PIROPLASMOSES 447 



stable-fed cattle are occasionally infected. Cows and year- 

 lings are most susceptible. The disease also attacks sheep 

 and goats. Badly tick-infested pastures are permanent 

 sources of infection, particularly wet woods pastures and 

 boggy fields which adjoin brush and timber lands. Native 

 calves, are more resistant than adults and native cattle with- 

 stand the attack better than imported animals. One attack 

 does not produce permanent immunity, as the same animals 

 may repeatedly suffer from the disorder. 



Etiology. — The cause of "the disease is the protozoon 

 Piroplasma bigeminum, which is transmitted by the European 

 cattle tick, the Ixodes ricinus (I. redubius), which is harbored 

 in grass, brush, bushes, etc., especially on low swampy lands. 

 The life history of this tick is somewhat different from that of 

 the American cattle tick. The female does not lay so many 

 eggs and the hatching period is longer (six weeks). The 

 larvae leave the cattle three to five days after attaching 

 themselves to the skin and on the ground develop into 

 nymphs in about four weeks. They then reattach them- 

 selves to the skin of an animal, remain three to five days, 

 drop to the ground and in the following eight weeks develop 

 to sexually mature ticks which again attach themselves to a 

 host, suck its blood and copulate. Therefore the larvae, 

 nypmhs and sexually developed ticks are capable of carrying 

 the infection. The time which lapses between the laving of 

 the eggs and the dropping off of the pregnant female is 

 about nineteen weeks under average conditions. 



Symptoms.— The period of incubation is ten days. The 

 first symptoms are high fever (J 06° F.), which is soon followed 

 by diarrhea. About the second day the characteristic hemo- 

 globinuria, appears and the urine becomes red. The shade 

 of red may vary from a light claret-wine to a dark tar-like 

 color. The patient rapidly becomes anemic and the mucous 

 membranes icteric. In some cases there is marked weakness 

 of the hindquarters. The blood of the animal is thin, very 

 dark colored, and its serum is stained red (hemoglobinemia) . 

 Microscopically (blood drawn from an ear vein), pear-shaped, 

 round or rod-shaped protozoa are seen in the red corpuscles 

 with proper staining. 



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