M.
ABDUSSALAM
19
quent A. pullorum in its blood.* Both these
chickens were kept in a tick-free cage
and their blood examined daily.
On 8, 9 June both the chickens were noticed
to be somnolent, their temperature had
risen to 109.2º F. and 108.4º P. respec-
tively, and their blood showed frequent
spirochaetes. The erythrocytes showed no
A. pullorum, but 'Coles' haematozoa' were
present in small numbers. After this, the
chickens could not be examined until 12
June when they were found to be brighter
and feeding well, their temperatures being
106.0º F. and 105.8º F. respectively. They
had, however, become markedly emaciated
and their combs were very pale. Blood
examination showed neither spirochaetes
nor Aegyptianella. They were considered
to have recovered from the primary attack
of spirochaetosis.
On 16 June (i. e. 14 days after the first
batch of ticks had fed) the blood of both
the chickens showed frequent A. pullorum
with 'Coles' haematozoa' as before. A
week later, A. pullorum became numerous
in each field and continued to persist in
large numbers until death. Symptoms
and blood changes associated with this
infection are mentioned below. The
chickens in the flock, from which these two
were taken, remained clinically healthy
during this period and also during the
rest of that summer.
The foregoing results are liable to be
regarded as having failed to establish
conclusively that A. pullorum was trans-
mitted by A. persicus, inasmuch as the
cage, in which the experimental chickens
were kept, was not proof against other
biting arthropods (e.g. mosquitoes) whilst,
as already mentioned, one of the chickens
had, in addition, received an injection of
infected blood. However, in view of the
experience of previous workers [Bedford
and Coles, 1933] and the appearance of
A. pullorum in peripheral blood after the
lapse of an incubation period of 14 days, it
seems highly probable that tick bites were
the source of infection in these chickens.
* Subsequent observantions showed that this injection
did not have any effect on the course of the disease in this
chicken as compared to its companion.
Bedford and Coles [1933] have experi-
mentally established that Argas persicus
can transmit aegyptianellosis to healthy
fowls with an incubation period of 12 to
15 days and that the ticks may remain
infective for at least 162 days.
The presence of Coles' haematozoon in
fowls living in tick-free fowl houses
apparently shows that it is transmitted by
an agent other than Argas. Coles [1937]
also recorded this parasite from the vici-
nity of New York where, according to him,
Argas was not likely to occur.
SYMPTOMS AND BLOOD CHANGES
It will be seen from what is stated
above that piroplasms (A. pullorum and
Coles' haematozoon) do not, as a rule, set
up any appreciable symptoms in adult
indigenous fowls or adult fowls of the
White Leghorn breed which had lived for
several generations in India. In the blood
of these adult birds the piroplasms exist
in small numbers. In the case of one bird
an attack of natural spirochaetosis did not
resuscitate the piroplasms; this disease
was, however, treated quite soon after its
appearance in the bird.
In the case of two six weeks' old White
Leghorn chickens which showed A. pullo-
rum following tick bites, clinical symptoms
associated with the infection were studied.
Both these birds first suffered from a
mild attack of spirochaetosis which they
survived without any treatment. A. pull)-
rum first appeared in their blood 14 days
after the first bites of infected ticks. At
this time the only symptoms noticed were
slight dullness and anorexia. Blood exa-
mination at this stage revealed 43 per cent
of erythrocytes to be infected. A week
later, sleepiness, dullness, emaciation and
anaemia became well marked and the
appetite capricious. The comb was quite
blanched and the blood when drawn out
of a needle prick was noticed to be dis-
tinctly watery. Body temperature showed
a constant rise by 1.0º F. or so. Micros-
copic examination of blood revealed a
heavy infestation of the red blood cells
(60 per cent) with merozoits, small and