Approximately what percent of water troughs on cattle farms are contaminated with E. coli O157?

• A. 20 percent
• B. 2 percent
• C. 50 percent
• D. 0.2 percent

Answer: (A)

Contamination of water troughs with E. coli O157:H7 on cattle farms happens with enough frequency to be a notable risk, because cattle shed this pathogen in their feces and troughs can be contaminated during drinking or from splash and runoff. Surveys and prevalence studies have found that roughly twenty percent of troughs test positive for E. coli O157:H7. This rate shows that contamination is common but not universal, reflecting that factors like season, herd management, and cleaning practices influence how often troughs become contaminated. Warmer conditions can aid bacterial survival and shedding, while clean, well-maintained troughs with good water turnover reduce risk. In practice, reducing this risk means regular cleaning and disinfection of troughs, preventing fecal contamination, and ensuring a safe water source for cattle. The other suggested percentages would imply contamination rates that are either too rare or too widespread compared with typical field observations.