The Centers for Disease Control and Prevention have released information about a 2011 outbreak of Salmonella Bovismorbificans that was linked to hummus and tahini. On September 27, 2011, three isolates of that particular strain were identified by the District of Columbia Public Health Laboratory. The outbreak sickened 23 people in seven states and the District of Columbia.
This strain of Salmonella is quite rare in the United States. Nine people who were sickened with the outbreak strain of the bacteria were interviewed by public health officials. All had eaten at restaurants in the District of Columbia or northern Virginia less than two weeks before becoming ill. Dates of illness onset ranged from August 19 to November 21, 2011. On May 30, 2012, traceback information revealed that contaminated tahini (sesame seed paste) prepared at a Mediterranean-style restaurant in DC was a “plausible source” of the infection.
The outbreak PFGE pattern was new to PulseNet, the national network of public health and food regulatory agency labs coordinated by the CDC. There have been only five other foodborne illness outbreaks of Salmonella Bivosmorbificans in the U.S. since 2001. In this outbreak, most of the cases occurred in the mid-Atlantic region of the U.S. The case count was as follows: District of Columbia (8), Maryland (7), Virginia (3), California (1), Delaware (1), Michigan (1), New Hampshire (1), and New Jersey (1).
Among the 22 patients who gave the government information, 91% ate at a restaurant in the DC metropolitan area. Fourteen, or 93%, of the 15 patients asked, ate at a Mediterranean-style restaurant in the DC metropolitan area. The restaurants were identified as A, B, and C. Public health officials isolated the outbreak strain of the bacteria from hummus collected from restaurant A.
The Department of Health issued an embargo on hummus and hummus ingredients from restaurant A on November 18, 2011. The restaurant was ordered to restrict preparation of hummus and hummus ingredients, including tahini, chickpeas, garlic, lemon juice, salt, and olive oil, and was ordered to not deliver hummus to restaurants B and C. The Virginia Department of Health conducted traceback and found a common distributor in northern Virginia that provided bulk food items for the restaurants, but all samples tested negative.
The embargo was lifted during February 2012 because no more cases were reported and food safety violations were corrected. Since no cases were reported after the embargo was imposed, public health officials decided not to issue a public health advisory. The restaurants have still not been named.
On May 30, 2012, the FDA traceback suggested that the tahini used in hummus may have been the source of the bacteria. A manufacturer in Lebanon supplied the product. That manufacturer was associated with recent Salmonella outbreaks in Canada. Salmonella can survive for long periods of time in high fat foods, if the nuts or seeds used to make those foods are not processed properly. FDA may coordinate with Canadian officials to inspect the tahini manufacturing plant in Lebanon. Public health officials are warning consumers that products made from imported sesame seed paste should be considered as possible sources for foodborne illness.
