104 



farmers do not exhibit at southern stock shows. In fact, the losses in 

 these and other directions are so great that they could be borne by no 

 other cattle-raising section of the country except the south, whose 

 excellent pastures, rich soil and healthy climate enable it to over- 

 come such obstacles in meeting the competition of the west. These 

 losses can all be entirely effaced at a small proportional cost. 



Under natural conditions the disease appears in 13-90 days after 

 exposure. After the seed ticks become attached to the animal, the 

 disease will manifest itself in about 10 days in summer. Artificial 

 inoculation of a cow with virulent blood under the skin or into a vein, 

 produces the fever in from 3 to 10 days. The author gives full clinical 

 details of the disease in its acute and chronic types and relapses, and 

 also postmortem conditions. The mortality varies considerably ; 

 in adult susceptible animals it ranges from 90 per cent, in summer 

 to 50 per cent, in winter. In animals under 9 months the course of 

 Between 1 J-2 years the mortality is about double that at 1 year, 

 the disease is usually short and rarely fatal, while among one-year-olds, 

 during hot seasons, it is 25 per cent., and in cold seasons 10 per cent. 



It has been proved by experiments made at the Bureau of Animal 

 Industry that the disease can be carried by three known methods 

 only: — (1) By the bite of the fever tick; (2) by inoculating the 

 blood of sick animals ; (3) by inoculating the infected blood of appar- 

 ently healthy southern cattle into non-immune cattle. The digestive 

 tract was shown to be proof against infection. After numerous 

 experiments on various species of animals with highly virulent blood 

 Texas fever has been produced in bovines only. Horses, asses, sheep, 

 pigs, dogs, cats, mice, rats, guinea-pigs, rabbits, chickens and pigeons 

 are among those w^iich gave negative results. All bovine animals 

 that have never been exposed to the disease are susceptible, although 

 sucking calves are markedly resistant ; under 8 months they contract 

 the affection in a mild form and as a result become immune. 



Under the heading of prevention, the author remarks that as 

 BoopJiilus anmdatus infests pastures only transiently, never per- 

 manently, and will not mature except upon cattle or equines, its 

 extermination is quite feasible. For details of methods, reference 

 is made to Farmers' Bull. No. 498, " Methods of Exterminating the 

 Texas fever Tick." Full information is given as to methods of immun- 

 isation, artificial blood-inoculation being considered much more 

 accurate than seed tick inoculation. 



At one time the tick-infested area w^as rapidly spreading northward, 

 but since the adoption of a quarantine line and the enforcement of 

 rational regulations, it has gradually been moved further south. 

 The education of cattle-owners as to the nature of tick fever and the 

 method of its transmission is an important step, and several cattle 

 clubs have been organised with success for this purpose in some 

 infected districts. In counties of Virginia, North Carolina and Georgia, 

 where the laws compel fencing of pastures, the tick in question soon 

 disappeared, and such tick-free counties were placed above the quar- 

 antine line without any loss of cattle in these districts. Co-operation 

 and uniform legislation should be secured in all infected States. The 

 author considers that by the general application of adequate control 

 measures, the fever tick could be eradicated in a comparatively short 

 time, and that the cost of such measures would be far less than the 

 sum saved in the first year after the ticks had been exterminated. 



