A salmonella outbreak first identified by the Centers for Disease Control and Prevention (CDC) in early September has been growing rapidly. As of last Thursday, reported U.S. cases totaled 279 — more than double reported the week before. The illness has spread to at least 29 states and resulted in 26 hospitalizations.

Those who have fallen ill range in age from younger than 1 year to 89 years, with a median age of 35. About 6 in 10 are female.

Although federal health investigators have not identified the source of this bacterial disease, recent testing found the outbreak strain of Salmonella Oranienburg in a sample taken from a takeout condiment cup containing cilantro and lime.

“The sick person reported that the condiment container also contained onions, but none were left in the cup when it was tested,” wrote the CDC. “Because multiple food items were present in the container and in the sample that was tested, it is not possible to know which food item was contaminated. We are using this information in conjunction with other available information to help narrow the list of possible foods linked to illness.”