TO SOME DISEASES OF STOCK 
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It has also been shown that even though these larvae 
feed upon a horse or other animal which is not susceptible 
to the bovine Kedwater parasite, and reaching maturity 
eventually give rise to a second generation of larvae, these, 
too, are still infective and capable of giving rise to the disease. 
Infection then passes through the egg. 
The parasite of dog-tick fever ( Piroplasma canis) also passes 
through the egg, having been acquired by the adult female 
feeding upon a parasite-containing dog ; but in this case the 
infection is not given to the dog upon which the larvae feed, 
nor to that on which the nymphs feed. The infection lies 
dormant through these two stages, and is only transmitted 
by the bite of the young adult tick. 
In East Coast fever the infection is acquired at the larval 
feed and conveyed as a nymph ; or acquired as a nymph and 
given as an adult. The parasite cannot lie dormant through 
the nymphal stage, nor does it pass through the egg. 
Biliary fever of the horse is acquired during the larval or 
nymphal stage, which in the case of Bh. evertsi are passed on 
the same host, and given by the young adult. 
Heartwater infection is acquired at either the larval or the 
nymphal stage, and given at the succeeding one, as is the case 
with East Coast fever : but here the infection may lie dormant 
through the nymphal stage should this be passed on an un- 
susceptible animal, and be transmitted as an adult. It does 
not pass through the egg. 
Gastro-enteritis in sheep can be transmitted by an adult 
Bh. appendiculatus, the brown-tick, which fed as a nymph on 
a sick sheep. Up to now, we have been unable to incriminate 
any other stages. 
In addition to the above-mentioned ticks there are four 
other species fairly common in certain parts of the Protectorate, 
which we have not yet been able to rear successfully under 
experimental conditions, and they have, therefore, not yet 
been proved carriers of any disease. But there is no doubt 
that subsequent research will show them capable of transmitting 
some infection either known or new. 
The importance of being able to breed and rear ticks is 
obvious in view of what was said regarding their destruction 
