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Study: Livestock Main Source of Food Poisoning

Sep 29, 2008 | Parker Waichman Alonso LLP

According to a study conducted by a group of researchers from the United Kingdom and United States, animals that are farmed for meat and poultry are the principle source of food poisoning in humans.  The research was published in PLoS Genetics.  Using a new method of evolution-based gene-typing, researchers found that 97 percent of the infections reviewed came through the food chain, specifically from chicken, cattle, and sheep; earlier studies pointed to wild animals or environmental sources.

Daniel Wilson of the University of Chicago and research lead, said the spread of the disease from campylobacteriosis—the disease caused by the campylobacter jejuni bacteria—could be reduced by improving food hygiene during preparation and by enforcing on-farm security measures. The campylobacter jejuni bacteria causes more cases of gastro-enteritis in the developed world than any other bacteria, including E. coli, Salmonella, Clostridium and Listeria combined.  “The dual observations that livestock are a frequent source of human disease isolates, and that wild animals and the environment are not, strongly support the notion that preparation or consumption of infected meat and poultry is the dominant transmission route,'' Wilson said.

Earlier research confirmed that campylobacter in humans most closely resembles non-livestock strains and some outbreaks may have been due to contaminated water.  In this research, the team—which included researchers from Chicago, Illinois and Lancashire, England—collected bacteria from 1,231 patients and also from wild and domestic animals and the environment.  The team then compared the genetic sequences of the samples, using the evolutionary modeling to source the human bacteria.   The team discovered most cases were caused by the spiral-shaped, campylobacter jejuni bacterium, which is typically found in chicken and livestock.

Wilson felt these results might prompt more work in the area of controlling food-borne pathogens and suggested some of the possibilities might include disinfecting farm premises and water supplies; restricting access to livestock to essential personnel only; minimizing invasive practices, such as thinning in chicken; securing premises from wild birds and mammals; and protecting food supplies from bacterial contamination.  A single drop of fluid from raw chicken meat can infect a person and one way for this transmission to occur is to cut poultry meat on a cutting board, and then use the unwashed cutting board or utensil to prepare vegetables or other lightly cooked or noncooked food.  The majority of the 2.4 million Americans who develop gastro-enteritis annually fall ill with campylobacteriosis from eating raw or undercooked poultry meat.

Campylobacteriosis causes diarrhea, which may be watery or sticky and can contain blood; fever; abdominal pain; nausea; headache; and muscle pain.  The illness generally occurs two-to-five days following contamination and may last as many as 10 days; however, relapses occur in about 25 percent of the cases.  Complications include reactive arthritis, hemolytic uremic syndrome (HUS), septicimia, and organ infection.  Death from Campylobacteriosis occurs in one of every 1,000 cases. Meningitis, recurrent colitis, acute cholecytitis, and Guillain-Barre syndrome are among the rare complications. Campylobacteriosis costs the U.S. economy over $4 billion, Wilson said.