(Jennifer Domenick/THE WASHINGTON POST)

Twenty-two people in seven states have been infected with a strain of Listeria, according to the CDC. Four deaths have been reported, according to the Associated Press, while the CDC says only two deaths have been linked to the outbreak.

Listeriosis is an infection that can cause fever and muscle aches as well as gastrointestinal issues, according to the CDC. It particularly affects the elderly, pregnant women and people with weak immune systems. In severe cases, it can also cause confusion and convulsions.

The FDA announced Wednesday that Colorado-based Jensen Farms had recalled its Rocky Ford cantaloupes, which are believed to be the source of the contamination. A spokesperson for the farm told the AP that one of its cantaloupes had tested positive for Listeria. But further tests are needed to determine whether it’s the same strain from the outbreak.

Already, a Colorado couple is planning to sue the company and the place where they bought the cantaloupe, ABC 7 News Denver reported. A lawyer for Charles Palmer said he ate a cantaloupe purchased at Wal-Mart and was hospitalized shortly after with the infection.