HYDATID DISEASE.
Prophylaxis is of vital importance; the hydatid cyst is the result of the introduction into the human alimentary canal of the eggs of the T ania small tapeworm infesting the dog, sheep and wolf. The human hydatid is the bladder stage of this parasite's existence. The eggs find their way into the human stomach chiefly through drinking water. Hence the necessity, in districts where the parasite abounds, to look most closely to the filtration of water and the purity of food. The utmost scrupulosity should be observed as regards the personal cleanli ness of all who come into close relations with dogs. A minute worm is found in dogs in vast numbers in the small intestines, and the human hydatid is the bladder stage of this parasite. The dog becomes infected by eating the offal of sheep suffering from hydatid disease. As the mature worm does not exceed "; inch, it is easily seen how readily the minute ova in the last joint of the worm which alone contains the de veloped sexual organs may find entrance into the human stomach in water or from the soiled hands of individuals who are in the habit of caressing the dog.
Diagnosis has been simplified by the discovery of the presence of specific anti-bodies in the blood-serum of patients suffering from hydatids, the antigen being easily obtained from any sample of preserved hydatid fluid. Another aid in diagnosis is the presence of eosinophilia and of basophilia.
The surgeon should aim in every case when this is possible at complete excision of the cyst with its inner wall by carefully dissecting out the tumour from the surrounding adventitious tissue. Where this is not practicable the cyst should be freely incised, its contents thoroughly evacuated and the cavity packed with sterilised gauze, which in each subsequent dressing is to be replaced by fresh packing till the complete obliteration of the sac has been effected. The steps of the operation obviously require modification according to the nature of the organ or tissues in which the cyst has developed.
The liver is the most common site, more than half of all hydatids being found in this organ. A pedunculated cyst depending from the under surface of the liver may be easily reached by an anterior abdominal incision; a ligature having been applied to the pedicle when the neck of the tumour is long and narrow, the cyst may be removed by cutting through the pedicle below the ligature.
Ilydatids embedded in the hepatic tissue demand a different treatment; the organ being exposed by abdominal section and the cyst isolated from the peritoneal cavity by packing the edges of the wound with sponges, the wall is incised and its contents drawn off. The incision in the cyst is next enlarged so as to thoroughly expose the white parasitic wall, and whilst this is being gently drawn upon by forceps its delivery is facilitated by a jet of normal serum injected between it and the ad ventitious fibrous capsule in which it lies. The resulting cavity is then thoroughly cleansed by irrigation and its lips sutured before closing the abdominal wound.
Where the parasitic cyst wall cannot be removed, the lips of the in cision in the adventitious cyst may be sutured to the edges of the abdo minal wound and the cavity packed with gauze as in Lindemann's method. Deeper hydatids must be removed through a posterior incision over the lower ribs which will require excision so as to open up the pleural cavity, the cyst being then reached through an incision in the diaphragm.
When an hepatic hydatid cyst has already suppurated, it must be treated as an abscess. The abdomen should be opened, the purulent contents of the sac evacuated by a free incision, and after irrigation with an antiseptic solution the cavity should be packed with gauze or a free drainage provided by introducing a rubber tube after the margins of the cyst wall have been stitched to the lips of the abdominal wound.
Pulmonary and pleural hydatids can be successfully treated by excision of two or three ribs, removal of the cyst contents and of its parasitic wall, with or without drainage. Aspiration is liable to cause death in pulmonary hydatid disease, and must never be resorted to. Should suppuration occur in the pleural cavity, a free incision must be made between the ribs, and the space washed out and drained as in empyema. Abscess of the lungs, if near the surface at the base, may he successfully treated in a similar way.
Hydatid cysts in the brain have been successfully removed when near to the surface by a trephining operation; these cysts are usually sterile, containing no scolices or daughter cysts.