PIROPLASMOSIS OF SHEEP 791 



Immunity. 



Bovine piroplasmosis does not recur in the same animal and cattle which 

 recover from a first attack of the disease are permanently immune. The 

 serum of such animals has neither therapeutic nor prophylactic properties 

 (Nicolle and Adil-Bey). Lignieres obtained promising results by vaccinating 

 cattle with an attenuated piroplasma. 



In the blood of immunized animals the piroplasma assumes a different 

 form (rings and small rods) from that presented by the parasite in animals 

 suffering from the disease. The inoculation of blood containing these parasites 

 into an healthy animal produces an illness which may terminate fatally 

 (Theiler). 



2. Piroplasma ovis. 



Synonym. Babesia ovis. 



The piroplasma infecting sheep was first described by Babes in the disease 

 known as Carceag, in Roumania. It was subsequently found by Bonome in 

 an epizootic near Padua and has been studied by Laveran and Nicolle (in an 

 epizootic in Constantinople) and by Motas (in Koumania). The parasite has 

 also been found in Bulgaria, Italy, France, South Africa and India. 



Sheep piroplasmosis occurs in two forms a severe and fatal form (with anaemia, 

 prostration and haemoglobinuria) and a mild form often not diagnosed which ter- 

 minates in recovery. One attack confers immunity. In sheep dead of piroplasmosis 

 the tissues are oedematous, the blood pink and fluid, the spleen and the lymphatic 

 glands enlarged : numerous parasites will be found in the blood and spleen. 



Appearance in the blood. The parasites measure 1-1 '5/x. in diameter ; they 

 are rounded or elongated, non-pigmented, generally contained within the 

 red cells, and have a rounded karyosome situated, as a rule, near the periphery. 

 Some of the intra-corpuscular parasites will be seen to be actively multiply- 

 ing : the karyosome elongates and then splits into two, and division of the 

 protoplasm follows. The double and pyriform parasites are as a rule free 

 but may occasionally be found in the red cells. Generally speaking there is 

 not more than one parasite in a red cell. 



Appearance in films from the spleen. The parasites are more numerous in 

 the spleen than in the blood of the peripheral circulation but are similar in 

 appearance, though they are often a little larger and dividing forms are 

 more common. 



Microscopical examination. The technique is the same as in the case of 

 Piroplasma bigeminum. 



^Etiology. Piroplasma ovis is transmitted by the sheep tick (Rhipicephalus 

 bursa). As in other piroplasmoses it is the progeny of the ticks which have sucked 

 the blood of infected animals which transmit the disease. These daughter ticks 

 are only capable of inoculating the parasite when they have reached maturity 

 (Motas). As a rule one attack confers immunity. 



3. Piroplasma canis. 



Canine piroplasmosis is a common disease in France (Leblanc, Nocard) : 

 it occurs also in Senegal (Marchoux), in South Africa (Theiler : malignant 

 jaundice, biliary fever of dogs), in Tonkin (Mathis), in Japan (Kinositha), 

 etc. 



^Etiology. Canine piroplasmosis is propagated by dog ticks [(H cemapJiysalis 

 leachi in Africa : Rhipicephalus sanguineus in India) ] (Nuttall, Lounsbury). The 

 disease is transmitted by the offspring of those ticks which have sucked the blood of 

 infected animals but only when the daughter ticks are full-grown. A first attack 



