Food safety at home: preventing food poisoning in four steps

1. Introduction

Food poisoning, also called foodborne illness, happens when food contaminated with harmful germs or chemicals is eaten. The World Health Organization (WHO) estimates that about 866 million people, roughly 1 in 9 worldwide, fall ill from contaminated food each year, and that children under five carry a large share of the harm ^[1]. The good news is that many cases can be prevented with simple habits in the kitchen. This article uses information from WHO, the US Centers for Disease Control and Prevention (CDC) and the NHS.

2. Causes and risk factors

Food can be contaminated by bacteria such as Campylobacter, Salmonella, E. coli and Listeria, by viruses such as norovirus and hepatitis A, by parasites, and by chemicals including toxins and metals ^{[1, 3]}. The NHS explains that illness often follows undercooked or poorly reheated food, poor storage, food left out too long, handling by an ill person or unwashed hands, or eating food past its use-by date ^[3].

Some people are more likely to become seriously ill ^{[1, 2, 3]}:

• Children under five and babies
• Older people
• People with weakened immune systems or other conditions that raise the risk of dehydration
• Pregnant women. WHO notes that Listeria can cause miscarriage and that the parasite behind toxoplasmosis can harm an unborn baby ^[1]

The CDC lists riskier foods, including raw or undercooked meat, poultry, seafood and eggs, raw sprouts, unwashed fruits and vegetables, cut melon, unpasteurised milk, juice or soft cheese, and raw dough or batter made with uncooked flour ^[2].

3. Signs and symptoms

Symptoms depend on the germ, but the most common are diarrhoea, stomach pain or cramps, nausea, vomiting and fever ^{[1, 3]}. They usually start within a few hours to a few days of eating the food, although sometimes it takes a few weeks ^[3]. Cholera, caused by Vibrio cholerae, can cause heavy watery diarrhoea that leads quickly to severe dehydration ^[1]. Most cases are mild and clear up within about a week ^[3].

4. Preventing food poisoning

The CDC summarises prevention in four steps, and WHO's five keys to safer food carry the same messages ^{[2, 4]}.

Clean

• Wash your hands with soap and water for at least 20 seconds before, during and after preparing food, and before eating ^[2].
• Wash knives, boards and surfaces with hot, soapy water after each food item, and rinse fresh fruit and vegetables under running water ^[2].
• Do not wash raw chicken, because this can spread germs around the kitchen ^[2].
• WHO's keys also stress using safe water and safe raw ingredients ^[4].

Separate

• Keep raw meat, poultry, seafood and eggs away from ready-to-eat foods, in shopping bags and in the fridge ^{[2, 4]}.
• Use separate boards and plates for raw foods and for foods that will not be cooked ^[2].

Cook

• Cook food thoroughly. The CDC says a food thermometer is the only reliable way to know that food is done, and that colour and texture are not reliable, except for seafood ^[2].
• Reheat leftovers thoroughly, because food that is poorly reheated can cause illness ^{[2, 3]}.

Chill

• Do not leave perishable food out for more than 2 hours, or 1 hour in hot weather above 32 degrees Celsius (90 degrees Fahrenheit) ^[2].
• Put leftovers in shallow containers so that they cool quickly, and keep the fridge cold ^[2].
• Thaw food in the fridge, in cold water or in a microwave, and never on the kitchen counter ^[2].
• Do not eat food past its use-by date ^[3].

A few extra habits help. Check use-by dates, because eating food past its use-by date raises the risk of illness ^[3]. Food handled by someone who is unwell or has not washed their hands can carry germs, so avoid preparing food for others while you are unwell and wash your hands carefully ^[3]. If a product has been recalled, throw it away and clean the fridge where it was kept ^[2].

5. Home care

The NHS advises resting and drinking plenty of fluids, in small sips if you feel sick, and eating when you are able ^[3]. Keep breastfeeding or bottle feeding babies, offering small and frequent feeds, with formula at its usual strength ^[3]. Avoid fruit juice and fizzy drinks, which can make diarrhoea worse ^[3]. A pharmacist can advise on oral rehydration powders, which replace lost fluids and salts, and on other treatments ^[3]. Do not give anti-diarrhoea medicines to children under 12 or aspirin to children under 16 ^[3].

6. When to see a doctor

Seek medical advice promptly if you have bloody diarrhoea, diarrhoea lasting more than 7 days, vomiting lasting more than 2 days, or you cannot keep fluids down ^[3]. Get help for any baby under 12 months, any child who stops feeding, and anyone showing signs of dehydration, such as dark, strong-smelling urine or passing less urine ^[3]. Older adults and people with weak immune systems or conditions that raise the risk of dehydration should speak to a pharmacist or doctor early ^[3]. Pregnant women are also at higher risk of serious illness, so seek advice early ^[1].

Get emergency help for blood in vomit or vomit that looks like coffee grounds, a stiff neck with sensitivity to light, sudden severe headache or tummy pain, blue, grey or pale skin, severe difficulty breathing, or confusion ^[3]. Do not drive yourself to hospital ^[3].

In an emergency, call your local emergency number (112 in India, 911 in the United States).

7. Conclusion

Food poisoning is common and usually passes within a week, but it can be serious for babies, older adults, pregnant women and people with weak immune systems. Cleaning, separating, cooking and chilling food correctly helps prevent many cases, and fluids are the mainstay of home care.