Taken from an e-mail I received from Dr Mohamed Tahir, Singapore on Sunday, 3 April 2011 at 4:12 PM (edited for blog post).
Your blog on pork and tapeworms is good and you are giving a public health message. However it is worth while emphasizing the difference between the beef tape worm and pig tape worm infections. Although both are called tapeworms, the disease that T solium causes is much more serious.
In the T saginata infection, the average patient is symptomless, though there may be times when segments appear in the stool or wriggle out. It is not possible to pull out the whole worm physically however as they usually attain several metres in length, sometimes attaining 10 m with thousands of segments. The only symptoms there are may be vague abdominal discomfort and loss of weight, despite a voracious appetite because most of the host’s nutrition is taken by the worm. Rarely and in very severe infections there may be vomiting, diarrhea, anemia and debilitation.
It is a very different story with T solium, as in this case the larval forms of the tapeworm can invade human tissue, often with serious consequences. The embryos liberated from the eggs can penetrate the intestinal mucosa and are carried in the bloodstream to the voluntary muscles and the brain where they prefer the grey matter. They have also been found in the eye, heart, liver, lungs, pancreas and skin. Characteristic clinical features are palpable subcutaneous cysts and epileptic fits. Fulminating cases in which there is massive infection of the brain may prove rapidly fatal. There may also be symptoms of a rapidly expanding intracranial lesion leading to coma and death. To top it all, unlike T saginata which can be easily eradicated with drugs, treatment of T solium is very unsatisfactory (since the cystircerci are within the human tissues) and consists of palliative measures only. The only way is prevention ie by not eating pork.
Another interesting fact about eating pork, is something I read about in a scientific magazine some years back, but I am unable to trace it now. When pork is eaten it is broken down into component amino acids, fatty acids etc before actual absorption in the human gut. Normally such component parts are re-utilized to make human tissue such as muscle or stored as human fat. However, after absorption of pork these components recombine into pig tissue and are stored as such in the body. So there is actually a bit of pig in a pork eater!