BOSTON -- Three additional cases of salmonella in the Bay State have been linked to the nationwide outbreak linked to certain varieties of raw tomatoes, according to the Massachusetts Department of Public Health.

The new cases bring the total number of cases identified in Massachusetts to 24. Five of those cases involved patients who had to be hospitalized, state officials said. All of the reported cases became ill between late May through mid-June.

Federal health officials continue to investigate the source of the contamination, however, until a source is identified, consumers are urged to avoid certain types of tomatoes. The investigation has linked tomatoes to the outbreak, but many clusters of illnesses have been identified in people who ate at restaurants.

These clusters have led officials to widen their investigation to include food items commonly eaten with tomatoes -- raw tomatoes are often found in fresh salsa, guacamole and pico de gallo and are used in many other dishes.

While health officials have expanded the number of food items under investigation, the FDA and CDC have only issued consumer advisories regarding the consumption of tomatoes.

Since the outbreak began, the FDA has advised consumers to avoid certain raw red plum, raw red Roma, raw red round tomatoes and products containing these tomatoes. Tomatoes that are safe to eat include cherry, grape, tomatoes sold with the vine still attached and tomatoes grown at home. These are not likely to be tainted by salmonella.

Tomatoes grown in Massachusetts are considered safe to eat by the FDA.

The cases were identified through on-going surveillance involving DNA matching of the outbreak strain with samples submitted by health care laboratories throughout Massachusetts. The strain of salmonella identified is Salmonella Saintpaul, a specific sub-type of the bacteria.

To date, almost 1,000 cases linked to certain tomatoes have been reported nationwide, according to the CDC. Health officials in 40 states, including Maine, New Hampshire, Vermont, Rhode Island, Connecticut and New York have also identified cases.