TICKS AND DISEASE 569 



experiment that the cattle disease known as ' Texas Fever ' is transmitted 

 by a species of tick, Margaropus annulatus, Say, which they found on the 

 sick animals. A considerable number of similar diseases are now known 

 to affect other useful animals, such as the horse, mule, donkey and the 

 dog ; in the majority of instances the piroplasms which cause the diseases 

 have been shown to be transmitted by different species of ticks. 



The piroplasm of cattle, Piroplasma bigeminum, the cause of ' Texas 

 Fever ' in America, is common in tropical and subtropical regions. In 

 the United States the parasite is transmitted by Margaropus annulatus, 

 and in South Africa by Rhipicephalus capensis, Koch, C. L. In Europe, 

 Ixodes ricinits is the probable transmitter, while in England Haema- 

 physalis pttnctata, Can. and Fan., has been experimentally proved by 

 Stockman to be the carrier of this piroplasm. In South India the 

 senior author has transmitted Piroplasma bigeminum to calves by Mar- 

 garopus annulatus. In South America, Cuba, Porto Rico and the 

 Philippine Islands Margaropus annulatus, variety australis, Fuller, is 

 the carrier. 



Theileria parva, a small species of piroplasm which is the cause of the cat- 

 tle disease known as ' Rhodesian Fever,' is transmitted by Rhipicephalus 

 appendiculatus, Neum. Theiler has recently shown that a new parasite of 

 the red blood cells of cattle, which he names Anaplasma marginale, is 

 transmitted by Margaropus annulatus variety decoloratus, Koch, C. L. 



Dogs of all kinds and in many parts of the world are commonly 

 attacked by a species of "piroplasm, P. canis, which in South Africa is 

 transmitted by Haeinaphysalis leachi, Audoin, in India by Rhipicephalus 

 sanguineus, Latr., and in Europe probably by Ixodes ricinus, L., and 

 Dermacentor reticulatus, Fabr. 



In South India the jackal is naturally infected with another species of 

 piroplasm, P. gibsoni, which is probably also transmitted by a tick, 

 though the effective species has not yet been determined ; this parasite is 

 exceptional in that it is not restricted to one vertebrate host but can 

 be transmitted to the dog ; it causes serious epidemics among the 

 hounds of the Madras Hunt. 



The disease of horses, mules and donkeys known as ' Biliary Fever ' 

 is caused by one or more species of Piroplasmata ; in South Africa one of 

 these parasites, P. equi, is carried by Rhipicephalus evertsi, Neum., and in 

 Russia by Dermacentor reticulatus. In Europe Piroplasma ovis, the cause 

 of ' Redwater ' in sheep, is transmitted by Rhipicephalus bursa, Can. and 

 Fan. In South Africa goats and sheep are known to suffer from a fatal 

 disease called ' Heart water ' and although the parasite is unknown, it 



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