The recall of organic baby formula is expanding. It's linked to an outbreak of botulism among babies. Botulism is a rare but life-threatening illness that can make it difficult for an infant to breathe.

Infant formula maker ByHeart expanded its voluntary recall and is taking all of its baby formula off the shelves. At least 15 babies were hospitalized in 12 states with infant botulism after consuming ByHeart formula. Two of the 15 cases are reported in Texas. Those babies were treated with antibodies. No deaths have been reported.

Incubation period raises concern for parents 

"The incubation period can be up to seven weeks. Kids that consumed the product a week ago may not show signs or symptoms for another month and a half. Obviously, that's super concerning to parents," food safety lawyer Bill Marler said.

Dr. Carla Garcia Carreno, infection prevention director with Children's Health Plano, said some of the early symptoms of botulism can include poor feeding, such as difficulty sucking or swallowing, and loss of head control.

Symptoms progress from head downward 

"Essentially, there is a blockage of the transmission from the nerves to the muscle, so these babies get floppy. It's really characteristic that things are going to come from the head down," Carreno said.

Carreno encourages parents to call 911 if the baby struggles to take in air.

"If things are progressing, and the baby is floppy and has some difficulty breathing, because the diaphragm or the muscle that helps us breathe can be weak as well, don't wait for the pediatrician evaluation," Carreno said. "Go to the ER. Call 911."

Steps parents can take at home 

Parents can take steps to reduce the risk and protect their infants.

"Don't feed honey to babies less than a year old because that's usually the traditional product that has been linked to more of a risk for having the spores of the Clostridium botulinum," Carreno said. "Families need to wash hands very thoroughly before preparing the feeds of the baby."

FDA confirms pathogen in ByHeart formula 

The FDA is investigating the cases and inspected the ByHeart facility this week.

"We did test one of the bottles from this company and did confirm that there in in fact was a botulism pathogen," FDA Commissioner Dr. Marty Makary said.

Experts said botulism is particularly dangerous for babies because their bodies can't easily fight off the toxin.

Cases spike far above yearly average 

Eighty-four infant botulism cases have been reported in the last three months nationwide. Typically, about 100 cases are reported during an entire year.