Trichinella spiralis

Trichinella LifeCycle

Image via Wikipedia

If you read Feral Pigs: From Piglets to Problems, you might recall that Trichinella spiralis was one of the parasites mentioned. I was fortunate enough to have an Introductory Parasitology class at Virginia Tech (full of really interesting and disgusting things that induce paranoia) where this and Toxoplasma gondii were discussed, so most of this post will be thanks to notes from Dr. Zajac’s incredible class. Many of the terms included can be found defined here.

– Scientific Classification –

The definitive and intermediate host of Trichinella are in the same animal (in this diagram, a rodent). The parasite is looking for striated muscle, and therefore as a histiotrophic parasite, spends part of its life cycle within a cell or tissue where it waits for the muscle to be eaten. ANY warm-blooded animal can serve as a host.

Trichinella spiralis

Image via Wikipedia

Pigs can get infected by eating garbage, rodents or each other. As pigs are omnivorous, they may eat rats which can be loaded with Trichinella. Once infected, they may not show any sign of disease.

Human infection, on the other hand, can result in enteritis, myalgia, fever, and kidney and respiratory failure if the parasites are prevalent enough. 5 larvae per gram of muscle is fatal.

To prevent infection, cook pork thoroughly or freeze it at -15˚C for 20 days or more, depending on the size.

Parasites like Trichinella have added to the perception that pork is unsafe. In the U.S., it is less of an issue now in confined pigs since they tend to be grain fed instead of fed with raw garbage. Organic and pasture raised operations have brought about concern of the re-emergence in swine. A couple of other hosts from which one can acquire infection are bears and horses. Current Trichinella cases are mostly from undercooked bear meat and the parasites can survive freezing. There have been several outbreaks of the parasite in horse meat in France and even some U.S. horses.

:: Next post: Toxoplasma gondii ::

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