Multistate Outbreak of FREE

MMWR. 1998;47:462-464

DURING April-May 1998, a total of 11 states reported an increase in cases of Salmonella serotype Agona infections; as of June 8, a total of 209 cases have been reported and at least 47 persons have been hospitalized, representing an eightfold increase over the median number of cases reported in those states during 1993-1997. The states reporting increases were Illinois (49 cases), Indiana (30), Ohio (29), New York (24), Missouri (22), Pennsylvania (20), Michigan (15), Iowa (eight), Wisconsin (six), Kansas (four), and West Virginia (two). This report summarizes the outbreak investigation by local, state, and federal public health officials, which implicated Millville brand plain Toasted Oats cereal manufactured by Malt-O-Meal, Inc. as the cause of illness.

Among 162 patients in this outbreak for whom information was available, 85 (52%) were female. Most cases occurred in children and the elderly (47% in persons aged <10 years and 21% in persons aged >70 years). Most illnesses began in May.

Officials in the 11 state health departments, in collaboration with CDC, conducted a matched case-control study comparing persons with cases of S. Agona infection in April and May with well household members (controls); conditional linear logistic regression was used to examine the relation between consumption of cereal and illness. As of June 8, information from 55 households has been analyzed; 46 (84%) of these 55 households shopped at an Aldi supermarket. During the 3 days before onset of illness, 31 (66%) of 47 patients and 32 (36%) of 89 household controls consumed Millville brand plain Toasted Oats cereal purchased at an Aldi supermarket (matched odds ratio=22; p=0.003). This association remained significant when controlled for age (p<0.05). When average daily consumption of Millville brand plain Toasted Oats cereal purchased from an Aldi supermarket was categorized into three groups (no consumption, ≤1 cup, and >1 cup), a significant dose response relation was found (p=0.003).

Culture of an open box of Millville brand plain Toasted Oats cereal obtained from the home of a case-patient yielded Salmonella Agona at CDC. The pulsed-field gel electrophoresis (PFGE) pattern of this isolate was indistinguishable from the predominant PFGE pattern among outbreak-associated clinical isolates. The Food and Drug Administration (FDA) isolated Salmonella Agona from two separate composite samples from unopened boxes. Clinical isolates were susceptible to all antimicrobial agents tested (i.e., ampicillin, trimethoprim-sulfamethoxazole, and ciprofloxacin).

The Minnesota Department of Health, the Minnesota Department of Agriculture, FDA, and CDC are collaborating in the investigation of the Malt-O-Meal, Inc. plant that manufactured the implicated cereal to determine the source of contamination. At this plant on the same production line, multiple brands of plain Toasted Oats are manufactured at different times. Malt-O-Meal has issued a voluntary recall of all plain Toasted Oats cereal produced on the same production line. Investigation is ongoing to determine whether other plain Toasted Oats cereal brands produced by the same company were contaminated. Cases of Salmonella Agona infection occurring during the same time have now been reported in California (11), Washington (nine), New Jersey (five), Tennessee (three), Oklahoma (three), Idaho (two), Maryland (two), Minnesota (two), Nebraska (one), and Connecticut (one). These cases are being investigated to determine possible links to this outbreak. CDC recommends that consumers not eat plain Toasted Oats cereal produced by Malt-O-Meal until further investigation has identified the scope, magnitude, and cause of the contamination. Questions about plain Toasted Oats cereals manufactured by Malt-O-Meal should be directed to the company, telephone (800) 590-1810.

State and local health depts. Office of Regulatory Affairs, and Center for Food Safety and Applied Nutrition, Food and Drug Administration. Foodborne and Diarrheal Diseases Br, Div of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, CDC.

Salmonella Agona is one of approximately 2000 Salmonella serotypes that can cause illness in humans. An estimated 2-4 million cases of salmonellosis occur in the United States each year, resulting in ≥500 deaths.¹ Approximately 40,000 of these infections are culture confirmed, serotyped, and reported to CDC by state health departments.¹Salmonella infections usually resolve in 5-7 days and do not require antibiotic treatment. Persons with severe diarrhea may require rehydration with intravenous fluids. Antibiotics are required when infection spreads from the intestinal tract. Salmonella Agona is an uncommon serotype of Salmonella, accounting for approximately 1.5% of human isolates reported to the Public Health Laboratory Information System (PHLIS).² Like most other Salmonella serotypes, Salmonella Agona is found in a variety of animal reservoirs including poultry, cattle, pigs, and animal feed. The first reported U.S. outbreak of Salmonella Agona infections was traced to animal feed made with contaminated imported fishmeal in 1972³; other outbreaks have been attributed to dried milk⁴ and to a commercial peanut-flavored snack.⁵ This outbreak represents the first time a commercial cereal product has been implicated in a Salmonella outbreak, although an infant cereal product was implicated in an outbreak of Salmonella senftenberg in the United Kingdom.⁶Salmonella spp. are relatively resistant to desiccation and can survive for long periods in dry environments such as cereal.⁷

Timely communication among the states and CDC about unexplained local increases in Salmonella Agona infections, and the relative rarity of this serotype, led to the identification of this multistate outbreak. Electronic national laboratory-based reporting of Salmonella infections facilitated prompt recognition of the extent of the outbreak. Cooperative investigations among federal, state, and local agencies, coordination by CDC, electronic reporting through PHLIS, and the rapid identification of related isolates using PulseNet (the national network of public health laboratories that perform DNA "fingerprinting" on foodborne bacteria) are critical components in the recognition and investigation of multistate foodborne outbreaks.

References 7 available.