786 Piroplasniosis <if Horses. 



and donkeys. Positive results, also with tlie blood of affected 

 liorses, are reported by Perruc^^i, Pricolo, Edington and Bie- 

 litzer. 



According to Theiler the natural infection is transmitted 

 in Africa by the Rhipicephalus evertsi, in Russia according- to 

 Marzinowski & Bielitzer by the Dermacentor reticulatus, that 

 is by sexually mature ticks which have sucked blood containing 

 piroplasma as larvae or njanphs. As horses which have re- 

 covered from the disease harbor piroplasma for years in their 

 blood, such animals may spread the virus by transmission to 

 ticks. Zebras and quaggas appear also to serve as virus carriers. 



In infected localities native liorses, donkeys, and their bas- 

 tards, become affected in later periods of their lives only when 

 their acquired resistance is reduced by overexertion, poor nutri- 

 tion, or by intercurrent affections to such an extent that their 

 latent piroplasma again rapidly multiply. Such relapses occur 

 especially in affections of horse sickness, the course of which 

 frequently becomes severe because of such relapses. 



Animals of the horse genus which are brought from locah- 

 ties free from piroplasma to infected localities are very sus- 

 ceptible ; thus during the Boer War in South Africa great losses 

 were sustained in horses brought there from Europe and Aus- 

 tralia, and in India horses from Australia become especially 

 affected. 



Anatomical Changes. On autopsy the icteric discoloration 

 of the subcutaneous and of the subserous connective tissue, as 

 well as of the internal organs is conspicuous, after a somewhat 

 protracted course a general anemia is present which is also man- 

 ifested in the wateW consistence of the blood. The lymph 

 glands and the spleen always show pronounced acute swelling, 

 the pulp of the spleen being moderately softened but not blackish 

 red. Numerous hemorrhages are present on and in the serous 

 and mucous membranes, as well as under the endocardium, the 

 intestinal mucous membranes show inflammatory swelling, that of 

 the large intestine in some cases also contains follicular ulcera- 

 tions. The lungs are edematous, the kidneys may be sprinkled 

 with punctiform hemorrhages, or only anemic and filled with 

 serous fluid, the liver lobules are yellow, on their borders 

 greenish colored. The muscles, including those of the heart 

 show cloudy swelling, in places also fatty degeneration. The 

 urinary bladder frequently contains more or less reddish colored 

 urine. 



Symptoms. After an average incubation of about two 

 weeks the disease commences with slow or rapid rise of the body 

 temperature, whereupon the fever continues for a long time 

 remittent in character. The first visible symptom is a pale-yel- 

 low, or reddish-yellow coloration of the mucous membranes, the 

 intensity of which is proportionate to the severity of the affec- 



