Better Pork - June 2016

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Better Pork June 2016 41
HERD HEALTH
togenes infection, however, is its role as
a food-borne pathogen when present as
a contaminant of deli-type foods such
as sausages, ham and cheeses. It can
cause infection in humans who eat these
contaminated foods; recall the listeriosis
outbreak linked to deli meats processed
at a Maple Leaf plant in Toronto in
2008.
Pathogenesis. After infecting a host,
Listeria monocytogenes resides as an
intracellular parasite, which protects it
from most of the immune mechanisms
used by a host to ward off invading
bacteria. The normal habitat of L. mono-
cytogenes is soil and decaying vegetable
matter. Infection in pigs occurs via
ingestion; then the bacterium penetrates
the intestinal wall and sets up a systemic
infection by spreading to organs and
tissues throughout the body.
Treatment and control. Recovery
from infection with L. monocytogenes
usually occurs spontaneously. Treat-
ment with antibiotics, preferably peni-
cillin, is recommended when fever and
illness persist. Preventing the bacterium
from contaminating refrigerated deli-
type foods effectively controls food-
borne infection.
Listeriosis is a disease caused by the bacterium
Listeria monocytogenes. It lives in the tonsils of
pigs and other animals and is shed in their feces,
where it contaminates soil and crops.