338 ACUTE GENERAL INFECTIOUS DISEASES 



not infrequently fibrinous exudation. The lungs are edema- 

 tous, the spleen is normal and the liver and kidneys congested 

 or inflamed. The superficial lymph glands are enlarged. 



Symptoms. — The period of incubation is about one week. _ 

 Four forms of the disease are described from a clinical stand- 

 point: The peracute, acute, subacute, and chronic. The most 

 important are the acute and subacute forms. 



(a) Acute Form. — This form, known in Africa as Dunko- 

 pziekte, begins with a high fever (104° to 107.6° F.), dyspnea, 

 pulmonary edema, and heart paralysis. Death usually occurs 

 in one or two weeks. 



(b) Subacute Form. — The subacute form, known as Dikko- 

 pziekte, takes a longer and milder course. Characteristic of 

 this form is a marked swelling of the head, principally about 

 the eyes; swelling and prolapses of the tongue which is 

 markedly cyanotic. From this symptom the name Blaw 

 tong (blue tongue) is given the disease. The patient shows 

 marked muscular weakness. In this form the majority of 

 the cases recover. 



The peracute or apoplectic form produces sudden death; 

 the chronic form assumes an atypical course lasting for weeks 

 and resembling infectious anemia. 



Treatment. — A medicinal treatment has to date not proven 

 satisfactory. Internally large doses of creolin have been 

 recommended. 



Prevention. — Prevention consists in keeping the horses off 

 infected or suspected pastures during the night time or driv- 

 ing them to higher altitudes during the dangerous months 

 of the year. Fairly good results have been obtained by pre- 

 ventive inoculation to produce immunity. As in hog cholera 

 a combined virus and serum vaccination is practised. 



Heartwater. — Definition. — Heartwater is a disease which is 

 not identical with horse-sickness. It is a contagio-infectious 

 hydropericardium of cattle, sheep and goats of the Transvaal, 

 The disease is carried by ticks ( Amblyomma hebrseum) . 



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