U.S. disease and food safety agencies have sent out a warning of a new Listeria outbreak occurring in several states. The agencies said that they are investigating the outbreak, which could be tied to "Hispanic-style cheeses" such as white cheese or queso fresco.

The Centers for Disease Control (CDA) and Food Drug  Administration (FDA) have yet to determine the exact source of the bacterial infections but the agencies are investigating several food items. This covers several kinds of cheese such as queso blanco and queso fresco.

The CDC said that at least seven people had been admitted to hospitals with Listeria symptoms. The patients were identified to be consumers from Maryland, New York, Connecticut and Virginia.

Listeria is caused by a food-borne bacterium that can be very dangerous for people older than 65 years old, pregnant women, and those with compromised immune systems. The illness is mainly caused by improperly processed meats and unpasteurized milk products.

Listeria symptoms include muscle aches, and gastrointestinal problems. If the infection spreads to the nervous system, it may cause confusion, loss of balance, headaches and convulsions.

The FDA said that consumers should make sure that the cheeses they buy are made with pasteurized milk. One way to do this is by properly reading the label and packaging, the agency said. The FDA warned that while Pasteurization may kill the bacteria, unsanitary conditions in the handling of the food could still result in contamination.

As part of its latest warning, the FDA is advising immune-compromised individuals to avoid eating Hispanic-style fresh and soft cheeses while they are still trying to pinpoint the exact product responsible for the outbreak.

The FDA said that Maryland had reported the greatest number of hospitalizations, with four out of the seven recorded infections. The agency said that more people could have been infected but Listeria does go away on its own in healthier individuals.

Listeria symptoms often last up to five days. Most people will not need any medication, but it will depend on the severity of the symptoms. People with more-serious infections can opt to use antibiotics to get rid of the disease.