The Mad Cow Disease dilemma in Great Britain provides a good example of how a system change can unintentionally make things worse.

The public's perception about the risk of illness due to beef consumption caused people to eat less beef and eat more chicken.

However, the risk of contracting mad cow disease was actually low compared to the risk of becoming ill due to eating salmonella-contaminated chicken.

The resulting shift in dietary patterns resulted in an increase in death rates caused by salmonella.