Page 160 - The Veterinary Laboratory and Field Manual 3rd Edition

Parasitology 129

See Figure 3.13 for the life cycle of Trichinella for Terrestrial Animals which is available online
spiralis. (see text box). Regional food safety regulations
Owing to its significant public health conse- will usually stipulate what testing is required for
quences any trade of meat products that might retail of pork and high-risk meat, such as wild
contain T. spiralis requires an appropriate level boar and other wild game (see also Figure 3.13).
of testing. A detailed protocol is outlined in the Adequate cooking of meat will kill T. spiralis but
OIE Manual of Diagnostic Tests and Vaccines some traditional forms of curing meat will not.

Figure 3.13 The life cycle of Trichinella spiralis is complex and because of their short lifespan, the
adult worms are rarely found in natural infections. (A) the adult nematode lives in the small intestine
of a rodent (or other host) and liberates larvae which encyst in muscle tissue. The infected tissues of
the host are ingested by omnivorous or carnivorous species such as domestic and wild pigs or bears.
(B) The encysted larvae encyst in the ingested are liberated tissues liberated to become adult worms
in the intestine of the pig. (C) The fertilized female worms produce larvae which encyst in the tis-
sues of the pig. (D) Pork (wart hog or bear meat) is ingested by humans and released larvae become
adults in the intestine and then further produce larvae which enter the circulatory system and encyst
in muscle. The migration of Trichinella sp. larvae in human tissues may result in severe anaphylac-
tic (allergic) reaction and death several days after eating the infested meat. Infection in humans
(Trichinosis) can be prevented by ensuring that pork meat and that of wild pigs and/or bears is well
cooked before consumption. (E) Pigs may become infected when fed waste food. Infection in pigs
is prevented by not feeding waste food and controlling rodents in piggeries.

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