SARCOCYSTIS, TOXOPLASMA AND RELATED PROTOZOA 



339 



which are Besnoitia cysts. The nasal 

 mucosa becomes bright red and is also 

 studded with cysts. The mucosa may be 

 swollen and there may be a rapidly pro- 

 gressive rhinitis; it starts with a mucous 

 discharge which later becomes thick, 

 hemorrhagic and mucopurulent, forming 

 dark brown crusts in the nostrils. If the 

 pharynx and larynx are involved, there is 

 a short cough. This stage may last 5 to 

 10 days. The acute stage then subsides 

 and the second stage begins. 



The depilatory stage . In this stage, 

 the pathologic and clinical pictures are 

 dominated by skin lesions. The skin be- 

 comes greatly thickened and loses its 

 elasticity. The hair falls out over the 

 swollen parts, and the skin on the flexor 

 surfaces cracks and a sero-sanguinous 

 fluid oozes out. Necrosis of the skin de- 

 velops on the parts in contact with the 

 ground when the animal lies down. Toward 

 the end of this stage, hard sitfasts develop 

 on the sides of the stifles, brisket and el- 

 bows. The anasarca subsides, leaving 

 the skin with typical, broad wrinkles along 

 the lower line. The photophobia decreases, 

 and grazing is resumed in many cases. 

 Death may occur at this stage. If not, the 

 stage lasts 2 weeks to about a month and 

 gradually passes into the third stage. 



The seborrhea sicca stage . In this 

 stage, most of the hair on the previously 

 anasarcous skin has been lost, and the 

 denuded parts are covered by a thick, 

 scurfy layer. The sitfasts crack away 

 from the underlying tissues, fissures re- 

 main in the flexor surfaces, the skin 

 hardens, and deep scars show plainly. 

 The hide resembles that of an elephant, 

 and the animal looks as tho it has mange. 

 The lymph nodes are permanently en- 

 larged, the protozoan cysts remain, and 

 the animal is listless and debilitated. 



In light infections in which there has 

 been little hair loss, the animals become 

 practically normal in appearance, but in 

 more severe cases recovery requires 

 months or even years, and the changes in 

 the cutis and subcutis and the loss of most 

 of the hair are permanent. In convales- 

 cent animals the remaining hair forms 



patterns resembling the markings on a 

 giraffe. 



The morbidity in a herd varies from 

 1 to 20%, and the mortality is about 10%. 



Diagnosis : Besnoitiosis can be diag- 

 nosed by biopsy examination of affected 

 skin or other areas. The spherical, en- 

 capsulated cysts are pathognomonic. 

 There may be a severe granulomatous re- 

 action in young cysts or those which have 

 broken and released their trophozoites, 

 but there is usually little reaction except 

 for the formation of the hyaline wall 

 around the mature cysts. 



Trophozoites are often found in blood 

 smears, sometimes in large numbers, 

 but most of them are introduced when a 

 cyst is cut in obtaining blood. 



Treatment : None known. 



Prevention and Control : Until the 

 mode of transmission is learned, the ap- 

 propriate preventive measures must re- 

 main unknown. However, sanitary 

 measures would prevent the spread of 

 besnoitiosis if transmission is by ingestion, 

 and insect control would prevent it if trans- 

 mission is by biting insects, as some be- 

 lieve. 



BESNOITIA BENNETTI 

 BABUDIERI, 1932 



Hosts : Horse, ass. 



Location : Same as B. besnoiti. 



Geographic Distribution : Africa 

 (Sudan, South Africa), Europe (southern 

 France, Pyrenees), North America 

 (Mexico, United States). 



Prevalence : Relatively uncommon. 

 Bennett (1927, 1933) recorded this species 

 from 3 horses in the Sudan, all of which 

 originated in the Nuba Mountains of South- 

 ern Kordofan. Schulz and Thorburn (1941) 

 found it in South Africa. Jones (19 57) found 

 it in the skin and other tissues of small 

 burros which had been imported into the 



