MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 839 



Babesia (Starcovici, 1893) 



This order is often called piroplasma. It includes several species of parasites, 

 which cause diseases of considerable economic importance in horses, cattle, sheep, and 

 dogs. One of the best-known species is Babesia bigemina, which causes Red- Water 

 or Texas Fever of cattle. The parasites which are associated with the numerous 

 babesiases are distinguished from one another by the host in which they are found, 

 by slight differences in their morphology and by their inoculability into various 

 animals. 



Red Water 

 Babesia bigemina — Smith and Kilborne, 1893 



Red water is one of the names given to a disease of cattle which is 

 characterized by hasmoglobinuria; in the United States it is often called 

 Texas cattle fever. It is caused by Babesia bovis (bigemina) (Fig. 

 180). The parasite is transmitted by the bites of a tick, in North 

 America, by Rhipicephalus annulatus. 



Red water occurs not only in the southern portion of the United 

 States but almost everywhere in the tropics and in many of the warmer 

 parts of the temperate zones. 



The parasite is a pear-shaped organism which usually lies within a red cell. It 

 measures from 211 to 4m in length and about iai in breadth. In fresh preparations 

 they appear as refractile bodies possessed of slight amoeboid movement; in stained 

 preparations they are seen to consist of a blue-staining cytoplasm which contains- a 

 mass of chromatin at its broader end. Multiplication is accomplished by simple 

 division into two or more parts; it is possible that schizogony and sporogony may 

 also occur. The parasites are often very scarce in the peripheral circulation 

 but are much more numerous in the organs and particularly in the spleen. The 

 disease can be transmitted, experimentally, from bovine to bovine by the inocula- 

 tion of blood which contains parasites; normally, it is transferred from animal 

 to animal by the bites of a tick. The species of tick which carries red water is not 

 the same in all parts of the world. 



Ten days intervene between the bite of the infecting tick and the 

 first sign of the infection. The temperature rises, it may be, to 106°, 

 or more, and it remains high for a week. The animal is evidently very 

 ill, it has no appetite, and it rapidly loses strength and weight. Many 

 red cells are destroyed and anaemia may be marked. The urine is 

 albuminous and it is red because of the haemoglobin which it contains. 

 Death may occur in very acute cases as early as the second day. 

 Animals which recover from a severe attack are usually immune to the 



