The Marine Corps says 69 recruits in Southern California are being treated for apparent exposure to E. coli and nine have developed a serious complication, according to the Associated Press.
Those being treated include 14 new cases among some 5,500 recruits at Camp Pendleton and the San Diego recruiting depot.
The military says nine developed hemolytic uremic syndrome, a problem that can cause anemia and kidney damage.
Overall, about 300 Marines have been affected by a week-old outbreak of the diarrheal illness.
The source of the outbreak is under investigation.
Training continues and some 500 Marines graduated from training on Friday.
The Marine Corps says efforts will be made to allow recruits who had to miss training to make it up.
The Associated Press contributed to this report.