Date of this Version
Journal of Parasitology (September 1914) 1(1): 5-9.
First two paragraphs:
The question as to the length of time Cysticercus bovis may survive after the death of its host has been quite definitely settled by the researches of Perroncito, Zschocke, Ostertag and others. Perroncito (1877) found that the cysticerci in an artificially infested calf were all dead fourteen days after the slaughter of the animal. However, Zschocke (1896) succeeded in infesting the human subject with a tapeworm by feeding five cysticerci from beef kept from fourteen to sixteen days after slaughter. No infestation followed the swallowing of five cysticerci from beef kept twenty-one days after slaughter. Ostertag (1897) examined in a thermostat a large number of cysticerci from beef kept in cold storage at temperatures above freezing for various periods of time after slaughter and concluded that the parasites are no longer capable of development on the twentieth day, although slight movements were observed in a few cysticerci as ]ate as twenty-four days after slaughter. These results were confirmed by feeding experiments in which thirty-four persons swallowed cysticerci from beef held in cold storage at temperatures above freezing for from twenty to twenty-one days after slaughter. No tapeworm infestation resulted in any case.
The conclusions from these investigations are that a lapse of twenty-one days after slaughter is amply sufficient to insure the death of the beef cysticercus, and on the other hand that fourteen days is not sufficient, although in some cases: as determined by Perroncito in one instance, the parasites may have lost their vitality within this shorter period of time. Cognizance has been taken of these results in the meat-inspection regulations of Germany, United States, and other countries, which provide that beef carcasses showing infestation with cysticerci in a certain slight degree may be passed for food after retention in cold storage for twenty-one days.