686 MICROBIOLOGY OF THE DISEASES OF MAN AND ANIMALS. 



drained, or covered with a film of coal oil so as to make it impossible for 

 the mosquitoes to breed in them. Those who live in a malarious district 

 should protect themselves from mosquito bites by the careful use of 

 mosquito-netting. By the simple observance of these evident indications, 

 malaria has already been banished from several localities in which it was 

 formerly endemic. 



BABESIA. 



This order is often called PIROPLASMA. It includes several parasites, which 

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

 dogs; none of them infect man. One of the best known species is Babesia 

 bigemina, which causes Red- water of cattle. The parasites which are associated 

 with the numerous babesioses 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. 



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

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

 Texas cattle fever. It is caused by Babesia bigemina (Fig. 128). The 

 parasite is transmitted by the bites of a tick, in North America, by Rhi- 

 picephalus annulatus. 



Red water occurs almost everywhere in the tropics and in many of 

 the warmer parts of the temperate zones; it is frequently seen in the 

 southern portion of the United States. 



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

 measures from 2/t to 4/1 in length and about i/x in breadth. In fresh preparations they 

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

 tions they are seen to consist of a blue-staining cytoplasm which contains a mass of chro- 

 matin 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; they are much more numerous in the 

 organs and particularly in the spleen. The disease can be transmitted, experimentally, 

 from bovine to bovine by the inoculation 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. 



