After a deadly listeria outbreak tied to deli meat this summer, consumers in Maryland and nationally again are being warned about the bacteria — this time in mushrooms.

A Maryland Department of Health on Thursday warned consumers not to eat enoki mushrooms produced by Enoki King Mushroom Farm in Ventura, California, because of potential contamination.

The department tested samples in early October and found listeria. State officials are now working with the U.S. Food and Drug Administration and other states to investigate the source of the bacteria, which can be found in dirt and sewage and elsewhere in the environment where crops are grown.

Maryland health officials were integral in uncovering the culprit behind the summer listeria outbreak, triggering a nationwide recall of more than 7 million pounds of deli meats from a plant in Virginia.

Maryland also had a listeria outbreak in an Owings Mills ice cream factory in September.

Maryland typically confirms about two dozen cases of listeria a year, but other foodborne illnesses are more common, such as salmonella and campylobacter.

Nationally, an estimated 48 million Americans are sickened by food a year, 128,000 are hospitalized and 3,000 die, according to the U.S. Centers for Disease Control and Prevention.

As for the mushrooms, they have been recalled. They come in a 5.3-ounce clear plastic package with a blue label, with lot code 4877 on the front and UPC code 860011505600 on the back.

The U.S. Food and Drug Administration says there have been no reports of illness so far.

But officials say if you’ve eaten the mushrooms, be on the lookout for symptoms including fever and muscle aches, diarrhea, vomiting and cramps. An infection can lead to bloodstream infections and meningitis, which is inflammation in the brain or spinal cord. It’s treated with antibiotics.

Such infections can be especially harmful to pregnant women and their newborns, older adults and people with weakened immune systems.

A particularly important note: People can be sickened up to two months after eating contaminated food, possibly complicating an investigation into the source of the illness.

Generally, health officials say consumers should store enoki mushrooms separately from other foods and cook the mushrooms before eating them. If they contain listeria, however, heat will not kill the bacteria.