THE CATTLE TICK. 
may be markedly discoloured by the presence of the pigment in a more 
or less reduced form—hence the name redwater, which is sometimes 
given to the disease. Affected animals, if adult, commonly die, but 
young beasts pass through an attack with usually comparatively slight 
symptoms. A recovered animal is not, as a rule, subject to further 
serious ‘attack, but it remains a potential source of infection, as some 
parasites persist in the blood, even for very many years. Apparently 
4 true immunity is not established, but rather a chronic state of mild 
tick fever. 
A necessary stage in the development of the parasite is passed 
through in the tick, the organisms which enter the. ox blood, passing 
from the gut to invade various organs of the tick, some entering the 
ovary, and actually parasitizing the eggs. The larvee which hatch 
from such infected eggs are infected, and it is they which are the chief 
means by which the disease is spread. Here, then, we have a case of 
- so-called hereditary infection. It is not quite a correct term, since 
some eggs may not be infected, and thus from an infected parent some 
larvee may be born infected and others not. 
As most of the cattle country in Queensland is ticky, and since the 
beasts usually pass through an attack of tick fever while young, the 
mortality being slight, tick fever is not so dreaded now, except in case 
of new stock, e.g., especially bulls brought in from “clean” country, 
‘such importations being usually “protectively inoculated” against 
piroplasmosis. 
Tick worry, or tick poverty, is much more serious, and is due to the 
combined effect of the loss of blood abstracted by the hordes of parasites, 
the irritation set up by them, and the injection into the beast of some 
detrimental substance by the tick. Gross tick infestation, like tick 
fever, leads to interference with the condition of the beast, loss of milk 
in the case of cows, anzemia, and even death. 
Errecr on ComMErcr. 
During the six years—1894 to 1900—it has been estimated that the 
mortality due to tick fever caused a direct loss of £3,500,000 sterling. 
To this must be added losses resulting from the diminution of natural 
increase. The losses due to tick fever and tick infestation at present 
are not nearly so heavy, but as they are occurring all over the cattle 
districts, they are certainly appreciable. 
The loss in condition is a very serious item, as it results, not only 
in a reduced weight and quality of beef, but also in a diminution in the 
quality and quantity of milk produced by affected cows. Such inter- 
ference with the milk supply re-acts on the dairy industry in its 
various activities, such as butter or cheese production, pig raising, &c. — 
Another serious loss is experienced in regard to the value of hides. A 
committee of the Institute of Science and Industry, of which the writer 
was a member, after obtaining expert opinion, reported in 1916 that 
the depreciation of a ticky hide varied from 03d. to 23d. per Ib. on the 
leather produced, and that the loss in Queensland in 1915 due to this 
cause alone was approximately £114,000. 
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