Occurrence. Etiology. 931 



In Italy sheep scab is rather common. Most eases occur in the south pro- 

 vinces on the Adriatic Sea, although the affection is also endemic in the other parts 

 of the country. In the years 19UU-iy08, 44:4:, 2'6 4: cases were diagnosed. 



In the Netherlands 42,751 cases of scab in sheep were reported between 

 1894-1903, of which 15,482 occurred in the year 1896 and 23,626 in the year 1897, 

 while in the remaining years the morbidity varied between 380 (1894) and 5,189 

 (1898). It was always most frequent in the provinces of Oberyssel, Drenthe, 

 Friesland and Grouingeu, in which three-fourths of the cases occurred. 



In Austria a total of 11,414 cases of sheep scab was observed in the years 

 1891-1900. The most severe outbreaks occurred in Bohemia, Tyrol and Vorarlberg, 

 Dalmatia and Carinthia. 



In Hungary 77,188 sheep fell ill of scab in the years 1894-1905; the 

 morbidity varied in separate years between 1,856 (1899) and 12,582 (1891). 



In Switzerland in the years 1894-1906 a total of 6,781 eases was recorded, the 

 greater portion of them in the cantons of Waadt and Freiburg. 



In the Balkan countries (Roumauia, Bulgaria, Servia, Bosnia and Herzegovina) 

 scab is frequent, while on the contrary in Denmark, Norway, Sweden no cases have 

 been recorded in the last few years. 



In Africa sheep scab seems to be prevalent, for in Cape Colony no fewer than 

 230,587 sheep fell ill in the year 1894. In Algeria the number of affected flocka 

 varied in individual years between 5 and 42. 



Scab of Goats. In countries in which intensive goat breeding is followed 

 scab is not rare. Thus in Austria 5,407 goats were attacked in the j^ears 1891-1900, 

 most cat^es occurring in Salzburg and Dalmatia. In Bosnia and Herzegovina 

 11,560 cases of scab were reported in the years 1901-1906. In Italy in the years 

 1901-1906, the disease affected 4,556 goats; it was especially frequent in Sicily and 

 Sardinia. In the Cape Colony in the year 1894, 203,409 goats suffered from the 

 complaint; in Asia also it is a frequent disease (Cadeac). 



Scab of the Dog. Sarcoptic scab of dogs is frequent, especially in large 

 towns. Thus 6,225 out of 70,000 dogs attended in the Berlin clinic in the years 

 1886-1894 suffered from scab, while in Munich in the year 1889 of the dogs 

 receiving internal treatment 16% were affected with sarcoptic mange. — Out of 

 9,732 dogs brought to the Budapest clinic in the course of the last 15 years, 367 

 (3.8%) were found to be suffering from sarcoptic scab. Of 894 cats, 56 (6.3%) 

 were suffering from scab. 



Etiology. The mange parasites (Sarcoptida) are very 

 small mites belonging to the order of the Acarina, of the class 

 Arachnoidea. Owing to the fusion of head, thorax and abdo- 

 men, the body is rounded or oval. It is more or less grooved 

 and covered with spines and bristles. On the head may be 

 found the biting, sucking or puncturing rostrum, which is placed 

 differently in the individual varieties. The young mites have 

 three and later on four pairs of articulated extremities, which 

 ill some cases end in suckers and in others in bristles. 



The males are much smaller than the females, which lay 

 oval eggs. In the eggs embryos with 3 pairs of legs develop, 

 which, according to external conditions, but especially according 

 to the temperature, hatch in the course of 3 to 10 days. The 

 larvae change after 2 or 3 moultings to four-footed but still sex- 

 less nymphae which finally develop into sexually mature mites. 

 The complete development requires 2 to 3 weeks, and then the 

 pregnant female lays an average of 15 eggs, from which an 

 average of 5 male and 10 female mites develop. In unhindered 

 development and increase, Gerlach calculates that one pair of 

 parasites can produce half a million male and a million female 

 mites within 3 months in the sixth generation. The males live 

 5 to 6 weeks, but the females die, after laying their eggs, in 3 

 to 6 weeks. 



