286 



THE PIROPLASM-^SIDA 



cause piroplasmosis or babesiosis, a 

 group of highly fatal and economically im- 

 portant diseases of livestock. Other gen- 

 era are Echinozoon and Aegyptianella. 



Genus BABESIA Starcovici, 1893 



For practical purposes, one can divide 

 the genus into 2 groups of species, large 

 forms more than 3|i long and small forms 

 less than 3(i long. In general, infections 

 with the large forms can be successfully 

 treated with trypan blue, while infections 

 with the small ones cannot. 



In this genus the trophozoites multiply 

 by binary fission in the erythrocytes, 

 forming pairs, or by schizogony, forming 

 tetrads. A "blepharoplast" from which a 

 rhizoplast arises has been described in 

 the trophozoites. However, Rudzinska 

 and Trager (1960) did not report seeing 

 either of these structures in electron 

 micrographs of Babesia rodhaini irom the 

 mouse. 



If present, the blepharoplast and 

 rhizoplast may betray a flagellate origin 

 for the group (Dennis, 1932). However, 

 Reichenow (1953) thought that it originated 

 from the amoebae. Another possibility is 

 that it is related to PlasniocUiim. This is 

 suggested by Rudzinska and Trager's (1960) 

 finding in B. rodhaini of structures com- 

 posed of concentric membranes (possibly 

 representing primitive mitochondria) 

 similar to those they had previously seen 

 in Plas)>iodimii berghei, and by their ob- 

 servation that B. rodhaini apparently en- 

 gulfs bits of host cell cytoplasm by phago- 

 trophy like Plasmodium . 



There are two opposing schools of 

 thought as to the speciation of this genus. 

 One breaks it up into several genera or 

 subgenera, each with a number of species 

 (e. g. , Sergent et al. , 1945; Antipin el al. , 

 1959), while the other prefers a single 

 genus with a relatively small number of 

 species, each of which may include sev- 

 eral strains (e.g., Wenyon, 1926; Neitz, 

 1956). The second system seems prefer- 

 able. The taxonomy of the group has been 

 discussed by Reichenow (1953), Poisson 

 (1953) and Laird and Lari (1957) in addi- 

 tion to the above authors. 



Synonyms of Babesia include Piro- 

 plasma, Achro)>ialiciis, Nicollia, Niittal- 

 lia, Smithia, Rossiella, Microbabesia, 

 Babesiella, Francaiella, Lnlisia, Patton- 

 ella, Rangelia, and Gonderiain part. 



Babesia and babesiosis occur in most 

 parts of the world where there are ticks, 

 except in countries such as the United 

 States where they have been wiped out by 

 a concerted effort. They are most impor- 

 tant in the tropics, where, along with the 

 trypanosomoses, they often dominate the 

 livestock disease picture. However, they 

 also occur in the temperate zone. Bovine 

 babesiosis nearly reaches the Artie circle 

 in Norway, and Thambs-Lyche (1943) re- 

 ported that it was increasing in that coun- 

 try. 



Babesiosis was once an extremely 

 important disease of cattle in the United 

 States, but it has now been eliminated, 

 and the only domestic animal species left 

 in this country is B. canis, which occurs 

 in dogs in Florida, Virginia and Texas. 

 However, Babesia is still important in 

 livestock in Central and South America. 

 It occurs in most of Europe, being espe- 

 cially important in the countries bordering 

 the Mediterranean Ocean. It is one of the 

 most important diseases of livestock in 

 the Middle East, thruout Africa, and also 

 in parts of India and the Far East. Its 

 importance in the USSR, and especially in 

 its southern part, is attested by the fact 

 that 61 X of the protozoan section of Antipin 

 el al. 's (1959) textbook on veterinary para- 

 sitology is devoted to it and a related dis- 

 ease, theileriosis. It also occurs in Aus- 

 tralia. 



Veterinarians and livestock owners 

 in the United States today do not know 

 what it is to have to contend with babesi- 

 osis, but other parts of the world are not 

 so fortunate. The disease is of great ec- 

 onomic importance in the tropics and sub- 

 tropics; indeed, Curasson (1943) believed 

 that it was no exaggeration to say that the 

 babesioses are the most formidable dis- 

 eases of livestock in these regions and 

 that they are taking a more and more 



