diarrhea over three days, and neurologic symptoms like weakness, blurry vision, and an abnormal sensation of the body such as burning, tingling, or numbness (paresthesias).

How long does food poisoning last?

The duration of symptoms of food poisoning depend on the type of organism, the age and immunity of the affected person. It is worse and lasts longer in children and the elderly or Geriatric population.

Sickness caused by food poisoning is usually not very serious or life threatening and mostly resolves on its own without specific treatment. It generally lasts from a few hours after exposure to several days.

For bacteria the sickness can last from 24 hours to 7 days. Symptoms of parasitic food poisoning, like giardia, can last 2-6 weeks.

Viruses, especially Norovirus generally lasts from 1-3 days. Hepatitis A, however, can last up to 6 months, but people generally only present symptoms for a few weeks.  

Depending on the nature of chemical contaminant of the food, food poisoning due to chemicals can be very fatal and can last from hours to days.

Treatment of food poisoning

Most people do not need medical help for food poisoning, as their symptoms are not severe and will not last long. The main home treatment is to stay hydrated by drinking water, sucking on ice chips, replacing lost fluids and electrolytes with over-the-counter oral rehydration solutions, and easing back into normal diet and routine when symptoms subside. Antibiotics may help with some bacterial types of food poisoning, but are usually not needed.

However, people in high-risk groups (such as babies and elderly people) should see a doctor early on, to make sure they do not get dehydrated, especially if they cannot drink fluids due to excessive vomiting or are getting weak.

Generally, adults should see the doctor if: symptoms are severe and persist after 3 days; they still cannot keep any fluids down, more than 24 hours after getting sick, and there is blood or mucus in the vomit or diarrhea.