Salmonella outbreak sickens over 70 people. Here’s how to protect yourself.

The Food and Drug Administration earlier this week reported a widespread outbreak of salmonella food poisoning that sickened 73 people in 22 states, resulting in 15 hospitalizations. The cases have been linked to tainted bagged diced onions and celery made by the California company Gills Onions.

Salmonella is the most frequently reported cause of foodborne illness, according to the Department of Agriculture. It results in 1.35 million infections, 26,500 hospitalizations and 420 deaths annually in the United States — almost all of them from contaminated food — according to the Centers for Disease Control and Prevention.

What is salmonella? How can you prevent becoming ill from it? The Washington Post asked several experts, and here’s what they said.