Salmonella and food poisoning

Reviewed by Dr Dan Rutherford, GP

What is salmonella?
Salmonella is a type of bacteria. It is usually found in poultry, eggs, unprocessed milk and in meat and water. It may also be carried by pets like turtles and birds.

What kind of infection does salmonella cause?
The salmonella bacteria attacks the stomach and intestines. In more serious cases, the bacteria may enter the lymph tracts, which carry water and protein to the blood, and the blood itself. The bacteria attack all age groups and both sexes. Children, the elderly and people who are already ill are much more likely to get a serious infection.

What are the symptoms of salmonella poisoning?

• Diarrhoea or constipation.
• Headaches.
• Stomach cramps.
• Nausea and vomiting.
• Fever.
• Possibly, blood in the faeces.

In the case of less serious infections there are fewer symptoms - usually only diarrhoea two or three times a day for a couple of days. Most mild types of salmonella infection clear up in four to seven days without requiring any treatment other than rest and plenty of liquid.

A more severe infection may cause excessive diarrhoea, stomach cramps and general health problems. In such cases, treatment with antibiotics may be necessary and a doctor should be consulted.

When is it necessary to contact a doctor?

• If diarrhoea continues for more than 24 hours.
• If the diarrhoea is frequent and intense.
• If the patient has severe stomach cramps.
• If there is blood in the faeces.
• If the patient has fever of 38oC or higher.
• If there are signs of jaundice - a yellowish discolouration of the skin or eyes. This may indicate problems with the liver or the bile ducts that take the bile from the liver to the stomach.
• Dehydration.

What is the danger of dehydration?
Frequent diarrhoea and vomiting may drain the body of fluids, salts and minerals. Dehydration occurs when the patient loses more liquid than they can take in. Cases of dehydration should always be checked by a doctor and can be very dangerous in babies and the elderly.

Signs of dehydration are:

• the tongue or the mucous membranes in the mouth are dry
• dry, chapped skin
• increased thirst
• dark urine
• lack of, or decreased, urine output
• weakness.

How can salmonella infections be prevented?

• Pay attention to cleanliness.
• Make sure that all food is thoroughly cooked.

What are the basic rules for preparing food hygienically?

• Always wash your hands with soap after going to the toilet and before preparing food. Dry them on a dry towel.
• Wash your hands when you switch from preparing one type of food to another, eg vegetables to meat. This helps prevent the exchange of bacteria between different ingredients.
• Kitchen utensils must be properly washed with soap and water before use with another type of food. Again, this stops bacteria being exchanged.
• Use different cutting boards and knives for preparing different foods.
• Change the dishcloth every day. Wash dishcloths in water that is at least 60oC.
• Store food in the refrigerator. Meat, poultry and fish must not be left out of the fridge for long periods.

. How should food be cooked to avoid salmonella poisoning?
The only effective way to kill salmonella bacteria is with heat. For this reason it is essential to cook food thoroughly.

• Poultry must always be thoroughly cooked or boiled.
• Minced meat must always be thoroughly cooked or boiled.
• Never crack a raw egg on a bowl containing other foods - use a knife to crack the shell.
• In most eggs, the salmonella bacteria exist only on the shell. Eggs should be scalded in boiling water for five seconds before use.

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