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CPRC Update: November 2009

Campylobacter jejuni


October 27, 2009
By CPRC

Topics

Campylobacter jejuni (C. jejuni) is the most common cause of bacterial
gastroenteritis (inflammation of the stomach and the intestines) in
humans in North America.

What is Campylobacter Jejuni?
Campylobacter jejuni (C. jejuni) is the most common cause of bacterial gastroenteritis (inflammation of the stomach and the intestines) in humans in North America. Infection with the bacterium (referred to as campylobacteriosis) can cause nausea, vomiting and/or diarrhea. While this illness can be severely debilitating, it is rarely life threatening. Most people recover from C. jejuni infections in a week or so; however, on rare occasions some may develop arthritis or Guillain-Barré syndrome, a disease affecting the nerves of the body that can cause muscle paralysis for several weeks and usually requires intensive hospital care. It is estimated that one in every 1,000 reported cases of campylobacteriosis leads to Guillain-Barré syndrome. Campylobacter jejuni has a low infectious dose; only 500 organisms or less are required in order to cause illness.

Where is it Found?
Campylobacter jejuni? is commonly found in the intestines of poultry, cattle, swine, rodents, wild birds and household pets such as cats and dogs. It has also been found in untreated surface water (caused by fecal material in the environment) and manure. Humans may develop campylobacteriosis after consuming substances infected by the bacterium. Despite its prevalence, relatively little is known about the biology of C. jejuni, particularly about its ability to cause disease.

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Campylobacter and Poultry
Many strains of C. jejuni are well adapted to birds, whose relatively high body temperature allows for optimal growth of the bacterium. Certain strains are particularly adept at colonizing the avian gut. Poultry harbour C. jejuni in their gut without showing signs of illness and therefore act as a natural reservoir for the bacterium. Poultry products contaminated with C. jejuni are implicated as a source of human infection. While the risk of human illness can be greatly reduced by proper handling and cooking of poultry products, researchers in Canada and abroad are looking for ways to reduce numbers of C. jejuni at the source to further reduce the risk of foodborne illness.

Campylobacter Research
Research interest in C. jejuni has increased in recent years as a result of the growing appreciation of its importance as a pathogen and due to the availability of new model systems and genetic and genomic technologies to facilitate its study.  There is a growing body of work that is utilizing these new technologies to determine the genetic differences in strains of C. jejuni. The idea here is to link the presence of certain genes, classified as “virulence” genes, with a strain’s ability to colonize the gut. A better understanding of why certain strains of C. jejuni colonize the gut more efficiently than others could lead to ways of controlling these virulent strains.

Dr. Brenda Allan at the Vaccine and Infectious Disease Organization (VIDO) in Saskatchewan is leading a research team that is looking at these strain differences with an eye towards the long-term goal of developing a vaccine to decrease the level of C. jejuni in poultry. A number of genes have been identified which may be linked to C. jejuni’s ability to colonize the poultry gut. Dr. Allan’s group looked at 49 C. jejuni samples from cattle and 50 from humans and screened them for the presence of 14 putative virulence genes.  Results of this screen were compared to previous results on C. jejuni samples from poultry. The researchers found that bovine (cow) and human isolates commonly carry virulence genes that are involved in colonization of poultry. Animal challenge studies showed that selected bovine and human isolates were able to efficiently colonize young broiler chicks. These data suggest that bovine species may serve as an important source of C. jejuni to colonize poultry. The information contributes to the increasing knowledge base on the biology of C. jejuni,  its interactions with its animal hosts, and its ability to cause disease. It is hoped that a better understanding of C. jejuni will lead to better ways to limit its impact on food safety and human illness.

Information Sources
Background information on C. jejuni was obtained from the Canadian Food Inspection Agency (www.inspection.gc.ca) and the Food Safety Network (www.foodsafetynetwork.ca). 

Dr. Allan’s research was funded by the CPRC as part of the Avian Gut Microbiology Network, which is aimed at promoting a better understanding of the dynamics of poultry gut microbes and their impact on poultry health and food safety.

For more details on any CPRC activities, please contact Gord Speksnijder at The Canadian Poultry Research Council, 483 Arkell Road, R.R. #2, Guelph, Ontario, N1H 6H8, phone: (289) 251-2990, fax: (519) 837-3584, e-mail: info@cp-rc.ca, or visit us at www.cp-rc.ca.

The membership of the CPRC consists of the Chicken Farmers of Canada, Canadian Hatching Egg Producers, Turkey Farmers of Canada, Egg Farmers of Canada and the Canadian Poultry and Egg Processors’ Council. CPRC’s mission is to address its members’ needs through dynamic leadership in the creation and implementation of programs for poultry research in Canada, which may also include societal concerns.


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