Leila:  According to the APHA Control of Communicable Diseases Manual (p251)
Listeriosis "occurs sporadically ; however, several outbreaks have been
recognized in recent years, occurring in all seasons.  About 30% of clinical
cases occur within the first 3 weeks of life."  Other than birth, person to
person contact may occur venerally.   Regarding the reservoir..."the
principal reservoir of the organism is in forage, water, mud and silage.
The seasonal use of silage as fodder is frequently followed by an increased
incidence of listeriosis in animals."  Cheese and other products from
unpasteurized milk are the main cause of outbreaks in  humans.  Thus, it is
possible that the cole slaw outbreak was caused either by the cabbage OR by
the milk products used.  Incubation is 3-70 days; the period of
communicability after birth is is 7-10days.

The problem is that we don't know exactly which ingredients do the "active"
work; thus, cosmetic companies (and even one company targeting bf moms, as
well as those who want to "dry up") are now grinding up entire cabbage
leaves to include in their ingredients.  There is some synergistic effect,
which has blocked the ability to isolate one ingredient.  IMHO, LLLI tends
to be exceedingly conservative regarding certain things.  This is one of
them.  Now that I'm retired as an LLLL and don't speak officially for them I
can say that.  I do know that cabbage leaves have been scientifically
demonstrated to reduce swelling in athletic injuries.   As for washing,
there are two recommended methods (no agreement):  soapy hot water or
diluted bleach and water.  Microwaving them should kill listeriosis I hope
that helps a bit.
Chris
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