Trichinellosis - France (03)

International Society for Infectious Diseases
<http://www.isid.org>


How do horses get infected with Trichinella ?
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Have we any idea how horses get infected with Trichinella? Are they
non-veg on occasions? And if it is soil or grass contamination by
decaying rodents, why not cows?

--
Dr. Burkhard Rieke DTM&H (Liv.)
Centre for Travel Medicine
Duesseldorf, Germany


[Several studies address the question of how horses get infected with
Trichinella.

1.   Murrell KD et al. Epidemiology of Trichinella infection in the
horse: the risk from animal product feeding practices. Vet Parasitol.
2004 Sep 2;123(3-4):223-33.

The paper states: "Based on interviews of horse producers at local
horse markets, it was revealed that the feeding of animal products to
horses was a common practice. Further, it was alleged that many
horses, particularly those in poor nutritional condition, would
readily consume meat. A subsequent series of trials involving the
experimental feeding of 219 horses demonstrated that 32 percent would
consume meat patties. To confirm that horses would eat infected meat
under normal farm conditions, 3 horses were offered infected ground
pork balls containing 1100 larvae. All 3 became infected. ... It is
concluded that horses are more willing to consume meat than realized
and that the intentional feeding of animal products and kitchen waste
is a common occurrence among horse owners in Serbia (and elsewhere?).
This is a high-risk practice which demands closer scrutiny by
veterinary and food safety authorities, including the implementation
of rules and procedures to ensure that such feeds are rendered safe
for horses, as is now required for feeding to swine."

2.   Kapel CM. Changes in the EU legislation on Trichinella
inspection--new challenges in the epidemiology.Vet Parasitol. 2005
Sep 5;132(1-2):189-94

Several attempts have been made to define Trichinella-free areas, but
certification of Trichinella-free pig production farms appears to be
the only feasible approach. The increasing prevalence of the
non-encapsulating species, _Trichinella pseudospiralis_, in game,
domestic pigs and humans has eliminated the compression technique
from the new EU legislation to be enacted in 2006.

Also, the observation that several species of Trichinella tolerate
freezing in horse meat for up to 4 weeks has forced a change in
legislation as well where freezing is no longer an option for
certifying horse meat.

3.   Kapel CM et al. . Muscle distribution of sylvatic and domestic
Trichinella larvae in production animals and wildlife.Vet Parasitol.
2005 Sep 5;132(1-2):101-5. "In horses, _T. spiralis_, _Trichinella
britovi_, and _T. pseudospiralis_ all established at high levels with
predilection sites in the tongue, the masseter and the diaphragm."

Cattle can become infected with Trichinella too, but outbreaks due to
infected beef have not been reported over the past 15 years. However,
a recent study from China identified Trichinella in 2 percent of beef
samples. Wang ZQ et al. The epidemiology of animal trichinellosis in
China. Vet J. 2005 Sep 12; (Epub ahead of print).

[Horses can and will be carnivores, just as cows will be. This
moderator has watched a herd of cows stomp a skunk to death and then
tear it apart and consume it, the same as pack of dogs would. This
moderator was amazed to watch a group of horses do the same thing a
poor unsuspecting oppossum. (Also, I believe there are a couple of
British documents about similar cow incidents, but I do not have them.)

Horse owners put supplements on horses' feed. It is conceivable that
a supplement contained some trichonellae, remembering that many
animal feed supplements are not necessarily approved by FDA or other
international regulatory agencies, although there are some that
are.This moderator would guess that this is a supplement or a feed
contamination issue.