Food Poisoning – Causes, Symptoms & Prevention Strategies
The term Food Poisoning covers a wide range of conditions, from minor illnesses through to life-threatening or fatal infections. Generally speaking, these conditions are caused by ingesting foodstuffs that contain or have been contaminated with a harmful bacteria or virus.
For most of us, a bout of food poisoning will result in at most a couple of days of discomfort, with relatively minor symptoms such as nausea, vomiting, diarrhoea and stomach cramps. Usually this does not require medical intervention, and recovery requires only a period of rest with careful attention to diet.
In some cases however, the symptoms can be much more severe, leading to serious dehydration, fever and in certain cases even proving fatal. As many illnesses, certain groups such as the very young or elderly are at risk of more serious effects, as well as individuals lacking access to basic first aid, clean water or proper sanitation.
In the developed world, the incidence of severe cases of food poisoning has been significantly reduced due to better preservation, storage and handling of food, increased public awareness about the risks, and improved sanitation, however in less economically developed countries, or during wars or natural disasters, the problem is often widespread.
Food Poisoning Statistics
Developed countries report very low levels of serious illness or death due to food poisoning, with annual deaths per 100,000 inhabitants reported as 1 in the US, 0.8 in the UK, 0.75 in France and 0.5 in Australia, and annual hospitalisations as 43, 28, 182 and 87 respectively.
A 2015 study by the World Health organisation estimates that 10% of people worldwide will fall ill with a foodborne disease each year, leading to 420,000 deaths – 7 to 10 times higher than in the countries mentioned above. The highest number of deaths are reported in the poorest regions, 175,000 in SE Asia and 137,000 in Africa.
Outbreaks & Common Causes
Outbreaks of serious food poisoning can often spread quickly within populations, due to contaminated water sources, poorly prepared or stored food, contact with infected animals or spread from person to person due to poor personal hygiene or lack of access to sanitation. Some of the more common contaminants and types of food poisoning are listed below:
Escherichia coli (E. coli)
E. coli is commonly present in human intestines, but certain strains of the bacteria can be a cause of food poisoning. In most cases E. coli causes diarrhoea, abdominal pain, and fever which subside within a few days. In sever cases though, the infection can lead to can lead to severe dehydration, bloody stools and even kidney failure.
Salmonella is often found in dairy products, eggs and poultry which has been improperly cooked, and produces classic food poisoning symptoms in its mildest form. However, severe infections can spread from the digestive tract to the bloodstream, and some forms of the bacteria can even cause typhoid fever.
Campylobacter is one of the most commonly found contaminants in the UK, causing symptoms a few days after ingestion and lasting from two days to a week. The bacteria is usually found in contaminated water or raw or undercooked poultry.
Listeria bacteria often contaminate unpasteurised cheeses, poultry, meat, fish and raw fruit and vegetables, and can also be found in soil. While symptoms are usually mild and disappear within a few days, severe cases can exhibit a fatality rate of up to 25%.
Shigella is closely related to Salmonella, and is one of the leading global causes of dysentery resulting in between 100,000 and 600,000 deaths per year, principally in Africa and South East Asia. In rare cases it can also cause seizures in young children and reactive arthritis in adults.
Also known as the ‘winter vomiting bug’, Norovirus is usually transmitted by person to person contact, or fecal contamination of food or water. While most cases result in minor illness for two to three days, as with all foodborne illness, the effects are often more severe in vulnerable individuals.
Most illness caused by Rotavirus occurs in children, as immunity to the virus develops relatively quickly. It is generally less severe in developed countries, presenting as a mild fever with vomiting and diarrhoea, particularly where vaccination programmes are in place. Globally however it is responsible for 37% of all child deaths from diarrhoea and is highly contagious..
As well as bacteria and viruses, parasites can also cause food poisoning, usually due to toxins excreted into the body of the host. While rare in the developed world, parasitic infections such as cryptosporidiosis, giardiasis and ameobiasis, or ameobic dysentery are common in the developing world.
Prevention and Treatment
Reducing or preventing food poisoning requires a high standard of both personal and food hygiene, and as has been mentioned above, the challenges to prevention increase in regions with less reliable sanitation, health infrastructure and public education programmes.
One key area is food storage, handling and preparation. Maintaining strict standards of hygiene in the butchering and transport of meat and the washing and storage of fruits and vegetables can eliminate many harmful contaminants.
Chilling, freezing or preserving food helps to eliminate bacterial growth, and careful separation of raw and cooked foods is necessary to reduce cross contamination. Use by dates are important in helping to identify food which may have become contaminated, even if this is not immediately apparent by its appearance or odour.
Regular hand washing and cleaning of kitchen implements and surfaces is also an important factor in preventing the spread of foodborne illness, as well as ensuring that people exhibiting symptoms of food poisoning do not prepare or handle food.
On a wider level, the provision of clean water supplies and properly managed sewage and sanitation facilities is crucial to preventing large outbreaks of illness, as well as regulation of food hygiene standards and proper packaging and labelling.
Vaccination has also been used in some cases to prevent the spread of particular food borne illnesses, particularly rotavirus, although many of the pathogens which cause food poisoning adapt over time, and can render vaccines ineffective eventually.
This ability of viruses and bacteria to evolve resistance also means that health authorities are reluctant to treat food poisoning with antibiotics, especially when symptoms are relatively minor.
Overall, as the saying goes “prevention is better than the cure” – and organisations such as the WHO devote much of their time to public education programmes aimed at assisting people all over the world to identify and avoid the risks associated with these types of illness.