146 Journal op the DBi*ARTMfiNf oP Agriculture. 



days and averag-es about thirteen days. The disease, whicli is 

 characterized by high fever, lasts from six to about twenty days, and 

 averag-es about twelve days, hence an animal may die as soon as twelve 

 days or as late as thirty-seven days after it was bitten by ticks, the 

 usual period being- about twenty-five days. A typical syrnptom of 

 this disease is the enlargement of all lymphatic glands which stand 

 out markedly, loss of condition may be rapid, and in the dead animal 

 froth is frequently exuded from the nostrils. 



Heartwater in Cattle, Sheep, ind Goats. 



This is a disease caused by a non-visible organism. We prove its 

 existence by the inoculation of the blood of a tiick into a susceptible 

 animal, which promptly produces the disease. The action of the 

 parasite must be interpreted as an intoxication, as a result of wliJcli 

 the animal may die. 



The disease is tick-transmitted, as Lounsbury first proved. The 

 experiments undertaken for this purpose have shown that the bont 

 ticks {Ainhlyoiiima hebraeum) play an active role in the propagation 

 of it, but only when they have been sucking Hood from an animal 

 suffering from the disease and not from an immune animal. The 

 incubation period varies from five to fifteen days in goats and about 

 twenty to twenty-five days in cattle. It is of special interest to us 

 that immune animals do not retain the virus in their blood. 



Biliary Fever in Dogs. 



This disease is caused by Babesia canis (formerly Pirojdasina 

 canis), a parasite very closely allied to Babesia higeviina, the cause 

 of ordinary redwater. Like this species it lives in and destroys the 

 red corpuscles of the blood, and so causes the jaundiced discoloration 

 and anaemic condition, frequently accompanied with brown, yellow, 

 or reddish staining of the urine. This disease, like redwater, can be 

 cured by the injection of a 1 per cent, solution of trypan blue. The 

 disease is transmitted by the dog tick (Haemaphysalis leachi), as 

 Lounsbury demonstrated. The first symptom to appear is the fever, 

 which is noted after a typical incubation period. One of the brown 

 ticks (the European brown tick) has also been found to be a carrier, 

 viz., Rh. sanguineus. In this country it is the common tick of the 

 kennels, whereas the dog tick is picked up in the veld. 



Paralysis in vSheef. 

 In the Cape Province, and also in the Orange Free State, a paralysis 

 of sheep and lambs is known to occur which is connected by farmers 

 with the presence of a tick, Ilvodes pilosus, and it is stated that after 

 removal of the tick recovery is soon effected. These statements have 

 not yet been experimentally verified and accordingly no explanation 

 as yet can be given — if the observation is correct — as to what the real 

 action of the tick would be. A priori it would look as if some toxic 

 action is produced through the bite of the tick. 



Eeservoir of Virus. 



The diseases which are tick-transmitted in South Africa may be 

 classified into two groups. The first one, in which the immune 

 animal retains the infection in the blood, in other words in which the 

 recovered animal acts as a constant reservoir for the virus, and the 

 second group where the blood of a recovered animal becomes sterile 



