Investigation into the disease of sheep called "scrapie" (Traberkrankheit, la tremblante) : with especial reference to its association with sarcosporidiosis / by J.P. M'Gowan ; with an appendix on a case of Johne's disease in the sheep.
- M'Gowan, J. P. (John Pool)
- Date:
- 1914
Licence: Public Domain Mark
Credit: Investigation into the disease of sheep called "scrapie" (Traberkrankheit, la tremblante) : with especial reference to its association with sarcosporidiosis / by J.P. M'Gowan ; with an appendix on a case of Johne's disease in the sheep. Source: Wellcome Collection.
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![there is no evidence of the disease being carried by ectozoa; and the fact that the disease had been kept going in the laboratory for class purposes by feeding healthy animals on the infected flesh of their dead fellows demonstrates the efficiency of this as a method of carrying on the disease. He gives a single observation which he states goes to show that these parasites may not be transmitted from parents to young. In the autumn of 1901, only two adult grey mice were left from a lot infected during the year. A litter of three young were born about that time, and these were allowed to live until January 19, 1902, when they were three-quarters grown. Al] were chloroformed. The pair of adults were heavily infected, but no parasites could be detected in any of the young. This is possibly the first reference in the literature to the question of the disease being passed on by congenital infection. It will be seen that Smith guards himself by saying that the parasites may not be trans- mitted. Apart from this altogether, although the pair of adults were heavily infected at the time when all were killed, there is nothing to show what their condition was when the young ones were born; and, again, there is no record of the exact age of the young mice when they were killed. It is quite possible that they were too young for the parasites to be evident, more especially if, as might quite well be the case, they received a very light infection from their mother, who can quite well be supposed to have been in an early stage of the disease at the time of their birth. Koch (5), in 1904, infected mice with sarcosporidiosis by feeding them on flesh from other sarcosporidially infected mice ; and L. Négre (6), in 1907, further confirmed Theobald Smith’s observations. He also found (1) that young mice were much more easily infected than old ones. (2) That parasites only appear in the muscles forty-five days after the ingestion of spores, and their appearance may be much later. (3) The evol- ution of the sarcocyst takes place in eighty to ninety days, counting from the date of ingestion: it is at the end of this evolution that the spores have their maximum infecting power. (4) In the same mouse and in the same muscle parasites are found in various stages of development; at the end of infection the parasites of the abdominal muscles are more developed than those of the other muscles. When the infection is benign, it is 4](https://iiif.wellcomecollection.org/image/b32862040_0127.jp2/full/800%2C/0/default.jpg)
