Two more cases have been added to the multistate outbreak of listeriosis linked to imported Frescolina Marte brand ricotta salata cheese, according to the Centers for Disease Control and Prevention. As of Friday, CDC said a total of 22 persons infected with the outbreak-associated strain of Listeria monocytogenes have been reported from 13 states and the District of Columbia. Of the known cases, 20 people were hospitalized. Four deaths have been reported. Listeriosis contributed to at least 2 of these deaths, according to the CDC’s update. The agency also said that one fetal loss has been reported. Health officials investigating at the local, state, and federal level have found that imported ricotta salata cheese is the likely source of the outbreak. CDC is reminding consumers to be on the look out for the products: “Cheese retailers should not sell or serve recalled Frescolina Marte brand ricotta salata cheese distributed by Forever Cheese, Inc., regardless of any expiration coding.” The recalled cheese should be off store shelves now — the recall began on Sept. 10 and was expanded on Sept. 14., but CDC said that more ill persons may be reported because up to 2 months can elapse between eating contaminated food and developing listeriosis.