930 Scabies. 



History. Scab has been kno^^^l since ancient times in man as well 

 as in animals; Arabian doctors even mention the scab mites. The view, 

 however, that the disease is cansed exchisively by such mites was recog- 

 nized generally only in the past century. In the 16th century Pare 

 already knew that the parasites bore passages in the skin, and Bonomo 

 & Cestoni (1687) designated them as the true originators of scab. 

 Wedel (1672) discovered the parasites in cats, Kersting (1789) in 

 horses, Walz (1809) in sheep, Gohler (1812) in cattle and dog; finally 

 Spinola (1846) in the pig, and as early as 1791 Wichmann succeeded 

 in transmitting scab from horse to man. In the first half of the last 

 century the etiology of the disease was given a sure foundation by 

 exact clinical observations, as well as by the investigation of the biolog>^ 

 of the mites. This is evident with respect to scab of man in Hebra's 

 textbook (1844), -sdth respect to that of the domestic animals in those 

 of Gurlt, Hertwig (1844) and Gerlach (1857). More recent researches 

 (Fiirstenberg, Megnin, Railliet, Johne and others) have ascertained the 

 part played by the parasites in the production of scab in the individual 

 species of animals. 



Occurrence. Scab is a frequent disease of domestic ani- 

 mals, and occurs sometimes sporadically, at other times as an 

 enzootic, in practically all countries. The greatest extension 

 occurs in animals living in flocks which are insufficiently cared 

 for. 



Scab of the Horse. In Germany in the rears 1S02 to 1908 a total of 10,289 

 horses fell ill; the number affected varied between 425 (1897) and 959 (1908); 

 out of every 10,000 horses 1.2, 1.6, 1.5, 1.5, 1.6 and 2.2 were affected in the years 

 1903-190S. The greatest spread of scab in recent years occurred especially on the 

 east Eussian boundary in the government districts of Gumbinne, Konigsberg, 

 Danzig, Marienwerder, Posen, but in the years 1901-190.3 also in Bavaria 

 (Upper, Lower Bavaria, Lower Franconia) ; in the year 1908 the government 

 districts of Marienwerder, Danzig, KonigsV)erg, Gumbinnen, Potsdam, Allenstein 

 and Breslau were particularly infested. 



In Austria in the years 1891-1900, 3,438 horses were affected with scab, the 

 number varying between 190 and 617 (1899). The highest number of cases 

 occurred in Galicia, in which province 2,454 cases were reported. Dalmatia follows 

 next. 



In Eussia between 1895-1896 there were 4,717 horses ill with scabies. 



In Sweden in the years 1892, 1894-1895 there were 193 cases. 



In Hungary 35,881 horses suffered from scab in the years 1894-1905; the 

 number of cases varied between 949 (1898) and 5,895 (1901). The highest 

 figures of morbidity were observed in the southeastern counties. 



Scab of the Sheep. In Germany sheep scab used to be very widespread; 

 in the years 1883-1884, about 260,000 sheep were affected, and of these 78,557 were in 

 Alsace-Lorraine (61% of the total). Since energetic measures of eradication 

 were enforced there has been a decided decrease in the number of cases. In the 

 years 1892-1908 a total of 1,448,122 cases of sheep scab was reported, and the 

 frequency varied in individual years between 53,955 (1906) and 143,468 (1901); 

 in the year 1903 out of every 10,000 sheep 72.56 were affected, but in the years 

 1905-1908 the frequency per" 10,000 was 71.32, 68.24, 102.76 and 132.68. ' The 

 greatest extension of sheep scab occurred in the government districts of Kassel, 

 Hildesheim, Erfurt in the districts of Jagst and of the Danube. 



In France sheep scab apparently does not occur frequently; the greatest 

 extension occurs year by year in the northern, northeastern and the western de- 

 partments. 



In Great Britain the disease is noticed annually in all parts of the country, 

 but it occurs most frequently in the Welsh counties. From 2,000 to 4,000 flocks 

 are annually affected. 



