ATLANTA — Public health officials have linked an outbreak of illnesses in the state caused by cyclospora to fresh cilantro harvested in Puebla, Mexico. The C.D.C. indicated the cyclospora outbreak that has sickened 643 people from 25 states may be multiple outbreaks from different sources.

Officials in Iowa and Nebraska concluded that the cyclospora illnesses in those two states came from salad mix produced by a business unit of Taylor Farms that is based in Mexico.

A C.D.C. epidemiologic study among persons who reported eating at a single Mexican-style restaurant in Fort Bend County, Texas, compared foods eaten at the restaurant by 25 ill persons and 65 healthy persons. Ingredient-level analyses were conducted using meal consumption data and recipes. Four fresh produce ingredients were associated with illness: cilantro, whole onions, garlic and tomatoes. Since these ingredients were served together in many different dishes, such as salsa, the C.D.C. said statistical analysis could not definitively identify which of the ingredients was independently associated with illness.

Fresh cilantro was the only ingredient consumed by all 25 ill persons in the study. Consumption of lettuce was not associated with illness in the analysis, and trace-back information indicated that lettuce served in the restaurant was not from any business associated with Taylor Farms.

Preliminary trace-back information indicated fresh cilantro harvested from the Puebla, Mexico area, was supplied to restaurants and a grocery store in Texas during the period when people became ill. The Food and Drug Administration said it is working with Mexican authorities to determine if there is a common farm or growing area in Puebla, Mexico, which may have provided the fresh cilantro.