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What is Campylobacter?

Campylobacter is a naturally occurring bacterium found in the intestinal tract of wild and domesticated birds and mammals. It is the most common cause of bacterial gastroenteritis in Ireland and Europe.

What illness does it cause?

Campylobacteriosis is the illness caused by Campylobacter species. Campylobacter jejuni is the predominant species associated with human illness, other species being Campylobacter coli and Campylobacter lari.

Most people who become ill get diarrhoea, cramping, abdominal pain, and fever within 2 to 5 days after exposure to the organism. The diarrhoea may be bloody and can be accompanied by nausea and vomiting. The illness typically lasts one week. Some infected people do not have any symptoms. In people with compromised immune systems, the Campylobacter occasionally spreads to the bloodstream and causes a serious life-threatening infection.

Complications are rare, but infections have been associated with reactive arthritis, Reiter’s syndrome, or Hemolytic Uremic Syndrome (HUS) and approximately 1 in 1000 cases lead to a neurological disorder called Guillain-Barré Syndrome.

The infective dose (i.e. the number of cells required to cause infection) is quite low, ranging from 500 to 10,000 cells. 

How common is it?

In Ireland, 2,388 cases of campylobacteriosis were reported to the Health Protection Surveillance Centre in 2012. This represents an annual incidence rate of 52 cases per 100,000 of the population, nearly 8 times the incidence of salmonellosis (7 cases per 100,000). As many cases go unreported to health authorities, the actual or real incidence is likely to be much higher. The European average annual incidence for campylobacteriosis reported in 2012 was 56 cases per 100,000.

How does food or water become contaminated with Campylobacter?

In the case of food animals Campylobacter seems to be most commonly found in poultry flocks. These birds rarely show signs of illness. Campylobacter can be easily spread from bird to bird through a contaminated water source or through contact with faeces. When an infected bird is slaughtered, Campylobacter in the bird’s intestines can contaminate the meat.

Unpasteurised milk can become contaminated through contact with an infected cow’s udder or contact with faeces. Surface water can become contaminated by faeces from infected cows or wild birds.

How do people become infected?

Most cases of infection are thought to result from handling raw poultry or eating undercooked poultry meat. It doesn’t take many bacteria to cause illness (as few as 500 can be enough) and this can mean that even a drop of juice from raw chicken could make someone ill. One common way for infection to be spread is when raw poultry is prepared on work surfaces (including chopping boards) that are used to prepare foods which will not be cooked (e.g. salads) without being properly washed in between. Contamination can then pass from the raw meat to ready-to-eat foods. Handling raw poultry and then handling a ready-to-eat food, without washing hands can result in contamination of the ready-to-eat food.

Drinking contaminated untreated water or unpasteurised milk may also lead to campylobacteriosis. Person to person spread is unusual but has been reported. Infection may also be spread from an infected dog or cat. Outbreaks of campylobacteriosis are rare and when they do occur they tend to be small family outbreaks associated with contaminated food.

How can it be controlled?

Strategies to control Campylobacter spp. in food are required at all stages of the food chain, i.e. from farm to fork.

At farm level, efforts should be aimed at reducing or eliminating colonisation of live animals with this organism through good agricultural practices and by employing strict biosecurity measures in the case of poultry flocks.

Food safety management systems in poultry plants and abattoirs should be designed to prevent or control contamination of meat from the skin/hides or alimentary tract of infected birds/animals.

Retailers and caterers must ensure that opportunities for cross-contamination between raw poultry and ready-to-eat foods are eliminated. Retailers should ensure that poultry is sold in packaging that does not easily leak as a study by FSAI has found contamination on the surface of chicken packaging in Irish retail outlets. Hands and utensils should always be washed after handling raw poultry, and poultry should be cooked thoroughly until there is no pink meat and the juices run clear.

What can consumers do?

Consumers can protect themselves by:

  • using a separate bag for packing raw poultry and raw meats when shopping
  • washing hands with soap before and after preparing or handling raw poultry and meat and before touching anything else 
  • not washing oven ready birds (as this can spread Campylobacter around the kitchen)
  • freezing raw poultry and meat, as this reduces the number of Campylobacter
  • cooking all poultry products thoroughly (the meat is cooked properly when it is no longer pink and the juices from deep inside the meat run clear) 
  • preventing cross-contamination in the kitchen by not using the same chopping board for raw meat/poultry and other foods
  • washing all chopping boards, work surfaces and utensils with soap and hot water after preparing raw poultry and meat 
  • avoiding drinking unpasteurised milk and untreated surface water
  • making sure that people with diarrhoea (especially children) wash their hands carefully and frequently with soap to reduce the risk of spreading infection 
  • washing hands with soap after having contact with pets and their droppings.