Man usually acquires the echinococcus from the clog, which is so frequently the intermediary of the tapeworm. Echinococcus-cysts are often given to the dog in meat at slaughter-houses, butcher-shops, and provision-stores; and even in private houses. The dog that carries the ttenia echinococcus may directly infect man with the eggs, by licking hint; or they may be deposited by the dog, on various artieles of use, such as plates, drinking-vessels, etc., and so indirectly reach human beings. Dogs that are free from echinococcus may also become the carriers of the eggs through sniffing and smelling infected animals or their evacu ations. Considering these facts, the physician should hold it his duty to warn parents of the danger that can arise from intimate contact with dogs.
The diagnosis of echinococcus is made probable by the discovery of a cystic tumor, commonly located in the liver, especially if close contact with a. dog has occurred. The hydatid thrill, which may sometimes be demonstrated by percussion ancl palpation, depends upon the trembling of the hard, gelatinous mass, which is made to vibrate; and this thrill is a decided help in diagnosis. The diagnosis is positive only when the hooklets ? 61),
the heads of the parasite, or portions of the cuticular layer are found in the fluid evacuated spontaneously after puncture or incision. Chem ical investigation of this fluid will give further diagnostic aid, as will also the formation of precipitin in the same when brought into contact with the serum of a tamia immune (Langer, 1905). The leakage of echinococcus-fluid following exploratory puncture, with all its harmful results, must be kept in mind in every case.
The prognosis depends upon the size of the echinococcus, the function of the organ affected, and the possibility of operative extir pation—which is, after all, the only rational therapeutics.
Genuine prophylaxis comes from our knowledge of the life-condi tions and the mode of transference of the parasite to man. Anthel mintic cures should be carried out, from time to time, on dogs that are house-companions; and the possibility of fresh infection should be guarded- against as much as possible.