Is there trichinosis in Australian pork

Bernhard Peter
(In case of doubt, please discuss your complaints and measures with a doctor you trust!)

What are trichinae?

Trichinae (Trichinella spiralis with several subspecies) are parasites that use carnivorous or omnivorous mammals as host animals and thus also humans. They are roundworms (nematodes) a few millimeters in length. The parasite changes host, the only important thing is the change itself, which species it is, the trichinae don't care. They feel good as long as the cycle of eating and being eaten is maintained, regardless of whether they are "guests" with a pig or with a person.


Where do trichinae occur?

The main area of ​​distribution is the northern hemisphere. There are also endemic areas in Africa, Asia, Australia and Latin America. In Europe, apart from a few outbreaks in recent decades, the risk is low thanks to consistent meat inspection.

Most of the time it is a silvatic cycle between game and predators. But there is also a paradomestic cycle in which humans and their farm animals play an important role.


What is the parasitic cycle of trichinae like?

When a carnivore (human, dog, cat, marten, fox, bear) or omnivore (human, rat, pig) or marine mammal (seal, whale) eats meat containing trichinae, these larvae are released through digestion of the surrounding tissue were previously encapsulated. The larvae settle in the lining of the mucous membrane of the small intestine. Within a few days they go through 4 moults and finally become sexually mature worms. After mating, the males die. The females live until they have each produced approx. 500-1500 larvae approx. 0.1 mm long (4-6 weeks), then they too die. The larvae pass through the intestinal mucous membrane, enter the blood and lymph vessels of the organism and allow themselves to be driven by the flow of blood to other organs and tissues of the body. The target organ is actually the skeletal muscles, because only there the larvae can develop. They can be found there at least a week after the contaminated meat has been taken in. The larva is encapsulated in the muscle tissue, after approx. 1-1.5 months an oval to lemon-shaped capsule has formed, which increasingly calcified. In this way the parasite waits for this meat to be eaten by another animal, whereupon the cycle can begin again. The encapsulated larvae are still infectious for decades. They are very resistant to environmental influences, even in rotting meat (carrion) they remain contagious for several months.



How can you get trichinae?

You get trichinae by eating meat and meat products that contain larvae that have not been killed by appropriate treatments, i.e. insufficiently heated or deep-frozen or only dried or cured.

In purely theoretical terms, it is also conceivable that animals become infected by eating feces if the producer of the same had a meal containing larvae beforehand and encapsulated larvae can be found in the feces.


How does a trichinae disease manifest itself?

The extent of the disease depends on the number of larvae ingested. But relatively few (around 50-70) are enough to cause discomfort. There are two phases:

  • Intestinal phase (roughly the first week):
    • nausea
    • Vomit
    • constipation
    • diarrhea
    • stomach pain
    • light fever
    • also latent possible (without complaints)
  • Extraintestinal phase (roughly after a week, lasts 1-1.5 months):
    • muscle pain
    • Muscle stiffness
    • Redness of the skin
    • allergic reaction
    • Characteristic changes occur in the blood count
    • Certain enzymes can be found in an elevated level in the serum
    • fever
    • rheumatoid complaints
  • Complications:
    • Myocarditis
    • Meningoencephalitis (meningitis)
    • Death (usually within 1-1.5 months after infection)
  • Long-term development:
    • either complete healing
    • or long-term rheumatoid symptoms


How can you treat trichinae?

Chemical therapy is available e.g. B. with the active ingredients albendazole or mebendazole available, which is often combined with cortisone derivatives to suppress the allergic-inflammatory reaction of the body to the alien in its organs.


How can you prevent trichinae?

  • Consistent meat inspection, purchase of meat from recognized specialist butchers, no uncontrolled game or house slaughter (although prohibited, unfortunately it still occurs often, e.g. to follow certain group-internal religious guidelines during slaughter)
  • Freezing the meat. Freezing means really deep, i.e. at least -30 ° C for at least 24 hours. Normal cooling (-4 to +2 ° C), the larvae can easily survive for up to a year.
  • Heat (boiling, frying, baking, at least 60 ° C) quickly kills the larvae.
  • Caution: drying and curing does not kill the parasites.
  • If you are not sure and have not obtained the material yourself from a perfect butcher, only consume well-cooked meat (no steak "very English" or tartare, also be careful with Bündnerfleisch and other dried or smoked varieties)
  • In general: No feeding of meat waste to domestic pigs and similar measures to prevent the spread.

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    © Text, graphics and photos: Bernhard Peter 2004