John Boelts, first vice president of the Arizona Farm Bureau, has a quick and dirty science lesson for you.

Boelts is a farmer himself, with over 20 years experience in Yuma farm fields growing everything from fresh produce to wheat. He said, first of all, the romaine lettuce that sickened people in 22 states this month is no longer on market shelves.

When an E. Coli outbreak happens, he said, much of the investigative work falls on the Centers for Disease Control and Prevention and U.S. Food and Drug Administration to figure out what the common element is between sick people scattered across the country. They work backwards to find how and where the foodstuff was handled.

Boelts said the most important thing to farmers is that people who have fallen ill get the best medical care they can. Their second priority, he adds, is to learn what happened and apply best industry practices to make sure it doesn’t happen again.

In the end, though, sometimes federal authorities can’t find a specific reason why e.coli broke out. One wild animal walking through a field pre-harvest can ruin an entire field, preventing it from being harvested, for example. But if history is any guide, an outbreak like this can have devastating economic consequences.