SARCOPTIC SCABIES
This scabies has long been recognised as affecting more especially the head, muzzle, etc. It was mentioned as long ago as the fourteenth century by Jehan de Brie, but, until Delafond’s time, no one recognised that it was caused by an acarus. In 1858 Delafond discovered the parasite in Piedmont sheep.
Fig. 251.—Sarcoptis, magnified 100 diameters. (After Railliet.)
Causation. Formerly, writers on the subject and shepherds attributed this disease to the wounds and excoriations which sheep receive in passing through brambles, holly, etc., or in rubbing against their racks. The true cause of the disease is the presence under the skin of the Sarcoptes scabiei var. ovis, which passes from sheep to sheep by direct contact. The animals attempt to rub against everything about them, even against their neighbours. These parasites can be transferred from the goat to the sheep, and vice versâ.
Walraff, Roloff, Delafond, Gerlach and Railliet have described cases of infection in man, but the disease is rarely more than of a temporary character.
Symptoms. This form of scabies affects the head and the parts free from wool.
At first the parasites invade the upper lip and the tissues about the nostrils, sometimes, but more rarely, the eyes and ears. They cause the formation of vesicular papules, accompanied by violent itching. The animal, in rubbing itself, excoriates these papules, which discharge a fluid and soon become covered with yellowish-brown crusts.
The disease afterwards invades the face, forehead, jaws, and entire head. The skin becomes wrinkled and the brownish crusts thicker and more abundant. These are fissured and bleeding, and they give the face the appearance of one vast sore.
The parasite rarely attacks the region of the elbow, the belly, or the inside of the thigh. The disease never advances in parts covered by wool, although in breeds of sheep with thick wool, such as are found in Algeria and Tunis, the sarcoptic form of scabies may become generalised and attack the entire body. The extremities of the limbs, however, are usually attacked after all the head has become involved.