Salmonella cases across 17 states have been linked to nearly 1.6 million recalled cartons of eggs.
The Hill reported that federal investigators say other sources may also be contributing to the outbreak.
The eggs, produced in Texas, were sold at Kroger stores in Texas and Louisiana and at Brookshire Grocery stores in Texas, Oklahoma, Arkansas, Louisiana, New Mexico, and Mississippi, along with food service and retail customers in Texas, Oklahoma, and Louisiana.
The Centers for Disease Control and Prevention and the Food and Drug Administration have linked an ongoing outbreak to the recalled eggs, though cases have appeared in states far from where the eggs were distributed, including Michigan and New York.
Texas has reported the most cases.
The CDC has recorded 98 illnesses linked to the outbreak, though the true number is likely higher since some people recover without seeking medical care or testing.
At least 26 of those who became ill required hospitalization. Ages of those sickened range from under a year old to 81. At least one illness was reported in late November, with the most recent case reported June 30. No deaths have been linked to the outbreak.
The FDA said the recalled eggs were "identified as a common egg source" among those who fell ill but that the producer "does not account for all the illnesses in this outbreak," adding that "additional investigation is ongoing to determine if there are other sources of illness."
The recall was announced Wednesday by Midwest Poultry Services, covering 1,589,577 dozen white and brown cage-free eggs produced at two Texas farms between June 6 and July 3.
The company said it identified the issue through routine environmental monitoring, not through illness reports, and that no illnesses had been linked to the eggs at the time of the recall announcement.
Buyers should check cartons for sell-by or best-by dates between July 20 and Aug. 17, along with plant code P-1950 or 840962.
Salmonella causes roughly 1.35 million illnesses and 420 deaths in the U.S. each year, according to the CDC.
Symptoms include diarrhea, fever, and stomach cramps, appearing six hours to six days after exposure. Most people recover within four to seven days without treatment.