Access to safe and nutritious food is fundamental for maintaining life and promoting good health. However, unsafe food contaminated with harmful bacteria, viruses, parasites, or chemical substances can lead to over 200 diseases, ranging from diarrhea to cancer. This creates a cycle of disease and malnutrition, especially affecting infants, young children, the elderly, and those already ill. Ensuring food safety and strengthening food systems requires collaboration between governments, food producers, and consumers. Determining Are The Items Of Food Handling Most Likely to cause illness is crucial in preventing these diseases.
Major Foodborne Illnesses and Causes
Foodborne illnesses are typically infectious or toxic, caused by bacteria, viruses, parasites, or chemical substances entering the body through contaminated food. Chemical contamination can result in acute poisoning or long-term conditions like cancer. Many foodborne diseases can lead to lasting disability and even death.
Bacteria
Salmonella, Campylobacter, and enterohaemorrhagic Escherichia coli are among the most prevalent foodborne pathogens, affecting millions each year and sometimes leading to severe or fatal outcomes. Symptoms may include fever, headache, nausea, vomiting, abdominal pain, and diarrhea. Outbreaks of salmonellosis are frequently linked to eggs, poultry, and other animal products. Campylobacter infections are mainly caused by raw milk, raw or undercooked poultry, and contaminated drinking water. Enterohaemorrhagic Escherichia coli is often associated with unpasteurized milk, undercooked meat, and contaminated fresh fruits and vegetables.
Alt text: Microscopic view of E. coli bacteria, highlighting a common source of foodborne illness.
Listeria infections can lead to miscarriage in pregnant women or death of newborn babies. Despite the relatively low occurrence, the severe and sometimes fatal health consequences of Listeria, particularly among infants, children, and the elderly, make it a serious foodborne infection. Listeria is found in unpasteurized dairy products and various ready-to-eat foods and can grow at refrigeration temperatures.
Vibrio cholerae can infect people through contaminated water or food. Symptoms may include abdominal pain, vomiting, and profuse watery diarrhea, potentially leading to severe dehydration and death. Raw vegetables and various types of raw or undercooked seafood have been implicated in cholera outbreaks.
Antimicrobials, like antibiotics, are essential for treating bacterial infections, including foodborne pathogens. However, their overuse and misuse in both veterinary and human medicine have contributed to the emergence and spread of resistant bacteria, rendering infectious disease treatments ineffective in animals and humans.
Viruses
Certain viruses can be transmitted through food consumption. Norovirus is a common cause of foodborne infections, characterized by nausea, explosive vomiting, watery diarrhea, and abdominal pain. Hepatitis A virus can also be transmitted via food, causing long-lasting liver disease, typically spreading through raw or undercooked seafood or contaminated raw produce.
Alt text: Illustration of contaminated shellfish, a known vector for hepatitis A virus transmission through food.
Parasites
Some parasites, such as fish-borne trematodes, are exclusively transmitted through food. Others, like tapeworms such as Echinococcus spp or Taenia spp, can infect people through food or direct contact with animals. Other parasites, including Ascaris, Cryptosporidium, Entamoeba histolytica, or Giardia, enter the food chain via water or soil and can contaminate fresh produce.
Prions
Prions, infectious agents composed of protein, are unique due to their association with specific forms of neurodegenerative disease. Bovine spongiform encephalopathy (BSE, or mad cow disease) is a prion disease in cattle, linked to variant Creutzfeldt-Jakob disease (vCJD) in humans. Consuming meat products containing specified risk material, such as brain tissue, is the most likely route of transmission of the prion agent to humans.
Chemicals
The most significant health concerns related to chemicals in food are naturally occurring toxins and environmental pollutants.
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Naturally occurring toxins include mycotoxins, marine biotoxins, cyanogenic glycosides, and toxins found in poisonous mushrooms. Staple foods like corn or cereals can contain high levels of mycotoxins, such as aflatoxin and ochratoxin, produced by mold on grain. Long-term exposure can affect the immune system and normal development, or cause cancer.
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Persistent organic pollutants (POPs) are compounds that accumulate in the environment and the human body. Examples include dioxins and polychlorinated biphenyls (PCBs), unwanted by-products of industrial processes and waste incineration. Found worldwide in the environment, they accumulate in animal food chains. Dioxins are highly toxic and can cause reproductive and developmental problems, damage the immune system, interfere with hormones, and cause cancer.
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Heavy metals, such as lead, cadmium, and mercury, cause neurological and kidney damage. Contamination by heavy metals in food mainly occurs through the pollution of water and soil.
Other chemical hazards in food can include radioactive nucleotides discharged into the environment from industries and civil or military nuclear operations, food allergens, residues of drugs, and other contaminants incorporated during processing.
The Burden of Foodborne Diseases
The burden of foodborne diseases on public health and economies is often underestimated due to underreporting and difficulty establishing causal links between food contamination and resulting illness or death.
The 2015 WHO report on global foodborne disease estimates highlighted that more than 600 million cases of foodborne illnesses and 420,000 deaths occur annually. Vulnerable populations, especially children under 5, bear a disproportionate burden, with the highest impact in low- and middle-income countries.
The 2019 World Bank report on the economic burden of foodborne diseases estimated the total productivity loss at US$ 95.2 billion per year in low- and middle-income countries, with annual treatment costs estimated at US$ 15 billion.
The Evolving World and Food Safety
Safe food supplies are vital for health, contribute to food and nutrition security, support national economies, trade, and tourism, and underpin sustainable development.
Urbanization and changing consumer habits have increased the number of people buying and eating food prepared in public places. Globalization has led to a growing consumer demand for a wider variety of foods, resulting in a complex and extended global food chain.
Alt text: Visual representation of a complex global food supply chain, highlighting various stages from production to consumption and related food safety considerations.
Climate change is expected to significantly impact food safety, increasing risks from existing and emerging foodborne diseases through more frequent extreme weather events, rising air and water temperatures, and changes in precipitation patterns.
These challenges place greater responsibility on food producers and handlers to ensure food safety. Local incidents can quickly escalate into international emergencies due to the speed and scope of product distribution.
A Public Health Priority – From Farm to Fork
Governments must prioritize food safety as a public health issue, developing evidence-based policies and risk-based, flexible regulatory frameworks, and establishing and implementing effective food safety systems. Food handlers and consumers need to understand how to handle food safely and practice the WHO Five Keys to Safer Food at home or when selling at restaurants or local markets. Food producers can safely grow fruits and vegetables using the WHO Five Keys to Growing Safer Fruits and Vegetables.
Food safety is a shared responsibility among different national authorities, requiring a multisectoral, One Health approach, addressed at all steps of the food chain.
WHO Response
WHO aims to strengthen national food control systems to facilitate global prevention, detection, and response to public health threats linked to unsafe food. To achieve this, WHO supports Member States by working closely with the Food and Agriculture Organization (FAO), the World Organisation for Animal Health (WOAH), the UN Environment Programme (UNEP), and other international organizations to ensure food safety across the entire food chain from production to consumption, aligning with the One Health Joint Plan of Action (2022–2026).
