‘of the infective agent. 
eth oe ew RRA RES 
April, 1910 
29 
THE AUSTRALIAN GARDENER. ~ 
2 
“= Fhe P 
. Tick Fever in Fowls. 
A. A. Brown, M.B., BS., Inspector of 
Foods for Export. 
A disease that is the cause of con- 
siderable mortality in fowls, and conse- 
quently of to poultry 
breeders, prevails over a large extent of 
Australia. It 
estimate the losses anpually inflicted 
on the poultry industry in the Common- 
‘great losses 
wealth by the depredations occasioned by’ 
the fowl tick (Argas americanus) that is 
the primary factor in the dissemination 
agent is a micro-organism which belongs 
to the protozoa, or lowest division of the 
animal kingdom. It is harboured in the 
bodies of Argasides or fowl ticks, and the 
‘ticks by biting fowls -introduce it into 
their bodies. 
"Dick fever is a disease of the blood in 
which hemolysis, or destruction of the 
red blood corpuscles, is & characteristic 
feature, and this haemolysis is “produced 
by the vital activities of the micro- 
parasite. . 
Fowl tick does not mature on the 
‘bodies of horses, cattle, sheep, pigs, dogs, 
ducks, or geese, although ticks may 
puliry Yard: ¢ 3 
them. 
would be difficult to’ 
The infective 
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occasionally perhaps be observed on 
The special 
prevailing in the Argus americanus that 
micro-organism 
causes the fever in fowis has not, more- 
over, ever yet been detected in the blood 
of any animal or ‘bird in the orders 
mentioned, 
Ticks attack birds belonging to the 
pigeon and fowl tribes and young ticks 
attach themselves to their bodies, and 
there they may remain until they undergo 
certain transformations 
their development. 
There is as yet no direct evidence to 
prove that chickens hatched from the 
eggs of fowls that had suffered, and yet 
recovered from tick fever, are hereditarily, 
immune. Young chickens in the infested 
areas are probably often attacked and 
inoculated by ticks so that by the time 
they have reached the adult stage of 
existence, provided they have survived 
the inoculations, they have acquired 
immunity to the specific micro-organisms. 
Ticks can be kept in receptacles that 
admit air without food for twelve months 
without losing their vitality. 
The micro-parasite, the Piroplasma 
gallince, which is the actual cause of the 
fever in fowls: suffering from tick fever, 
is a particularly small motile organism 
belonging to the animal kingdom. The 
incidental to’ 
organisms exist both in the ‘blood’cells 
(intra-corpuscular forms) ‘and in tle 
blood serum (extra-corpuscular forms). 
The extra-corpuscular forms are far more’ 
numerous and larger than the intra- 
corpu cular forms. In preparations 
made from the blood of the heart and 
jarge vessels only a few organisms are at 
any time detectible, but in ‘preparations 
made from the blood of capilliaries of 
internal organs, particularly the kidneys,” 
many of the protozoans may readily be- 
seen, The red blood cells of the fowl are 
about }-2000th of an inch in length, and 
the piroplasma is from 1-ldth to 1-20th 
the size of a red corpuscle. The intra 
cellular forms may be detected in the 
cover slip preparations, hence the 
difficulty experienced in deternining the’ 
exact causation of the mortality in tick 
infestation. The extra-cellular forms are’ 
larger and more numerous than the intra’ 
cellular forms, and in preparations of 
blood from fowls freshly killed they are 
readily enough observable’ to the trained 
observer. 
The body temperature of affected 
fowls rises several degrees. ‘The normal: 
temperature of a fowl is 107’ degrees, but 
elevations of the temperature to 110 and 
even 112 degrees are not uncommon in 
the course of tick fever infection. The 
fowls become weak, emaciated, and lose 
the power of their legs. The red blood 
corpuscles are broken this 
condition is one of the essential factors 
in the course of the disorder. Since the 
organisms belong to the protozoa they 
are incapable of being cultivated outside 
the bodies of fowls. 
The organisms, besides varying in size 
vary also in form. Some are spherical, 
some pear shaped, some oblong, and some 
possess irregular shapes. They are highly 
refractive and do not satisfactorily absorb 
However, they can be stained by. 
up and 
stains. 
special methods and I possess some very 
good slides. nce 1 
reported the existence of the Piroplasma 
gallince in the blood of fowls and its 
It is some time since L 
connection with the tick “fever disease. 
Quite recently again, for further investi- 
gation, I sent two young fowle to Swan 
Hill to be-placed in a situation where 
they might become tick infested and so 
