The Centers for Disease Control and Prevention has linked the contaminated cheese to Roos Food of Kenton, Delaware.
The outbreak is linked to semi-soft, Latino-style cheese called cuajada en terron or fresh cheese curd that is sold from a chain of grocery stores in Maryland.
The grocery chain linked to the outbreak was not named, but the cheese was sold under brand names Santa Rosa de Lima, Amigo, Mexicana, Suyapa, La Chapina, and La Purisima Crema Nica.
Listeria is a serious illness that includes fever and muscle aches, often with other gastrointestinal symptoms.
The illnesses were diagnosed between August and November of last year, but the CDC said there may be more.
The Associated Press contributed to this report.
