The embryo, or muscle trichina, which is from 0.6 to 1 millimetre in length, lies coiled up in an ovoid capsule, which is at first translucent, but later becomes opaque and infiltrated with lime-salts.
When trichinous flesh is eaten by man or by certain animals the capsules are digested in the stomach and the trichinae liberated. Passing into the small intes tine they become sexually mature in from two to four days, when they produce innumerable embryos. These embryos leave the intestines for the muscles, the mode of transmission being, accord ing to J. Y. Graham, through the blood stream. About two weeks after reaching the muscle they attain the larval form. The irritation caused by their presence results in an interstitial myositis and the formation of a fibrous capsule. As a rule, the capsule is occupied by only one worm, but occasionally two or three are seen together. The trichinm may thus live for years in the muscles. According to Osier, the dissecting-room and post-mor tem statistics show that from 7., to 2 per cent. of all bodies contain trichinal. Of 1000 consecutive autopsies of which he has notes, trichinm were present in 6 instances. The eating of improperly cooked pork furnishes the greatest cause of this disease in man.
Symptoms.—If only a small number of trichinae are swallowed, no symptoms follow; but, in case of a large dose, gas trointestinal symptoms—consisting of loss of appetite, vomiting, pains in the abdomen, and diarrhcea—develop within a few days. When the embryos begin to invade the muscles, which occurs between the seventh and fourteenth days, there are usually chills and fever. Myositis is present and is characterized by stiffness, tension, and pain on pressure and move ment. There may be difficulty in masti cation and deglutition, and an intense and distressing dyspncea may add to the suffering. (Edema, seen early in the face, is noted in almost all the cases. Profuse sweating, miliaria, itching and tingling of the skin, acne, urticaria, furunculosis, and herpes may occur. In protracted cases, especially, anaemia and emaciation are often great. Osier has noticed a marked leucocytosis, which may reach above 30,000, and may prove of value in forming a diagnosis.
Diagnosis.—In additicn to the above mentioned symptoms, the stools may afford important information. They should be examined with a low-power lens, under which the trichinm appear as small, silvery threads. The diagnosis, when doubtful, may be confirmed by ob taining a piece of muscle from the biceps by a small instrument called an harpoon.
Acute rheumatism sometimes resem bles this disease, but the joint swelling in the one and the great increase in the eosinophiles in the other will aid in sepa rating them. Cholera, acute polymyo sitis, and typhoid fever may also simulate trichiniasis, and must be carefully differ entiated.
Prognosis.—The prognosis should be guarded, since it greatly depends upon the number of trichinm swallowed. A favorable symptom is early diarrhoea.
Treatment.—As a prophylactic meas ure, thorough cooking should always he insisted upon when pork is utilized as an article of diet.
As soon as it has been discovered that trichinous meat has been eaten, some purgative, of which calomel followed by a saline is the most useful, should be given. Senna, aloin, rhubarb, or glycerin may be tried. For the muscular pains, hot baths and anodyne applications some times afford relief, while the bromides may secure the much-needed sleep. The patient's strength is to be maintained by easily assimilable, nutritious food.
Filaria.—The Filaria sanguinis hom inis includes a number of varieties, but the three principal ones are the Filaria sanguinis hominis nocturna, Filaria san guinis hominis diurna, and the Filaria perstans.
The FILARIA NOCTURNA is the most common form, the male measuring 33 millimetres in length and the female 155 millimetres. From the lymphatics, where it matures and brings forth its young, it reaches the blood-current. Here it is found only during the night, or, as Stephen Mackenzie has noted, in the day time when the patient is a day-sleeper.
The embryo, which is about the diam eter of a red blood-corpuscle, may be present in the blood-vessels in large numbers without causing any symptoms, but the adult worms or ova are apt to block the lymph-channels, producing lymph-scrotum, elephantiasis, or hmma tochyluria.