Symptoms, Prevention. 781 



Symptoms. The incubation period is 10 to 12 days (Tlieiler, 

 Kleine), visible symptoms however appear usually only 20 days 

 after the time of exposure in infected pastures. These con- 

 sist in high fever, difficult respiration sometimes associated with 

 a cough, salivation, passing of very dry or bloody, tar-like 

 feces, marked swelling of the submaxillary lymph glands, 

 emaciation and weakness of the hind quarters. Contrary to 

 Texas fever the appetite remains normal for a long time, and 

 anemia, icterus and hemoglobinuria are only seldom observed. 

 At the height of the fever parasites may be demonstrated in 

 the red blood corpuscles, sometimes infesting 80 to 90%. At 

 the same time the destruction of blood corpuscles is only 

 slightly evident. Cattle infected with Piroplasma bigeminum 

 may later become affected with coast fever, in which case the 

 symptoms of Texas fever are also pronounced, and the para- 

 sites of both diseases may be found side by side in the blood. 



The disease is very destructive, as in previously non- 

 infected herds 95% of the animals die, whereas in native cattle 

 on the coast of East Africa deaths are rare. 



Prevention. The infection may be kept at least temporarily 

 from healthy herds by the careful segregation of suspected 

 or affected animals (fenced in!). Dipping and spraying for 

 the destruction of ticks, after fresh outbreaks, and driving the 

 cattle into non-infected fields are advantageous preventive 

 measures. In severely infected pastures the ticks may be in- 

 fectious even after eight months, and even when there have 

 been no cattle pastured there in the meantime. The danger 

 of the pasture is eliminated after 15% months, if during that 

 time it is pastured only by horses, goats or sheep. 



Immunization. (Koch). Animals which, have recovered from the 

 disease are protected against a second attack even if remaining in an 

 infected pasture, repeated injections of blood containing the parasites 

 likewise produce a lasting immunity. For this purpose cattle are in- 

 jected subcutaneously at two weeks intervals for 4-5 months with 5 ce. 

 of defibrinated blood from cattle, which have recovered from a severe 

 attack of the disease. Cattle treated in this manner remain healthy in 

 infected pastures, and even their offspring are supposed to resist a later 

 infection after they have recovered from a mild form of the disease. 



Theiler & Stocltnian failed to obtain favorable results from Koch's method, 

 arid the conference of South African veterinarians, held in Cape City in 1907, also 

 denied its practical value. According to Gray the method has been employed in 

 the Victoria District on 5,700 cattle without any results, as the animals became 

 spontaneously infected, even after U to 12 inoculations. 



Cattle which have recovered from Texas fever are immune against the coast 

 fever, while animals which have recovered from the latter are not immune against 

 Texas fever. 



Literature. Koch, A. f. Tk., 1904. XXX. 281 u. 586; D. med. W., 1905. 

 1867. — Theiler, Fortschr. d. V.-Hyg., 1903. I. 133; 1905. II. 256; J. of the Eoy. 

 Army Med. Corps, 1904; Oomp. Path., 1907. XX. 1; 1909. XX. 115; Eep. of the 

 Gov.-Bact., 1906-1908. -^ Theiler & Stockman, Comp. Path., 1904. XVII. 3. — 

 Gray, ibid., page 203. — Kleine, D. med. W., 1905. 912. ^ Collaud, Diss. Zurich 

 1906. — Soulie & Eoig, C. E., 1908. CXLVII. 192. — Lichtenheld, A. f. Hyg., 

 1908. LXI. 261; 1910. LXV. 378. — Meyer, Comp. Path., 1909. XXII. 213. 



