1909.] Texas-fever or Red-water in Cattle. 397 



cides with the tropical piroplasmosis in being inoculable, the 

 only difference in this respect which could be discovered being 

 that the blood of animals recovered from English Red-water 

 did not appear to be potentially infective for so long a time 

 as in the case of the tropical form of the disease. This differ- 

 ence, however, cannot be looked upon as very material, 

 although it is important enough in considering measures of 

 prevention in relation to the former. 



Transmission of the Disease by Ticks. — Having established 

 the inoculability of the English disease, the natural method of 

 infection had to be inquired into, because, as in the case of 

 Texas-fever, cattle affected with Red-water may stand 

 alongside healthy animals without transmitting., the infec- 

 tion. Naturally, the probability of the English disease being 

 tick-borne suggested itself, and this involved an inquiry into 

 the distribution of ticks in Great Britain, the life-history of 

 the varieties of ticks found on Red-water farms, and the 

 seasons of the year during which they are most prevalent. 

 This part of the inquiry is not yet completed, but a great deal 

 of information on the subject has been obtained. 



Only two varieties of ticks, the Ixodes ricinus and the 

 II cemaphy sails punctata, with a similar life-history, have been 

 collected from cattle and sheep in the field, and both varieties 

 have in certain cases been obtained from farms where Red- 

 water is known to exist. It seems practically certain that both 

 are capable of carrying the parasites which cause Red-water, 

 although experimental proof has up to date only been ob- 

 tained as regards one of them, the Hcemaphysalis punctata. 



Methods of Infection. — A consideration of the life history 

 of these ticks suggested that they might be infective in several 

 stages, and an investigation was therefore conducted at the 

 laboratory into this point. As a result of this inquiry, which 

 is described in the Report, the conclusion was arrived at that 

 the Red-water of this country is spread under natural condi- 

 tions from animal to animal by ticks. It must not be thought, 

 however, that the mere presence of ticks on pastures means 

 that cattle put to graze thereon will contract Red-water. The 

 ticks of themselves are harmless, and remain so until they have 

 fed upon an animal sick or recovered from piroplasmosis. 

 There are plenty of farms which are infested with ticks, but 



