ByHeart, which makes organic infant formula, recalled all of its products sold throughout the U.S. on Tuesday amid a growing outbreak of infant botulism.

At least 15 babies in 12 states have been sickened in the outbreak tied to ByHeart formula, state and federal health officials said. That's an increase from 13 cases in 10 states reported Saturday.

No deaths have been reported in the outbreak, which began in August.

ByHeart officials said parents and caregivers who have the formula in their homes “should immediately discontinue use and dispose of the product.”

The outbreak has sickened babies age 2 weeks to 5 months since it started. The infants were hospitalized after consuming ByHeart powdered formula, according to the U.S. Centers for Disease Control and Prevention.

California officials confirmed that a sample from an open can of ByHeart baby formula fed to an infant who fell ill contained the type of bacteria that causes the toxin linked to the outbreak.

ByHeart officials said they recalled their products “in close collaboration” with the U.S. Food and Drug Administration, despite the fact that no previously unopened product tested positive for the illness-causing bacteria. The type of bacteria that produces the toxin is widespread in the environment and could come from sources other than the formula, company officials said.

The FDA is investigating 84 cases of infant botulism detected since August. Of those, 15 consumed ByHeart formula, the agency said in a statement.

Illnesses began between Aug. 9 and Nov. 10, federal officials said. Cases were reported in Arizona, California, Illinois, Kentucky, Minnesota, North Carolina, New Jersey, Oregon, Pennsylvania, Rhode Island, Texas and Washington.

Investigators have not identified any other infant formula brands or other sources of exposure in the outbreak, officials said.

Infant botulism typically affects fewer than 200 babies in the U.S. each year. It is caused by a type of bacteria that produces a toxin in the large intestine. The bacterium is spread through hardy spores present in the environment that can cause serious illness, including paralysis.

Infants are particularly vulnerable to infection because their gut microbiomes are not developed enough to prevent the spores from germinating and producing the toxin. They can be sickened after exposure to the spores in dust, dirt or water or by eating contaminated honey.

Symptoms can take weeks to develop and can include poor feeding, loss of head control, drooping eyelids and a flat facial expression. Babies may feel “floppy” and can have problems swallowing or breathing.

No known outbreaks of infant botulism tied to powdered formula have previously been confirmed, said Dr. Steven Abrams, a University of Texas nutrition expert.

The only treatment is known as BabyBIG, an IV medication made from the pooled blood plasma of adults immunized against botulism. California's Infant Botulism Treatment and Prevention Program developed the product and is the sole source worldwide.

BabyBIG works to shorten hospital stays and decrease the severity of illness in babies with botulism. Because the infection can affect the ability to breathe, infants often need to be placed on ventilators.

All of the children in the ByHeart outbreak have received the medication, the CDC said. The treatment is delivered in vials that cost $69,300 apiece, Pan said.

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