Hepatitis A Associated with Consumption of Frozen Strawberries --
Michigan, March 1997
In March 1997, a total of 153 cases of hepatitis A were
reported in Calhoun County, Michigan (1990 population: 136,000);
151 case-patients have been students or staff of schools in four
different school districts. Investigation by public health
officials has not implicated a single event, foodhandler, or
contaminated water as a source for the outbreak. However, most
case-patients ate lunch in schools, and preliminary analysis of
both a case-control and cohort study conducted in two different
school districts established a strong association between illness
and consumption of food items containing frozen strawberries. This
report presents the preliminary findings of the ongoing outbreak
investigation.
The strawberries associated with illness were reportedly from
Mexico; a company in southern California processed, packed, and
froze the strawberries in 30-pound containers for commercial use
and then distributed the strawberries to U.S. Department of
Agriculture (USDA)-sponsored school lunch programs. In addition,
multiple packing sizes were distributed to other commercial
customers. Thirteen lots of frozen strawberries, processed on three
dates in April and May 1996 and shipped to Michigan in early
December, were available for use in school lunch programs in
Calhoun County during the potential exposure periods for the
case-patients. The investigation has not determined whether
transmission was limited to a portion of the 13 lots or the source
of the contamination.
The Food and Drug Administration is working with CDC and USDA
to determine whether any frozen strawberries or products made from
the strawberries are still in distribution and need to be recalled.
USDA has notified state agencies to place an immediate hold on all
unused product and to contact school districts to hold all unused
product distributed already. States other than Michigan that
received the implicated lots for the school lunch program are
Arizona, California, Georgia (from a distributor in Florida), Iowa,
and Tennessee.
CDC notified the health departments in the six states that
received these lots for their programs and recommended that they
determine whether the frozen strawberries were served. Postexposure
prophylaxis with immune globulin (IG) should be offered only to
persons who consumed frozen strawberries from the suspected lots
through school lunch programs within 14 days of their exposure.
Because of the limited supply of IG nationwide, these criteria for
administration of IG should be strictly applied. Health-care
providers and public health departments should be alert to any
increase in the incidence of hepatitis A and should investigate
cases rapidly. Hepatitis A cases suspected to be associated with
the consumption of frozen strawberries should be reported promptly
to local or state health departments, and CDC's Hepatitis Branch,
Division of Viral and Rickettsial Diseases, National Center for
Infectious Diseases should be notified (telephone {404} 639-2709).
Information regarding IG for postexposure prophylaxis should
be obtained from state health departments. Information about the
prevention of hepatitis A can be obtained from the recommendations
of the Advisory Committee on Immunization Practices (1).
Reported by: Calhoun County Dept of Public Health, Battle Creek;
Michigan Dept of Community Health; Michigan Dept of Agriculture;
Michigan Dept of Education. Food and Drug Br, California Dept of
Health Svcs. Food Distribution Div, Food and Consumer Svc; Fruit
and Vegetable Div, Agricultural Marketing Svc, US Dept of
Agriculture. Detroit District, Detroit, Michigan; Los Angeles
District, Los Angeles, California; Food and Drug Administration.
Hepatitis Br, Div of Viral and Rickettsial Diseases, National
Center for Infectious Diseases, CDC.
Reference
CDC. Prevention of hepatitis A through active or passive
immunization: recommendations of the Advisory Committee on
Immunization Practices (ACIP). MMWR 1996;45(no. RR-15).
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