MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 84I 



the progeny of ticks which have fed upon infected mammals, susceptible 

 cattle may be protected from the disease by preventing young ticks 

 from reaching them. This may be done by not allowing them to feed 

 over fields where ticks may have been dropped until sufficient time, 

 about ten months, has elapsed for all the ticks and their progeny to 

 have died of starvation. 



There are a number of parasites which although closely related to the 

 Babesias are usually placed in other genera. Most of these have been 

 shown to be transmitted by ticks of various species. 



East Coast Fever 



Lympho-hamocytozoon parvum — Meyer (Theiler, 1903) 

 Syn.: Theilerio parvum 



The parasite causing this disease which is characterized by severe 

 anaemia is found in the red blood corpuscles of infected cattle. ^ The 

 intracorpuscular forms vary in form, some being slender and rod- 

 shaped, the others being more rounded or pear-shaped. They may be 

 arranged to form a cross, but this is not due to segmentation but to 

 fortuitous grouping in heavily infected cells. They are regarded as 

 gametocytes, for although such blood is infectious for ticks it will not 

 produce infection when injected into normal cattle. The multipli- 

 cative or asexual phase of the organism is restricted to certain organs, 

 especially the lymph nodes, spleen and bone marrow. The tissue from 

 these organs when injected into normal cattle produces infection. 



Theileria {Babesia) mutans is a parasite of cattle closely resembling 

 T. parvum since it furnishes many rod-shaped forms in the red blood 

 corpuscles. The cross-forms which occur in this species result from 

 segmentation and since the blood is infectious when injected into normal 

 animals it is evident that the asexual phase is present in the blood. 

 This parasite produces no serious symptoms and does not appear to 

 afifect the health of the animal. 



Oroya Fever 

 Bartonella bacilliformis — Strong, Tyzzer and Sellards, 191 5 



A human disease characterized by rapidly developing and severe 

 anaemia associated with an irregular fever occurs in certain mountain 

 valleys in Peru. The red blood corpuscles harbor slender rod-shaped 



