"228 A TICK-RESISTANT CONDITION IN CATTLE. 



Nuttali and Strickland* when referring to the toxic 

 •effects following the bites of Argas -persicus which attacks 

 man (and ])oultry), mentioned that strangers to tick- 

 infested districts suffer ni(n"e than others do, reminding 

 one of the kind of imnumity to mosquito bites experienced 

 by many people- — a form of habituation. This supported 

 the view that ticks give off something of the nature of a 

 poslon when inflicting their ])ites. 



It is a common report in Queensland that ticks, mos- 

 quitoes and even leeches will much more readily attack 

 a townsman in preference to a " bushman " when the two 

 are in company in a scrub- — ^the explanation being almost 

 certainly due to the existence of a greater or less degree of 

 immunity, probably the result of previous attacks. 



Tick Poison. 

 Tidswell (1899, p. 5) in commenting on the greater 

 virulence of piroplasma infection by ticks over infection 

 by inoculation, was led to suspect that ticks themselves 

 might have some injurious effect apart from causing tick 

 fever and that such effect was not a question of anaemia 

 caused by the amount of blood lost, since that loss is com- 

 paratively slowly brought about and the time taken would 

 permit regenerative activity of the host tissues. He 

 suggested the possibility of some poison being injected by 

 the tick and mentioned the well known effect often produced 

 in dogs in this continent by the attack of ticks belonging 

 to a certain species {Ixodes hohcyclus Neum). 



The possibility of the cattle tick injecting a poison 

 and thus setting up a toxaemia was mentioned also by 

 Hunt (1898, p. 448), by Thompson (1899, p. 742). and by 

 Hchroeder (1906, p. 59). In accounting for tick woriy 

 J. D. Stewart (1906, p. 1156) says, "In our present knowledge 

 the mechanical irritation caused by the ticks in their attach- 

 ment, the loss of blood extracted by them, and particularly 

 by the maturing females, together with the effects of toxines 

 absorbed from the sloughing wounds, might reasonably 

 be accepted as sufficient to account for the condition. 

 It is, however, possible that the tick injects a secretion when 

 it attaches itself. . . . " 



♦Nuttali and Strickland, Paraaitol., 1, 1908, p. 302. 



