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ARVADA, Colo. — At least four people in a Colorado family have come down with salmonella after a nationwide recall of pistachios.

Wonderful brand pistachios initiated a voluntary recall of some of its products on March 9 because of a possible link to salmonella cases in nine states.

The Centers for Disease Control and Prevention traced the outbreak back to Paramount Farms in Lost Hills, Calif. As of March 7, 11 people had fallen ill with salmonella. The pistachios were sold under the brands Wonderful, Traders Joe’s and Paramount Farms.

On Friday, four people in one Colorado family also tested positive. The CDC warns more cases linked to the contaminated pistachios could increase in the next few weeks as people consume the nuts.

“I don’t know if you’ve ever had food poisoning, but it’s painful and this was about 10 times worse,” Mike Larsen said.

Larsen ended up in the hospital where doctors confirmed he had the foodborne bacteria. Larsen, his girlfriend and his parents got sick after sharing a bag of Wonderful pistachios his parents bought at Walgreens in Arvada about a month ago.

The bag was recalled by the company, but the Larsens said they were unaware there was a pistachio recall.

“It’s not something you research and it’s not something you look into, but maybe something that we want to glance at once a month now,” he said.

Salmonella causes painful abdominal cramps, diarrhea, vomiting and fever, and can be deadly in children, seniors and those with a weakened immune system.

The recalled bags can be identified using a 13-digit lot code number on the back or bottom of the packaging.