Research Shows Cattle Are Infected With E. coli Mostly in Summer

Read more about recent ARS research to combat E. coli:

• Minimizing Microbes on Fresh-Cut Foods (June 1999)
• Pasteurizing Manure (Sept. 1999)
• Keeping E. coli, Parasites Out of Drinking Water (Nov. 1999)
• Carbonating Manure (Feb. 2000)
• Jellyfish Gene Lights Up E. coli (Mar. 2000)

In late summer, up to 28 percent of cattle entering processing plants may carry with them strains of the E. coli bacterium that cause food poisoning in humans, according to an Agricultural Research Service study.

Improved laboratory methods allowed the scientists to ferret out the microbe and detect this prevalence level, which is higher than previously reported. But the research also showed that intervening measures at processing plants can reduce the incidence of E. coli 0157:H7 on beef carcasses to less than 2 percent even in the peak contamination season of July and August.

The study will be published in the Proceedings of the National Academy of Sciences on March 28.

The study, conducted by scientists at the ARS Roman L. Hruska U.S. Meat Animal Research Center (MARC), Clay Center, Neb., included examination of E. coli shed in the feces of live cattle as well as microbes on beef carcasses in commercial processing plants.

During the summer E. coli peak, 28 percent of the live cattle entering the processing plants were actively shedding E. coli 0157:H7 in their feces and 43 percent of 341 carcasses were initially contaminated with the bacterium. Eleven percent of hide surfaces were also contaminated with the bacterium. After processing was complete, only six of 330 carcasses, or 1.8 percent, showed some level of contamination.

ARS is the USDA's chief scientific agency.

Scientific contact: Danny B. Laster, ARS Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, Neb., phone (402) 762-4109, fax (701) 762-4111, laster@email.marc.usda.gov.