Food poisoning isn’t always caused by spoiled food. Learn how bacteria, viruses, parasites, toxins and unsafe water cause foodborne diseases and how to recognize the warning signs.

WORLD FOOD SAFETY DAY: SPECIAL REPORT (PART 2)

 

In Part One of this series, we examined the tragic stories of a father of four in Ondo State and an elderly woman in Ogun State whose lives were cut short after consuming substances believed to have caused severe foodborne illness.

Their stories raise an important question:

What exactly turns an ordinary meal, drink, or herbal preparation into a potential health hazard?

The answer is often hidden from sight.

A meal may look fresh, smell normal, and taste perfectly fine while harbouring harmful bacteria, viruses, parasites, toxins, or chemicals capable of causing serious illness.

That is why health experts often describe foodborne diseases as a silent threat. The enemy is often invisible.

More Than a Stomach Upset

Many people dismiss food poisoning as nothing more than a temporary stomach problem.

However, medical experts warn that foodborne illnesses can range from mild discomfort to severe dehydration, organ failure, neurological complications, long-term disability, and death.

According to the World Health Organization (WHO), an estimated 1.52 million people die from foodborne diseases globally.

Foodborne illnesses contribute to lost productivity, increased healthcare costs, and economic hardship for families and communities.

The Bacteria Hiding in Everyday Foods

Bacteria are among the most common causes of food poisoning worldwide.

They can contaminate food at any stage—from farms and markets to kitchens and dining tables.

• Salmonella

One of the most well-known foodborne bacteria is Salmonella.

It is commonly found in raw or undercooked poultry, eggs, meat, and unpasteurized milk.

People infected with Salmonella may experience diarrhoea, fever, stomach cramps, nausea, and vomiting.

For healthy adults, recovery may take a few days.

For children, older adults, and people with weakened immune systems, the infection can become severe and even life-threatening.

• Escherichia coli (E. coli)

Certain strains of E. coli can cause serious food poisoning.

The bacteria are often linked to contaminated vegetables, undercooked meat, untreated water, and poor hygiene practices.

Symptoms may include severe diarrhoea, abdominal pain, vomiting, and, in some cases, kidney complications.

•  Listeria

For pregnant women, Listeria poses a particularly dangerous threat.

The bacterium can contaminate dairy products and ready-to-eat foods.

Infections have been associated with miscarriages, stillbirths, premature births, and severe illness in newborn babies.

•  Campylobacter and Shigella

These bacteria are commonly associated with contaminated meat, raw milk, unsafe water, and poor sanitation.

 

Symptoms typically include fever, abdominal pain, and diarrhoea, but severe infections may require hospitalization.

When Water Becomes a Carrier of Disease

Food safety and water safety are closely connected.

Unsafe water used for drinking, cooking, washing food, or cleaning dishes can introduce harmful microorganisms into meals.

One of the most dangerous examples is Vibrio cholerae, the bacterium responsible for cholera.

The disease can cause severe diarrhoea and rapid dehydration.

Without prompt treatment, cholera can kill within hours.

Public health experts continue to emphasize that access to clean water and proper sanitation remains one of the most effective ways to reduce foodborne illnesses.

This is why food safety is closely linked to Sustainable Development Goal 3 (Good Health and Well-being) and Sustainable Development Goal 6 (Clean Water and Sanitation).

Yet some viruses spread through contaminated food and water.

• Norovirus

Often referred to as the “stomach flu,” Norovirus is one of the leading causes of foodborne illness globally.

The virus can spread rapidly through contaminated food, infected food handlers, or unsafe water.

Symptoms include nausea, vomiting, diarrhoea, and stomach cramps.

•  Hepatitis A

Hepatitis A can be transmitted through contaminated food and water, particularly in areas with poor sanitation.

The infection affects the liver and can cause fatigue, fever, abdominal discomfort, nausea, and jaundice.

Outbreaks are often linked to contaminated produce, shellfish, and unsafe water supplies.

The Overlooked Threat of Parasites

Parasites receive far less attention than bacteria and viruses, yet they remain a significant cause of foodborne disease.

Unlike bacterial infections that often appear quickly, parasitic infections may take weeks, months, or even years before symptoms become noticeable.

These organisms can enter the body through contaminated food, untreated water, undercooked meat, and poor hygiene practices.

Some parasites damage the digestive system.

Others can affect the brain, liver, or other vital organs.

In pregnant women, certain parasitic infections may also harm unborn children.

Because symptoms may appear long after exposure, many infections go undetected until serious damage has already occurred.

Food Poisoning Without Living Germs

Not all food poisoning is caused by living microorganisms.

Sometimes the danger comes from toxins already present in food.

A study by food safety researcher Shakila M. Banu explains that food intoxication occurs when people consume food containing toxins produced by bacteria, moulds, or other microorganisms.

Unlike infections, where bacteria multiply inside the body, intoxication occurs when toxins have already formed in the food before consumption.

Among the microorganisms commonly linked to food intoxication are:

•  Staphylococcus aureus
• Clostridium botulinum
• Bacillus cereus
• Clostridium perfringens

These toxins can trigger sudden symptoms including vomiting, diarrhoea, nausea, abdominal cramps, and weakness.

In severe cases, particularly with botulism, neurological symptoms such as blurred vision, muscle weakness, difficulty breathing, and paralysis may occur.

Chemical Hazards: The Threat Beyond Germs

Food can also become dangerous through chemical contamination.

Heavy metals such as lead, mercury, arsenic, and cadmium can enter the food chain through polluted soil, contaminated water, industrial activities, or improper processing methods.

Long-term exposure has been linked to cancers, cardiovascular diseases, kidney problems, developmental disorders, and neurological damage.

Mould toxins, particularly aflatoxins found in poorly stored grains, maize, groundnuts, and other staples, remain a significant concern in many developing countries.

Health experts have linked prolonged exposure to certain mycotoxins with liver cancer and growth impairment in children.

Symptoms You Should Never Ignore

Food poisoning symptoms vary depending on the cause, but some warning signs require immediate medical attention.

 

These include:

•  Persistent vomiting
•  Severe diarrhoea
• Signs of dehydration
• High fever
• Blood in stool
• Difficulty breathing
• Blurred vision
• Muscle weakness
• Confusion or loss of consciousness

 

Young children, pregnant women, older adults, and people with underlying health conditions are especially vulnerable and should seek medical attention promptly when symptoms become severe.

The stories of victims featured in Part One demonstrate a painful reality.

Understanding the invisible threats hidden in food and water is the first step toward protecting ourselves, our families, and our communities.

 

In Part Three of this series, nutrition expert and food entrepreneur Mrs. Victoria Ankinamia explains the everyday mistakes many households make in food handling and

storage—and why some of the biggest food safety risks may already be inside our kitchens.

Missed Part One? Read: He Never Made It to Dawn