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Photo: Scientists analyze dendograms to determine epidemiological relationships of Icelandic poultry and human Campylobacter isolates. Link to photo information

Read: a more detailed story on the research in Agricultural Research.

Campylobacter Mystery Moves Toward Resolution

By Sharon Durham
June 14, 2001

A variation on the age-old question of which came first--the chicken or the egg-- is one Agricultural Research Service scientists are pondering as they search for the source of a foodborne bacteria that causes human illness. The scientific riddle the researchers want to solve is how each new generation of chicks is infected with Campylobacter.

To find the answer, ARS researchers traveled to Iceland, where poultry is produced in a closed system. Breeder eggs are obtained from Sweden, hatched in Iceland and quarantined at rearing farms. It is an integrated approach with a high degree of control.

ARS scientist Norman Stern and his colleagues at the Poultry Microbiological Safety Research Unit, Athens, Ga., believe they have found one major source of Campylobacter: the fertile chicken egg. Historically, possible sources of the bacteria were thought to be the feed, wild birds, well water, bird fluff and pads in the cages.

Through inoculation studies, scientists showed that Campylobacter couldn't survive long in dry conditions, eliminating bird feathers and hatchery transport paper pads from the list of possible sources. Other studies showed that feces on the surface of eggs were an unlikely source of contamination. Thus, attention focused on transmission of the bacteria in the egg itself.

By sequencing genetic material called DNA, a specific gene in Campylobacter was isolated and used as a marker to identify identical organisms. Evidence shows that the same Campylobacter isolate was detected in poultry production plants about 20 miles apart. The only way the organism was able to travel from one location to the other was in the moist confines of the egg.

The research may lead to understanding the major sources involved in transmitting the bacteria--and may help reduce or prevent Campylobacter from entering the marketplace.

A more detailed story on the research appears in June 2001 issue of Agricultural Research magazine.

ARS is the chief scientific research agency of the U.S. Department of Agriculture.

Scientific contact: Norman Stern, Poultry Microbiological Safety Research Unit, ARS Richard B. Russell Research Center, Athens, Ga., phone (706) 546-3516, fax: (706) 546-3771,