Foodborne Illness Outbreak Database

This database provides summaries of significant food and water related outbreaks occurring since 1984 caused by E. coli, Salmonella, Hepatitis A, Campylobacter and other pathogens. Read more »

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1998 Outbreak of Salmonella Senftenberg and E. coli O157:NM Associated with Alfalfa-Clover Mixed Sprouts

A northern California sprout grower was implicated in a prolonged outbreak involving its alfalfa-clover mixed sprouts. The outbreak began with the identification of a cluster of Salmonella Senftenberg cases; the case control study showed that the consumption of mixed alfalfa-clover sprouts was associated with risk of illness. During the initial investigation, no Salmonella was isolated from the sprouts or the seeds. The sprout grower disinfected seeds irregularly. The sprouter was advised to stop using the seeds, however the sprouter did not heed that advice. Between January and May, 1998, one to three additional Salmonella Seftenberg cases were identified and then in June and July, 1998, twenty more were reported prompting additional investigation. In addition, eight cases of E. coli O157:NM were reported in June, 1998, and were epidemiologically linked to eating the same sprouts. This time the outbreak strain of Salmonella Seftenberg was isolated from alfalfa-clover sprouts, however no E. coli O157:NM was ever isolated from the sprouts. Several related lots of clover seed but no specific lot (or related lots) of alfalfa seed could explain this outbreak. The source of the clover seeds was a distributor who obtained seeds from farms in Oregon. Ultimately 60 Salmonella Senftenberg cases and eight E. coli O157:NM were identified.

  • Outbreak began:
  • September 1997
  • Affected Country:
  • US
  • Affected States/Territories:
  • California
  • Organism(s):
  • Salmonella
    Non-E.coli O157:H7
  • Vehicle(s):
  • Vegetable, Sprouts, Alfalfa-Clover
  • Molecular Results Available:
  • Unknown
  • Test Results:
  • None
  • Location(s):
  • Many
  • Brand Name(s):
  • Product Subject to Recall:
  • Unknown
  • Total ill:
  • 68
  • Number ill by Case Definition Known:
  • Yes
  • Number Laboratory Confirmed Cases:
  • 68
  • Number Probable Cases:
  • 0
  • Number Possible Cases:
  • 0
  • Anyone Hospitalized:
  • Unknown
  • Number Hospitalized:
  • Unknown
  • Any Deaths:
  • No
  • Number Dead:
  • 0
  • Any References:
  • Yes

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