18 September 2003
Salmonella Montevideo in sesame seed-based products
imported into Australia and New Zealand may have implications for Europe and
Leanne Unicomb1 (email@example.com),
Martyn Kirk2, Geoff Hogg3, Peter Jelfs4,
Greg Simmons5, Joy Gregory6, Carolyn Nicol7,
and the Eurosurveillance editorial team (firstname.lastname@example.org)8.
1OzFoodNet, Hunter Public Health Unit, Newcastle,
Australia;2OzFoodNet, Department of Health and Ageing, Canberra,
Australia; 3Microbiological Diagnostic Unit Public Health Laboratory, Melbourne,
Australia; 4Institute of Clinical Pathology and Medical Research,
Sydney, Australia; 5Auckland District Health Board, Auckland, New
Zealand;6OzFoodNet, Department of Human Services, Melbourne, Australia;
7Institute of Environmental Science and Research Ltd, Porirua, New Zealand;
8Eurosurveillance editorial office
Since November 2002 Salmonella
been detected in three food products imported into Australia and one product
imported into New Zealand. This report summarises investigations into these
contaminated products on behalf of the Communicable Diseases Network of Australia
and New Zealand health agencies and discusses implications for Europe and
In Australia, S. Montevideo was detected in unopened imported
tahini (sesame seed pulp, also known as tahineh) from Egypt, following the
investigation of increased human infections in November 2002 in New South
Wales. A specific laboratory survey of sesame seed-based products isolated
the same serotype in helva (also known as halva; a sweet made from tahini)
from Lebanon in April 2003. S. Montevideo was again isolated from
tahini originating in Lebanon following routine testing in August 2003 by
a commercial food producer in a separate Australian state, Victoria.
New Zealand also experienced an increase in cases of S. Montevideo
infection in 2002 with 21 cases compared to 5 cases in 2001. Health agencies
detected S. Montevideo in commercial hummus dip (made with chickpeas
and tahini) in July 2003 following investigation of a customer complaint.
The hummus was prepared locally in New Zealand. The Egyptian tahini used
to prepare this hummus dip was also found to be positive for S.
The Egyptian tahini imported into Australia and New Zealand
were made by the same manufacturer. The Lebanese helva and tahini had the
same brand name and came from the same importer/distributor, which were
different from the Egyptian products. All of these positive tests resulted
in public recalls of contaminated products (http://www.foodstandards.gov.au/recallssurveillance/foodrecalls/currentconsumerlevelrecalls/tahinehmicrobialsalm2190.cfm).
Health agencies in New South Wales identified 55 human cases of S.
Montevideo linked to the Egyptian tahini. In Victoria, there have been three
cases of S. Montevideo possibly linked to tahini and/or hummus
products, but no definitive links to recalled products have been confirmed
yet. There were no human infections detected in association with the Lebanese
helva. There were also human cases associated with the products in New Zealand
where investigations are continuing.
Pulse field gel electrophoresis (PFGE) analysis performed on the human
and Egyptian tahini samples in Australia has shown the strains to be indistinguishable.
This pattern was also indistinguishable from isolates obtained from the
helva and the recently recalled Lebanese tahini. The Australian 'outbreak'
pattern is also indistinguishable from human and food isolates from New
Montevideo is an uncommon serotype in Australia and New Zealand. These
investigations and positive food tests show that there is an ongoing problem
with contaminated sesame seed products from the Middle Eastern region of
the world. Testing of tahini showed that the concentration of salmonella
was low and detection sporadic. Routine testing of imported foods may not
isolate salmonellae, but concentrations are still sufficient to cause human
illness. This is particularly true when they are used as ingredients in
other foods, which may provide an environment more suitable for bacterial
In the spring of 2001 an outbreak of 25 cases of S.
Typhimurium definitive phage type (DT) 104 occurred in Sweden that was due
to the consumption of contaminated helva (1). The contaminated helva had
been manufactured in Turkey. Within the European surveillance system, Enter-net
there have been no increases reported recently in the incidence of S. Montevideo
in any particular collaborating country.
Human infections associated with these products continue to occur. Countries
detecting an increase in human infections of S. Montevideo should
consider sesame seed based products as a source of infection and include
appropriate questions in hypothesis generating interviews.
- Andersson Y, de Jong B, Hellström L, Stamer U, Wollin R, Giesecke
J. Salmonella Typhimurium outbreak in Sweden from contaminated
jars of helva (or halva). Eurosurveillance Weekly 2001; 5(29):
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