For eons humans and tapeworms have evolved together. We know from DNA evidence that our ancestors acquired tapeworms
several million years ago and only in the last several hundred thousand years have we infected our domestic animals. Most of us
are familiar with the common types of tapeworm including: pig, dog, cat, goat, fish, and cow. But, the only one of any
consequence, if one is considering self-induced infection, is the cow or beef tapeworm! And this is for a simple reason; only the
beef tapeworm treats the human body as the definitive host.
But what does that mean? It means, if you become infected with anything other than a beef tapeworm you are risking your life.
To understand more completely, we need to know a little something about the tapeworm life-cycle.
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The tapeworms life-cycle starts in the intermediate host(i). They begin as small cysts, or more properly cysticercus, that are
ingested by the final host e.g. human. Once inside the final host the digestive process activates the cysts which attach themselves
to the intestinal wall and begin to grow in a series of segments known as proglottids. Eventually, the proglottids which contain sex
organs, mature and break-off. These proglottids then migrate out the host digestive system(1). These segments are motile and are
responsible for the most common and disgusting symptom of infection.
Once the proglottid has migrated out of they final host it release tens of thousands of eggs that lie dormant until being ingested by
the primary or intermediate host(2). In the case of the beef tapeworm, that would be a cow. When it is ingested the digestive
process activates the eggs which become larva that bore through the intestinal lining and into the blood stream. The larva are
pumped through out the body of the primary host and settle throughout the host body(3). And this is where the problems begin…
The larva can penetrate the blood vessel wall and infect heart tissue, muscle, and the brain. Thousands of larva will do just that
and migrate deep into any tissue they prefer and become cysts(i) that will be eaten by a new final host(4) and begin the parasites
However, the damage done to the intermediate host can be massive and it the reason that infection in humans by beef tapeworm is
considered a health nuisance, while infection by the pork tapeworm can be life-threatening
The Future of Low Tech Biologics
Things move slowly in science and for good reason. The therapeutic reintroduction of intestinal helminths back into Americans
faces a myriad of obstacles some foreseeable and others not. For, the immediate future hosting tapeworms will be limited to those
individuals with the resources or fortitude to face a host of daunting challenges. But, there is hope. A researcher in Japan has
isolated what may be the protein that holds promise to keep an over-active immune system in check. Another researcher has
found that a common laboratory mouse can be used as a surrogate to recreate part of the parasites life-cycle. And moreover, as
our body of knowledge expands science will inevitably rediscover the usefulness of these wonderfully adapted and designed
creatures. I envision the day when we will all be exposed to small, sterile doses of intestinal helminths as children so as to
calibrate our immune systems to properly catalogue the antigens that are harmful and the ones that are harmless or self.