Pigs are carnivorous, and many of them eat rats. Sometimes the rats are infected with Trichinella spiralis, a
parasitic roundworm. Humans may become infected by eating raw and uncooked pork (or the meat of many
other carnivorous and omnivorous animals). Almost any species of mammal can become infected, with there
being a higher incidence in cats, naturally.
The worm lodges itself in muscle fibers, encased in a cyst. When the muscle of an infected pig is not
sufficiently cooked to destroy the worms, and a person eats it, he or she's stomach's digestive juices will free
the encysted worm, allowing it to circulate throughout the body. Intestinal effects may be felt after 24 hours,
including: diarrhea, nausea, abdominal cramps, and general malaise. After 7 days, the females release larvae
that circulate to the striated muscles where they encyst. The encysted Trichinella larvae may remain viable
for up to several years.
As few as five larvae per gram of body muscle can cause death, although 1,000 larvae per gram have been
found in individuals who died from causes other than Trichinosis. As the worms are invading muscles, there
may be fever, facial (particularly periorbital) swelling, and muscle pain, general edema, and weakness. The
extraocular muscles are usually the first to be affected, followed by the muscles of the jaw and neck, limb
flexors and back. In severe cases, an infected person may develop the condition known as myocarditis, which
usually develops after the third week. Death may occur between the fourth and eighth weeks if the symptoms
turn severe, especially if the central nervous system is affected. Trichinella myocarditis is rare, but
life-threatening. 10-20% of patients with Trichinella have central nervous system damage. The mortality rate
is 50% for this group, if they do not get treated.
There is no official treatment for Trichinella infection. A number of drugs may slow or alleviate the infection,
but often they have limited success. The decision to treat is based upon symptoms, exposure to raw or
undercooked meat, and laboratory test results. Steroids are sometimes used for infections with severe
symptoms, plus mebendazole, with albendazole as an alternative. However the latter two drugs are FDA
approved for investigation purposes only.
Diagnosis of Trichinella infection is crucial to determining the method of treatment. Traditional diagnostic
methods are muscle biopsy, eosinophilia, and sedimentation rate. Serologic tests are also very helpful, the
standard two being the enzyme immunoassay (EIA or ELISA) and the bentonite flocculation (BF) tests, which
are recommended for trichinosis diagnosis. A positive reaction with both types of tests indicates infection with
Trichinella spiralis within the last few years.
Discovery of Trichinella infection in humans was due to the calcified granules that are created in the muscles
of the host. In 1835, James Paget, who was studying medicine in London, noticed that his scalpels were
becoming dull due to gritty particles in the muscle of the cadaver he was working on. He noticed the wormlike
structure of them and showed them to the anatomist Richard Owen, who eventually gave them their scientific
Preventative measure are the surest way of avoiding infection. Smoking, salting, and drying meats are not
effective. The popular recommendation states that 'all parts of muscle tissue must be heated to a temperature
not lower than 137 F (58.3 C)'. Microwaving the meat is not proven safe.