294 DISEASES OF THE DIGESTIVE APPARATUS. 



scribed by Gentilis Arnulphus toward the middle of the sixteenth 

 century. 



It makes numerous victims during damp years (snail years), 

 which are particularly favorable to the distoma and limnsea ; then 

 we observe distomiasis in an enzootic or even panzootic form ; it is 

 rare during dry years. This observed fact testifies to the enzootic 

 character of the affection in regions which are periodically under 

 water (as the Narenta district in Dalmatia), as well as in the flat 

 regions of northern Germany, the meadows of which are damp 

 and swampy. In Holstein there is, so to speak, hardly an animal 

 killed which is not infected by the parasite (Leuckart). 



Among the most remarkable distoma years, we may mention 

 1753, 1816, 1817, and 1854. The disease ravaged whole provinces 

 at these periods. In Germany the decennial period, 1850 to 1860, 

 was particularly inauspicious. For France, Davaine points out 

 nine distoma years in the first half of this century. In 1812 dis- 

 tomiasis destroyed 300,000 sheep in the vicinity of Aries ; in 1873 

 it carried off one-third of the ovine population of Alsace-Lorraine, 

 occasioning thus, according to Zundel, a loss of 1,150,000 francs; 

 in 1862 it was seen in Ireland with marked virulence, where 60 per 

 cent, of the sheep died. The number of victims which it secures 

 yearly in England is estimated to be 1,000,000. During the year 

 1876 Slavonia lost 40 per cent, of its cattle by distomiasis. In 

 Brazil, in the single district of Tondil, it occasioned the death of 

 100,000 sheep in the space of eight months. 



According to Krabbe, the hepatic fluke-worm does not exist in 

 Iceland, while it is very common in the Faroe Islands — a fact 

 which is evidently in close relation with the nature of the moUusks 

 of these countries. 



The sheep are ordinarily infested when they are brought into 

 damp, swampy, water-covered, turfy pastures, etc. The water-pools 

 which are to be found in such places are dangerous. Formerly the 

 shepherd accused a plant, the Lysimachia nummularia (" fluke- worm 

 grass"), which certainly does not possess any influence upon the 

 development of distomiasis. Lambs, and in general animals with 

 a weak constitution, like fine wool merinos, are the subjects which 

 are most exposed to contract it ; it is from these that the disease 

 secures the greatest number of victims. It is not absolutely neces- 

 sary for the animals to go to the pasture in order to be stricken by 

 it ; infection sometimes takes place in the sheep-fold, either through 



