Infectious diseases investigation

Certain infectious diseases are notifiable to the Health Authority and these are investigated by the consultant in communicable disease control (CCDC) or by officers of the Local Authority. We investigate food poisoning and certain other food borne illnesses, which are notifiable.

The purpose of this investigation is to try to prevent the spread of illness within the community and to try and establish possible causes. Advice is also given to the patient on how to prevent the spread of disease within the home.

Many different sorts of bacteria (germs) can cause food borne illness. When food is kept warm, these bacteria can grow rapidly and reach dangerous levels within hours. The numbers of cases of food borne illness have increased dramatically over the past few years, particularly during the Summer months. Good food hygiene standards in industry and the home are vital to prevent food borne illness.

The incubation period (time taken from eating the food to feeling unwell) varies with each type of organism and in some cases can be up to 10-15 days after consumption of the food. It is important to realise therefore, that the last meal you ate may not be the cause of your symptoms.

The main causes of food poisoning and food borne illness are:

• preparing foods too far in advance
• not cooking foods properly
• not defrosting foods correctly
• storing foods incorrectly (i.e. too warm) so that bacteria can grow quickly
• cross contamination of foods after cooking
• infection from people handling foods due to poor hygiene

Who is at Risk?

We all are, but babies, young children and the elderly can very quickly become very ill when infected. Pregnant women, people who already have a pre-existing illness, and anyone whose immune system is weakened can also be seriously affected by food borne illness.

What are the main symptoms of food-borne illness/food poisoning?

• diarrhoea
• stomach cramps
• vomiting
• fever
• nausea
• headache
• dizziness

There are many types of food borne illness caused by different bacteria. The most common include:

Campylobacter

Symptoms include stomach cramps and severe diarrhoea but rarely vomiting. They can begin 2-10 days after eating contaminated food but usually within 2-5 days. Main sources are undercooked chicken and other meats, handling pets, cross-contamination to other foods, raw milk and contaminated water. This organism is the most common cause of acute diarrhoea in adults.

Salmonella

Symptoms include stomach pain, fever, diarrhoea and vomiting. It usually takes about 12-48 hours for the illness to develop. Symptoms can be much more severe in the young and elderly. Main sources are undercooked meat and poultry, untreated milk and raw or undercooked eggs. This organism is the 2nd most common form of food poisoning.

E.coli 0157

Symptoms include severe bloody diarrhoea, and the infection can lead to serious kidney damage in children. Main sources are undercooked beefburgers and minced beef, contaminated cooked meats and unpasteurised milk. This organism has also been linked to farms

Staphylococcus aureus

Symptoms include stomach pains and vomiting, 1-6 hours after eating and it usually takes 12-24 hours for symptoms to subside. This bacteria is found on humans (particularly in the nose, throat, skin and ears) and is transferred to food through poor hygiene practices.

Listeria

Mild flu-like illness in healthy people, but which can cause septicaemia and meningitis in the young and elderly. Listeria can lead to stillbirth and miscarriage or meningitis in the new-born baby. Sources include unpasteurised soft cheeses (such as Brie and Camembert) and meat pates. Prevention of food poisoning from Listeria is more difficult than other organisms as it can multiply rapidly at refrigeration temperatures. It is recommended therefore that pregnant women do not eat the above products.

Prevention of food borne illness

Follow the Department's Top Ten Tips to try and reduce food borne illness:

• wash hands thoroughly before handling food and always after handling raw meat, going to the toilet, blowing your nose or handling animals (including pets)
• keep food preparation surfaces and utensils clean and disinfected (e.g. anti-bacterial).
• prepare and store raw meat and 'ready-to-eat' food separately. Always keep raw and defrosting meat at the base of the refrigerator, below everything else
• ensure that your refrigerator and freezer are operating properly, invest in a suitable thermometer. The refrigerator should operate at 5 degrees C or lower and the freezer at -18 degrees C or lower
• check the 'Use by' dates on food and ensure that you use the food before the date expires
• always store eggs in the refrigerator and do not eat food containing uncooked eggs
• keep pets away from food and food preparation surfaces
• defrost food, particularly meat and poultry thoroughly before cooking
• cook food thoroughly. Follow the manufacturers' guidelines and ensure that food is piping hot throughout before consumption
• cool food immediately after cooking and never allow it to be at room temperature for more than 4 hours. Always store left over food in the refrigerator as soon as it has cooled to room temperature

What to do if you have symptoms of food borne illness

Food borne illness can spread quickly, partly because everyone in the family could have eaten the same food and partly because the bacteria may be picked up by close family contact (e.g. nursing the sick). Viruses can also cause illness, similar to food poisoning and they also spread very quickly. If you suspect you are suffering food poisoning it is recommended that you visit your doctor as soon as possible, who might ask you to submit a sample for examination. Samples are useful in that they might be able to show which food-borne illness you are suffering from, or could rule out a food-poising organism. Viruses can also be detected. Consult your doctor immediately if the person affected is a baby, elderly or has an existing illness or condition or if symptoms are prolonged or severe (e.g. bloody diarrhoea).

If you or a member of your family are suffering from the symptoms of food poisoning, it is recommended that you follow the advice below to try and prevent the spread of the illness:

• wash your hands after contact with the sick person, and before handling food
• do not use the same towel or face cloth as someone who is suffering with food borne illness
• clear up soiling accidents straightaway, wash with hot soapy water and disinfect with a disinfectant or bleach
• disinfect door and toilet handles, taps and the toilet seat after use and disinfect the toilet bowl frequently
• drink plenty of fluids while you are ill to prevent dehydration