Avian flu outbreak raises a disturbing question: Is our food system built on poop?

In the 1980s, concerns about bovine spongiform encephalopathy — or mad cow disease — took hold across Europe, when cases of the incurable and invariably fatal neurodegenerative disease of cattle began to appear. The disease, which is caused by folded proteins known as prions, can transfer to people who eat the meat of infected cattle. In people, the disease is fatal and called Creutzfeldt-Jakob disease.

Just as cattle are fed poultry waste, chickens are often provided feeds that consist of cattle waste and renderings — creating a potential route for prions to re-enter the food supply. However, because the FDA mandates the removal of all tissues shown to carry the prions — such as brains and spinal cords — from poultry diets, the risk is reduced.

However, other more common pathogens are also found in poultry litter. In one 2019 study of litter used on farm fields as fertilizer, researchers found that every sample tested from U.S. broiler chickens carried E. coli strains resistant to more than seven antibiotics — including amoxicillin, ceftiofur, tetracycline, and sulfonamide.

It is unclear if the litter was heat treated before it was applied.

Raudabaugh said all poultry litter feed in California is kiln heated and exposed to temperatures that can kill bacteria, such as E. coli, and viruses, including H5N1.

“Firms are sampling and analyzing finished product for Salmonella regularly,” said Lyle, the state’s food and agriculture spokesman.

He noted that poultry is regularly tested for bird flu and that poultry waste from a flock infected with bird flu “cannot leave the premises until it has met CDFA requirements for ensuring the virus has been eliminated,” he said. “The premises is also tested and the quarantine is not released until the premises tests negative for highly pathogenic avian influenza.”

Lyle said cattle herds with “symptoms consistent” with bird flu infections “can be tested at the California Animal Health and Food Safety Laboratory in consultation with the CDFA Animal Health Branch.”

He added that no symptomatic herds have been identified, “although one herd that lost pregnancies was tested and was negative” for the virus.