Approximately what percentage of pig farms in the United States have tested positive for Salmonella enteritidis?

• A. 10%
• B. 50%
• C. 80%
• D. 100%

Answer: (B)

The main idea here is how common Salmonella enteritidis is on pig farms. Pigs can carry this organism without showing illness, and the bacteria can persist in the farm environment and on surfaces, so many farms end up testing positive over time.

The best answer reflects what surveillance data tend to show: a substantial portion of pig farms harbor the organism, roughly around half. This acknowledges that Salmonella enteritidis is widespread enough to be a regular concern in swine settings, but not so universally present that every farm tests positive. It also aligns with the reality that some farms effectively control or intermittently test negative, while others may carry it due to ongoing exposure in the production environment.

A very small minority of farms testing positive would understate how commonly the bacterium is found in swine operations. On the other hand, the notion that nearly all farms test positive or that every farm is positive is not consistent with typical surveillance results and the positive impact of biosecurity and control measures.