Sprout Food-Borne Illness Outbreaks

Until the development of ISS’s trusted and proven process for screening sprouting seeds, sprout seeds were the root cause of many outbreaks of food-borne illness. At ISS, we have been involved in the sprouts industry since its inception and have led the industry in mitigating the risks of outbreaks and making sprouts a safe food to grow and eat. This page chronicles some of the challenges our industry faced in its earliest years.

Data Concerning Historic Sprout Outbreaks

According to the Center for Science in the Public Interest, in a paper called “Outbreak Alert! 2002, “Closing the Gaps in Our Federal Food-Safety Net”, sprouts made up 7% of the outbreaks from fruit and vegetables during the period of 1990-2002 (September).

Produce Outbreaks

1990-2002

Vegetables

Potatoes3%
Mushrooms4%
Home-canned vegetables5%
Sprouts7%
Produce Dishes9%
Other Vegetables14%
Lettuce11%
Salad28%

Fruit

Melon2%
Berries4%
Other Fruits13%
Total100%

Table 1. Sprouts were suspected in 7% of the produce related outbreaks from 1990 to 2002

Sprout Related Outbreaks

Although there have been documented outbreaks in sprouts since 1973, federal regulators, public health officials, and the sprouting industry did not wake up to dangers associated with sprouting until about 1996.  All parties concerned, including ISS, were bent on coming up with a way to sanitize the seed.  Between 1998 and June 2006, there have been 36 reported outbreaks in the world that were attributed to sprouts.  Twenty-seven of which involved US and/or Canadian sprout growers.

US Sprout Related Outbreaks 1996 – 2004

(FDA figures)

Year

Alfalfa sprouts & mixes with alfalfa sprouts

Clover sprouts

Mung bean sprouts

Total

Outbreaks

Cases

1996

1

1

2

650

1997

3

3

277

1998

3

3

48

1999

5

1

6

389

2000

1

1

75

2001

1

2

3

88

2002

1

1

2

21

2003

5

5

52

2004

2

2

36

Total

21

2

4

27

1633

Table 2.  Sprouts were suspected in 27 outbreaks and 1633 cases from 1996 to May 2005

Update:  There have been additional US sprout related outbreaks reported since 2004.

Several of the Outbreaks Appear to be Related

  • Three separate bean sprout outbreaks of Salmonella were reported to be the SAME phage type. (18245289)  According to the Canada Communicable Disease Report,

“This outbreak represents the first known occurrence of SE PT 913 infection in humans.” (18)

  • Three separate alfalfa sprout outbreaks of E.coli 0157:H7 were reported to have the SAME PFGE pattern.(31101According to the investigative report,

“These Pulse patterns had never been previously identified in the United States.” (31)  

  • One outbreak reportedly involved FOUR strains of salmonella in ONE seed lot.  From the report:

“Six opened packages of alfalfa sprouts were taken from cases’ homes? Two packages were positive for S. paratyphi B var java, PT “Worksop”, PFGE pattern A1. One package was positive for S. litchfield, one for S. thompson and one for S. newport; one package was negative.” (33)

  • A 1996  outbreak appears to have matched the seed from a 1995 outbreak.  From the report on the 1996 outbreak:

“PFGE testing on four isolates from University A students and two from University B students showed them to be identical to the 1995 outbreak strain.” (117)

Sprouting Seed Often to Blame for Outbreaks

Since 1988, with one exception, seed have been the likely source of contamination in every outbreak in which the source was determined.

World Sprout Related Outbreaks 1988 – Early 2005

(Food Standards Agency, UK.)

Year

Pathogen

Cases

Location(s)

Type of sprout

Likely source of contamination

1988S. Saint-PaulS. Havana, S.Muenchen148SwedenMungND
1988S. Saint Paul143United KingdomMungSeed
1988S. Virchow7United KingdomMungND
1989S. Gold-Coast31United KingdomCressSeed and/or sprout grower
1990S. Anatum15WashingtonAlfalfaND
1992S. enterica272FinlandAlfalfaND
1994S. Bovis mordificans492Finland, SwedenAlfalfaSeed
1995S. Stanley242Finland, 6 US StatesAlfalfaSeed
1995S. Newport154Denmark (Probably USA and Canada)AlfalfaSeed
1995S. Newport1337 US States, Canada, DenmarkAlfalfaSeed
1996E. coli O157:H75,727JapanRadishSeed
1996E. coli O157:H7126JapanRadishSprout growers
1996S. Montevideo and S.Meleagridis492California, NevadaAlfalfaSeed and/or sprout grower
1997S. Anatum & S. Infantis109Kansas, MissouriAlfalfaSeed
1997E. coli O157:H7794 US StatesAlfalfaSeed
1997E. coli O157:H7108Michigan, VirginiaAlfalfaSeed
1997S. Meleagridis78CanadaAlfalfaSeed (organic)
1997S. Senftenberg60California, NevadaAlfalfaSeed and/or sprout drum
1998S. Havana182 US StatesAlfalfaSeed
1998S. Cubana225 US StatesAlfalfaSeed
1998E. coli O157:H78California, NevadaAlfalfa, CloverSeed and/or sprout grower
1999S. Mbandaka754 US statesAlfalfaSeed
1999S. Muenchen>157Multistate, USAAlfalfaSeed
1999S. Saint-Paul,36California, USACloverND
1999S. paratyphi var Java51CanadaAlfalfaSeed
1999S. typhimurium120ColoradoAlfalfaSeed
2000Salmonella spp.22California, USAAlfalfaND
2000S. Enteritidis PT 4b27The NetherlandsMungSeed
2000S. Enteritidis754 US statesMungND
2001S. Enteritidis PT 91384CanadaMungSeed
2001S. Kottbus314 US statesAlfalfaSeed
2002S. Enteritidisn/aMaineMungND
2003S. Saint-Paul>9Oregon, WashingtonAlfalfaND

ND = Non Determined

Table 3.  Seed was suspected in all but one of the outbreak in which a likely source was determined.