Two companies processed and supplied dried milk powder that could be a culprit in the outbreak of botulism tied to ByHeart infant formula that has sickened dozens of babies, The Associated Press has learned.
Organic whole milk powder that tested positive for the type of bacteria that causes botulism was made from milk provided by Organic West Milk Inc., a California company, and processed at a Dairy Farmers of America plant in Fallon, Nevada, company officials said.
Related: Oregon Baby Still Battling Botulism After ByHeart Formula Exposure
The source of the contamination, however, is not yet known. Both companies and the U.S. Food and Drug Administration emphasized that the investigation into the unprecedented outbreak that has sickened 51 babies in 19 states is ongoing.
Bill Van Ryn, an owner of Organic West Milk, said he learned last week that a sample of his company’s milk powder collected by the FDA had tested positive for the germ that causes botulism.
But that doesn’t mean his product is the source of the outbreak, Van Ryn stressed.
Related: Target, Walmart, Whole Foods Targeted in Botulism Suits
“Nothing has been proven about our milk yet,” he said, adding: “Something happened in the process of converting the milk to powder and then in converting it to baby formula.”
Organic West, which supplies milk from 55 farmers, didn’t sell organic whole milk powder to any infant formula maker besides ByHeart, Van Ryn said. The milk company has halted sales of the powder used in any product intended for babies and children until more is known about the source of the outbreak, he added.
Powdered milk is made by pasteurizing liquid milk, concentrating it through evaporation and spraying it into a hot chamber, which causes the water to evaporate and leave behind fine, dry milk particles.
The Dairy Farmers of America is a global dairy cooperative. Its plant in Nevada processes about 1.5 million pounds of raw milk daily into 250,000 pounds of whole milk powder.
The Dairy Farmers of America said in a statement that Organic West was the source of milk for the sample that FDA collected that tested positive for botulism bacteria. The milk was processed into powder that met all required tests, the company said. Organic West subsequently sold the milk powder to ByHeart.
“Manufacturers of end-use consumer products have a responsibility to properly process ingredients to ensure product safety,” the statement read.
FDA officials said on Jan. 23 that a sample of organic whole milk powder collected from a supplier had tested positive for the botulism bacteria, though the agency didn’t identify the supplier. Tests showed that sample was a genetic match to a sample taken from a finished can of ByHeart formula.
The agency also found the bacteria in an unopened can of formula matched a sample from a sick baby — and it also matched contamination detected in samples of milk powder used to make ByHeart formula and collected and tested by the company.
ByHeart officials declined to identify the source of those milk powder samples. The infant formula company has recalled all its products.
Botulism spores are common in the environment and can be found in most foods at very low levels, said Kristin Schill, a botulism expert at the University of Wisconsin-Madison.
Healthy adults consume Clostridium botulinum spores every day without becoming sick. But babies have immature guts that may not be able to prevent the spores from germinating and growing. Once they do, the spores produce a toxin that can cause paralysis and death.
Spores can be found everywhere, including in milk, though typically at low levels, Schill said. Pasteurization doesn’t kill the germs. They can be present in the processing environment, too.
Botulism spores have been found in infant formula in the past, but this is the first large outbreak linked to the product. The risk has been considered so low that testing for botulism in infant formula is not required, though some formula makers voluntarily screen for microbiological signals that could indicate contamination.
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.
Copyright 2026 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
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