One death has been reported in a U.S. outbreak of salmonella infections that U.S. officials say were likely caused by eating ground turkey.

The U.S. Centers for Disease Control and Prevention said a total of 77 persons infected with the outbreak strain of Salmonella Heidelberg have been reported from 26 states between March 1 and August 1.

"The outbreak strain of Salmonella Heidelberg is resistant to many commonly prescribed antibiotics; this antibiotic resistance can increase the risk of hospitalization or possible treatment failure in infected individuals," the agency said. U.S. health officials aren't advising consumers to avoid eating ground turkey, but to cook it properly. Larry Crowe/AP

Cultures of ground turkey from four retail locations between March 7 and June 27 showed salmonella contamination. The agency said preliminary information showed that three of the samples have been linked to the same production establishment but the retailers or manufacturers were not named.

The U.S. Department of Agriculture is responsible for issuing recalls for meat safety.

Late last week, the USDA sent out an alert telling people to properly cook turkey to reduce the risk of foodborne illness from salmonella. No further warnings have been given.

USDA's Food Safety and Inspection Service "has not linked these illnesses to a particular brand, product, or establishment, and therefore has not issued a recall," spokesman Brian Mabry said Tuesday. "We are continuing to investigate this situation."

The CDC said it and the USDA were "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."

'Consumers have no idea what to do except not eat ground turkey.'— Bill Marler

Food safety advocate Bill Marler, an attorney who has represented victims of the biggest food-borne illness outbreaks in the U.S., said he believes the three positive samples should prompt a recall.

Time to confirm cases

"Consumers have no idea what to do except not eat ground turkey," he said.

Uncertainty about the outbreak's source might explain the silence, said University of Pennsylvania bioethicist Art Caplan, who added, "the moral duty is to really get the word out as soon as you have evidence of a problem."

CDC spokeswoman Lola Russell said it can take three to four weeks to confirm one case. Identifying an outbreak can take considerably longer than that when cases of foodborne illness occur sporadically, in several states, as has happened in the current outbreak, Russell said.

The states with the highest number sickened were Michigan and Ohio, 10 illnesses each, while nine illnesses were reported in Texas. Illinois had seven, California six and Pennsylvania five.

The remaining states have between one and three reported illnesses linked to the outbreak, according to the CDC: Alabama, Arizona, Georgia, Iowa, Indiana, Kentucky, Louisiana, Massachusetts, Minnesota, Missouri, Mississippi, North Carolina, Nebraska, Nevada, Oklahoma, Oregon, South Dakota, Tennessee and Wisconsin.

Russell said the CDC isn't advising the public to avoid eating ground turkey, but does urge people to cook it properly.

The Canadian Food Inspection Agency advises consumers to cook ground poultry to 74 C or 165 F.

Most people infected with salmonella develop diarrhea, fever and abdominal cramps six to 72 hours after being infected, Health Canada says. Commons symptoms of salmonella include diarrhea, fever, cramps, nausea, headache and vomiting that last for four to seven days.

People usually recover without treatment but it can be life-threatening, particularly for those with weakened immune systems.

About 6,000 to 12,000 cases of salmonella are reported in Canada each year, according to Health Canada's website. Many milder cases are not diagnosed or reported.

With files from The Associated Press