November 9, 1996
Arthritic food poisoning
Ordinarily, food poisoning causes little more than an intense though short-lived bout of intestinal distress -- often
including vomiting, diarrhea, and sometimes a headachy fever. However, microbiologist James L. Smith says, "I am a firm
believer that food poisoning is more than a simple inconvenience," especially for that small share of the sufferers who
go on to develop additional, more lasting discomfort, such as reactive arthritis.
Since retiring from federal service with the Agricultural Research Service 6 years ago, he's been researching the link
between food poisoning and this disease at his former agency's Microbial Food Safety Research Unit, in Wyndmoor, Pa.
Most bacterially triggered arthritis traces to germs that infect the joints. As the bugs multiply, they cause a local
inflammation and destruction of joint tissue. With the food poisoning bacteria Campylobacter, Salmonella, Shigella, and
Yersinia, a different arthritis may occur. Here, affected joints harbor no germs, only some toxins the bacteria produce.
Our immune systems target the toxins for destruction, often with mechanisms that provoke local inflammation.
This Salmonella bacterium, just half a millionth of a meter wide, can cause gut-wrenching food poisoning.
Human leukocyte antigens (HLAs) are a family of proteins that occur on the surface of most body cells and blood
platelets. The immune system uses these markers to distinguish between materials that belong in the body and those
that are foreign. It is a mismatch between the body's HLAs and those on organ transplants that can trigger tissue-graft
rejection, for instance.
For reasons no one quite understands, individuals carrying the gene responsible for producing an antigen known as
HLA-B27 inherit a genetic predisposition to arthritis, especially to degenerative joint inflammation following a
food-poisoning incident. There has been some suggestion that the HLA-B27 antigen may resemble the toxins, which can
also be considered antigens, formed during infection with any of the four food-poisoning microbes, Smith observes, and
that "this antigen mimicry could be the mechanism for causing arthritis."
Who carries the gene? About 10 percent of U.S. whites, 4 percent of North American blacks, and 1 percent of Japanese,
Smith says. So far, he notes, the gene appears totally absent in the blacks of Africa and Australia.
However, the genetic link is not iron clad. Many food-poisoning victims carrying the HLA-B27 gene "will not get arthritis,
and many who are not positive [for this gene] will be afflicted," Smith told Science News Online. Overall, about 10
percent of individuals with the gene who get diarrhea as a result of food poisoning go on to develop reactive arthritis -- 5
times the rate observed among persons without the gene. Moreover, Smith notes, persons with the HLA-B27 gene tend
to develop more severe arthritis.
Ironically, Smith says, because "a severe bout of diarrhea leads to quick cleansing of the bowel" -- eliminating foodborne
germs -- "it would appear that a mild case of gastroenteritis is more likely to lead to arthritis."
The good news is that these bacterially induced cases of joint pain tend not to be permanent, instead last just weeks to
months. "But do remember," Smith points out, "another food poisoning incident may lead to a new bout of arthritis."
Overall, an estimated 2 percent of food poisoning victims develop reactive arthritis. According to a U.S. General
Accounting Office report issued in May, foodborne Campylobacter and Salmonella may each poison some 1.5 million
people in the United States each year. That would put the arthritic toll from these two diseases alone at somewhere in
the neighborhood of 60,000 cases annually. According to Japanese scientists writing in the Annals of the Rheumatic
Diseases earlier this year, toxins of some of these same microbes also appear capable of triggering rheumatoid arthritis
in genetically susceptible people.
Because mild food poisoning may go unrecognized -- and certainly unreported (see Lessons from a case of toxic ice
cream) -- the actual number of persons at risk of this aftermath of food contamination may be far higher still.
Indeed, such numbers provide further impetus to fight foodborne germs in kitchens (see How to disinfect your salad, and
Sponges and Sinks and Rags, Oh My!) and the marketplace.
Aoki, S., et al. 1996. Role of enteric bacteria in the pathogenesis of rheumatoid arthritis: Evidence for antibodies to
enterobacterial common antigens in rheumatoid sera and synovial fluids. Annals of the Rheumatic Diseases 55:363.
Smith, J.L. 1994. Arthritis and foodborne bacteria. Journal of Food Protection 57(October):935.
Smith, J.L., S.A. Palumbo, and I. Walls. 1993. Relationship between foodborne bacterial pathogens and the reactive
arthritides. Journal of Food Safety 13:209.
Stanley, D. 1996. Arthritis from foodborne bacteria? Agricultural Research 44(October):16.
1996. Food safety: Information on foodborne illnesses. Report RCED-96-96 (May). U.S. General Accounting Office,
Washington, DC 20548-0001.
Armstrong, G.L., J. Hollingsworth, and J.G. Morris, Jr. 1996. Emerging foodborne pathogens: Escherichia coli O157:H7
as a model of entry of a new pathogen into the food supply of the developed world. Epidemiologic Reviews 18:29.
Blumenthal, D. 1990. Salmonella enteritidis. FDA Consumer 24 (April):6.
Cliver, D.O. 1993. Eating safely: Avoiding foodborne illness. American Council on Science and Health, (1995 Broadway,
2nd Fl., New York, NY 10023-5860. Ph: 212-362-7044; FAX: 212-362-4919. E-mail: email@example.com).
Fackelmann, K. 1996. Gastrointestinal blues. Science News 150(Nov. 9):302.
Raloff, J. 1996. Tracking and tackling foodborne germs. Science News 149(May 25):326.
1994. Foodborne pathogens: Risks and consequences. CAST Task Force Report No. 122 (September), Council for
Agricultural Science and Technology (4420 W. Lincoln Way, Ames, IA 50014-3447. Ph: 515-292-2125; FAX:
800-375-CAST. E-mail: firstname.lastname@example.org).
James L. Smith
USDA-ARS Microbial Food Safety Research Unit
Eastern Regional Research Center
600 E. Mermaid Lane
Wyndmoor, PA 19038-8551
This week's Food for Thought is prepared by Janet Raloff, senior editor of Science News.