Salmonella Typhimurium Infections Transmitted by Chlorine Pretreated Clover Sprout Seeds

Salmonella Typhimurium infections transmitted by chlorine-pretreated clover sprout seeds.

Am J Epidemiol 2001 Dec 1;154(11):1020-8

Erratum in: Am J Epidemiol 2002 May 15;155(10):980
Brooks JT, Rowe SY, Shillam P, Heltzel DM, Hunter SB, Slutsker L, Hoekstra RM, Luby SP.
Epidemic Intelligence Service, Division of Applied Public Health Training, Epidemiology Program Office, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.

Raw seed sprouts have caused numerous outbreaks of enteric infections. Presoaking seeds in a 20,000 mg/liter (ppm) calcium hypochlorite solution before sprouting is recommended to reduce bacterial contamination and infection risk. In 1999, the authors investigated an outbreak of Salmonella serotype Typhimurium infections in Colorado. In a case-control study, they matched 20 cases with 58 controls by age, sex, and telephone prefix; 10 (52%) of 19 cases and no controls recalled eating raw alfalfa-style sprouts in the 5 days before the patient’s illness (p < 0.00001). Traceback implicated clover sprouts grown from seeds shared by two sprouters. The time period and region over which these sprouts were sold matched the occurrences of 112 culture-confirmed illnesses. Only one of the sprouters presoaked seeds as recommended, and fewer infections were attributable to this sprouter (0.29 vs. 1.13 culture-confirmed infections/50-pound (110.1-kg) bag of seed). After recall of the implicated sprouts and seed, S. Typhimurium illnesses declined. Contaminated raw clover sprouts can cause outbreaks of enteric illness. Presoaking contaminated seeds in a 20,000 mg/liter calcium hypochlorite solution reduces, but does not eliminate, the risk of infection. Until safer production methods are developed, persons eating raw sprouts continue to risk developing potentially serious gastrointestinal illness.


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August 4, 1999

Recall Notice


Dover Sales Company, Inc. Recalls Crimson Clover Seeds


Piedmont, OK (SafetyAlerts) – The Food and Drug Administration (FDA) today reported that Dover Sales Company, Inc. is recalling Crimson Clover Seeds, in 50 pound three ply paper bags, because the product may be contaminated with Salmonella Typhimurium. These seeds were associated with an outbreak of Salmonella Typhimurium in Colorado.

This is the first public notice issued by the FDA.


Lot W8-8-CC-861.


Van Dyke Seed Company, Forest Grove, Oregon.


Dover Sales Company, Inc., Piedmont, Oklahoma, by telephone on June 4, 1999. Firm-initiated recall ongoing.


Arizona, Colorado, Florida, Hawaii, Illinois, Massachusetts, Maine, Pennsylvania, Texas, Utah, Washington state, Puerto Rico.


401 units were distributed.



“Sprouting Clover” Clover Seeds, packaged in 3 ounce resealable clear plastic bags. Product is sold in 1999-2000 Pinetree Garden Seeds catalog as sprouting seeds, page 56, item number SP9 and as part of a “Sprouting for Health Gift” Set, page 167, item number PG7.

SP9 Packed for 1999. Product sold from 11/98 to 6/9/99.

Dover Sales Company, Inc., Piedmont, Oklahoma (supplier).

Pinetree Garden Seeds, New Gloucester, Maine (repacker)

Nationwide and Canada.

1,000 packets were distributed.

Product may be contaminated with Salmonella Typhimurium. These seeds were from the same lot as the seed lot associated
with an outbreak of Salmonella Typhimurium in Colorado.