Undercooked chicken served at the Suffolk jail in Riverhead led to a salmonella outbreak that sickened at least 21 inmates in May, health officials said.

One inmate who was hospitalized has filed a notice of claim with the county, a prelude to a lawsuit.

“Suffolk County has an affirmative obligation to provide its prisoners in jail all food that is free from any deleterious or harmful substance,” said Andrew Siben a Bay Shore attorney representing the inmate, Shawn Carpenter.

Carpenter, 39, of North Babylon, became ill on about May 20 while being held in the jail, Siben said.

Siben claims the county was negligent in the “ownership, operation, control, management and supervision” of the jail “kitchen and food preparation areas, mess room and infirmary.”

Jail officials and County Attorney Dennis Brown could not be reached for comment Thursday.

Vanessa Baird-Streeter, a county spokeswoman, declined to comment, citing the county’s policy on pending litigation.

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The notice claims Carpenter, who was in the jail on a parole violation, suffered gastrointestinal woes consisting of “personal bodily injuries, including but not limited to Salmonella enterocolitis, pancreatitis and thrombocytosis.”

Carpenter was treated at Peconic Bay Medical Center in Riverhead and is now back in jail, Siben said.

County health officials confirmed that a salmonella outbreak occurred around the time Carpenter was hospitalized, and that experts were sent in to contain it.

“We believe the onset was May 10 and went on for a week and a half,” said Health Department spokeswoman Grace Kelly-McGovern. “We sent out our infectious disease experts, including epidemiologists and public health ... inspectors.”

The officials collected samples and after ruling out norovirus concluded that the culprit was salmonella from undercooked chicken.

Kelly-McGovern said the poultry was delivered frozen and likely deteriorated in either its storage or preparation.

Most people infected with salmonella develop abdominal cramps, fever and diarrhea 12 to 72 hours after being exposed to the bacteria, according to the U.S. Centers for Disease Control and Prevention. The illness typically lasts 4 to 7 days, and most people recover without treatment.

Suffolk health officials distributed to inmates and jail officials a flyer outlining tips that could help prevent another outbreak, including washing hands, eating meals when they are served and reporting illnesses promptly to prevent the spread of disease.