Federal investigators have confirmed 76 patients across 16 states as of Oct. 1 in a dual-pathogen outbreak of E. coli and Salmonella traced to alfalfa sprouts from Everything Sprouts LLC of Minneapolis, the Food and Drug Administration reported. Six people have been hospitalized. No one has died.

That count is up from 55 patients when the FDA first announced the outbreak on Aug. 21. Illness onset dates run from May 31 to Sept. 7, a window of more than three months, and the case count will almost certainly keep rising.

The outbreak is unusual on two fronts: it involves two distinct pathogens, and some patients were infected with more than one outbreak strain. The confirmed breakdown:

• 64 people infected with E. coli — multiple serotypes, including O26:H11, O103:H25 and O168:H8
• 9 people infected with Salmonella Agona
• 3 people infected with both Salmonella and E. coli

How strong is the evidence against the sprouts?

State and local public health officials have interviewed patients about foods eaten in the week before illness. Of 50 people interviewed so far, 40 reported eating sprouts, and 35 specified alfalfa sprouts — a 70 percent exposure rate among those questioned.

Epidemiologic and traceback evidence ties alfalfa sprouts grown by Everything Sprouts LLC to the illnesses. But the FDA was explicit about the limits of that finding: the Minneapolis grower's sprouts do not explain all the illnesses. That gap points investigators upstream, toward the seed supply.

On Aug. 22, one day after the FDA's first announcement, Everything Sprouts LLC recalled certain alfalfa sprouts sold under the Calco and Everything Sprouts brands. The company also pulled three additional mixes: Robust Radish, Crunchy Protein Sprout and Zesty Garlic.

What triggered the second recall?

On Sept. 23, Berlin Seeds of Millersburg, Ohio, recalled 950 pounds of alfalfa sprouting seeds after its seed supplier notified the company that the seed could be contaminated with STEC and/or Salmonella. Seed lot SAL2-24JB had been identified through traceback as seed used by another sprout grower whose finished sprouts were part of the FDA's outbreak investigation.

The FDA is not naming the seed supplier.

The 16 states with confirmed patients span both coasts and the Midwest: Florida, Indiana, Iowa, Kansas, Michigan, Minnesota, New Hampshire, New York, North Carolina, North Dakota, Oregon, Pennsylvania, South Carolina, South Dakota, Washington and Wisconsin.

Why the real case count is likely far higher

The FDA cautions that many more people are likely sick than the official count reflects. Some infected people never seek medical treatment; others are not tested for pathogens. CDC multipliers quantify the gap:

• For every confirmed Salmonella patient, an estimated 29 cases go undetected
• For every confirmed E. coli patient, an estimated 26 cases go undetected

Applied to this outbreak, those multipliers suggest the true number of infections could reach into the thousands.

What operators should watch

For restaurants and foodservice buyers, the outbreak is a reminder of sprouts' persistent food-safety profile. Contaminated seed is the recognized root cause in most sprout outbreaks, and growing conditions — warm, moist, dark — amplify any pathogen present on the seed. Buyers sourcing sprouts should verify grower testing protocols and seed lot documentation, particularly for product passing through regional distributors.

Symptoms of E. coli infection include severe stomach cramps and diarrhea, often bloody, with some patients developing fever. Most recover in five to seven days, but 5 to 10 percent of diagnosed patients develop hemolytic uremic syndrome, a potentially life-threatening kidney failure complication most common in children under five, older adults and immunocompromised individuals. Salmonella symptoms — diarrhea, abdominal cramps and fever — typically appear 12 to 72 hours after exposure, and healthy adults are usually sick for four to seven days.

Anyone who ate the implicated products and developed symptoms should seek medical attention and tell their doctor about the possible exposure, since both infections require specific tests to diagnose and frequently mimic other illnesses.

The FDA's investigation remains active, and the patient count is expected to grow as more interviews and lab results come in.