[ANIMAL PARASITES 51]
TRICHINIASIS (Trichinosis).—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 is 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.
[52 MOTHERS' REMEDIES]
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.