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TRICHINIASIS (Trichinosis)

Categories: Animal Parasites

The disease is caused by the trichina
spiratis, a parasite introduced into the body by eating imperfectly cooked

flesh of infected hogs. The "embryos" pass from the bowel and reach the

voluntary muscles, where they finally become "encapsulated

larvae,"--muscle trichinae. It is in the migration of these embryos that

the group of symptoms known as trichiniasis is produced.



When the flesh containing the trichinae i
eaten by man or by any animal

in which the development can take place, the capsules are digested and the

trichinae are set free. They pass into the small intestine and about the

third day attain their full growth and become sexually mature. The young

produced by each female trichina have been estimated at several hundred.

The time from the eating of the flesh containing the muscle trichinae to

the development of the brood of embryos in the intestines (bowels) is from

seven to nine days. The female worm penetrates the intestinal wall and the

embryos are probably discharged into the lymph spaces, thence into the

venous system, and by the blood stream to the muscles, which constitutes

their seat of election. After a preliminary migration in the

inter-muscular connective tissue, they penetrate the primitive muscle-

fibres and in about two weeks develop into the full grown muscle form. In

this process interstitial inflammation of the muscle is excited, and

gradually an ovoid capsule develops about the parasite. Two, and

occasionally three or four, worms may be seen within a single capsule.

This process of encapsulation has been estimated to take about six weeks.

Within the muscles the parasites do not undergo further development.

Gradually the capsule becomes thicker and ultimately lime salts are

deposited within it. This change may take place in man within four or five

months. The trichinae may live within the muscles for an indefinite

period. They have been found alive and capable of developing as late as

twenty or twenty-five years after their entrance into the system. These

calcified capsules appear as white specks in the muscles. In many

instances however these worms are completely calcified. In the hog the

trichinae cause few if any symptoms. An animal, the muscles of which are

swarming with living trichinae, may be well nourished and healthy looking.

An important point also is the fact that in the hog the capsule does not

readily become calcified, so that the parasites are not visible as in the

human muscles.



Modes of Infection. The danger of infection depends entirely upon the

mode of preparation of the flesh. Thorough cooking, so that all parts of

the meat reach the boiling point, destroys the parasites; but, in larger

joints, the central portions are not often raised to this temperature. The

frequency of the disease in different countries depends largely upon the

habits of the people in the preparation of pork. In North Germany, where

raw ham and wurst are freely eaten, the greatest number of instances have

occurred. In South Germany, France, and England cases are rare. Salting

and smoking the flesh are not always sufficient, and the Havre experiments

showed that animals are readily infected when fed with portions of the

pickled or the smoked meat as prepared in this country.







Symptoms. The eating of trichinous flesh is not always followed by this

disease.



In the course of a few days after eating the infected meat there are signs

of disturbance of the stomach and bowels, and pain in the abdomen, loss of

appetite, vomiting and sometimes diarrhea; and yet, these preliminary

symptoms do not always occur, for in some of the large epidemics cases

have been observed in which they have been absent. Pain in different parts

of the body, general debility and weakness have been noted in some of the

epidemics. In some instances the stomach and bowel disturbances have been

so marked from the outset that the attack resembled our cholera. The

invasion symptoms develop between the seventh and tenth day. Sometimes not

until the end of the second week, and they are marked by fever, a chill in

some cases and pain and swelling and tenderness along the muscles

involved. The migration of the parasites into the muscles excites a more

or less intense inflammation of these muscles, which is characterized by

pain on pressure and movement, and by swelling and tension of the muscles,

over which the skin may be swollen. The limbs are placed in some position

in which these muscles are more at rest. Difficulty in chewing and

swallowing is caused by the involvement of the muscles controlling these

acts. In severe cases the involvement of the diaphragm and intercostal

muscles may lead to difficult breathing (Dyspnoea) which sometimes proves

fatal. Watery swelling, a feature of great importance, may be seen early

in the face, particularly about the, eyes. Later it develops in the

extremities when the swelling and stiffness of the muscles are at their

height. Profuse sweats, tingling and itching of the skin and in some

instances hives (Urticaria) have been described.



There are emaciation and anemia. In the severe cases the appearance may be

like that in the third week of typhoid fever. In mild cases the fever and

muscular symptoms subside in ten to fourteen days, in others only after

two or three months. The mortality, from one to thirty per cent, seems to

depend upon the virulence and number of parasites.



PHYSICIANS' TREATMENT. If discovered within twenty-four to thirty-six

hours, thoroughly empty the bowel with purgatives. Rhubarb and senna, or

an occasional dose of calomel may be given. Relieve the pains afterwards

and support the strength.



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