Roughly 26 states reported the illness of Salmonella poisoning linked to ground turkey between March 1 and August 1, with Michigan, Ohio, Texas, Illinois, California and Pennsylvania reporting the most cases, the Centers for Disease Control and Prevention said Tuesday.

Public health officials were still looking for the source of the contamination, but preliminary information suggested that a single production facility may be involved. Salmonella infection is a major public health problem worldwide, health officials said. There are an estimated 1.7 million infections in North America each year and more than 1.6 million cases were reported between 1999 and 2008 in 27 European countries.

"There is little epidemiological information available at this time that conclusively links these illnesses to any specific product or establishment," FSIS spokesman Neil Gaffney, told CBS News. "Without specific enough data, it would not be appropriate to issue a recall notice."

The CDC reported that the highest number of cases have been found in Michigan, Ohio, Texas, Illinois, California and Pennsylvania. The agency reported that cases have also been found in Alabama, Arizona, Georgia, Iowa, Indiana, Kentucky, Louisiana, Massachusetts, Minnesota, Missouri, Mississippi, North Carolina, Nebraska, Nevada, Oklahoma, Oregon, South Dakota, Tennessee and Wisconsin.

Researchers examined the cases in North America and said reports of infection in Canada and contamination of imported foods in the United States suggest the new strain - called S. Kentucky - has also reached there.

For more details on the 77 cases, see the CDC's Salmonella Outbreak Investigations: Timeline for Reporting Cases.

CDC officials said it can take three to four weeks to confirm a single case and identifying an outbreak can take considerably longer than that. Also, that individuals should wash their hands, kitchen work surfaces, and utensils with soap and water immediately after they have been in contact with raw meat or poultry including frozen, fresh ground turkey.

Health officials add that raw poultry should be cooked thoroughly to 165 °F internal temperature as measured with a food thermometer; leftovers should also be reheated to 165 °F.

Of the cases counted by the CDC, there are 58 confirmed cases; the oldest person affected was 88 and the youngest was under one year old, with the median age of 23. On July 29, USDA-FSIS released a public health alert for frozen or fresh ground turkey products, according to the agency.

On Tuesday, the Associated Press reported that the CDC and the U.S. Department of Agriculture said both agencies are "vigorously working to identify the specific contaminated product or products that are causing illnesses and will update the public on the progress of this investigation as information becomes available."

Among the 51 ill persons with available information, 25 of those, or 49 percent, reported consuming ground turkey. Cultures of four ground turkey samples purchased from four retail locations between March 7 and June 27, 2011 yielded Salmonella Heidelberg with the outbreak strain, CDC officials add.