S. N.
SAPRE
153
through the donor's excreta. Secondly, to obtain
an enduring and comparatively high level of bac-
tereamia in the peripheral circulation, such as
would be essential for assuring infection through
a transmitting agent, is difficult with buffaloes.
Rabbits however are suitable animals since they
can be easily housed and handled, and when they
are kept in glass containers, the infected fleas
can easily be collected after death of the donor.
Since the housing arrangements for the donor
and receptor are separate, the possibility of in-
fection through infective excreta of the donor
can be easily avoided.
The 11 experiments carried out may be con-
veniently divided into three groups. All buffaloes
were under one year of age.
Group I (One experiment). In this an attempt
was made to transmit pasteurollosis from one
buffalo calf to another. The donor, however,
failed to show Pasteurella in the peripheral cir-
culation till death. Neverthless when a rise
in temperature (2ºF.) was observed, 400 fleas
were liberated and left till death of the animal.
Fleas collected from the dead animal were negative
bacteriologically. The receptor failed to show
definite infection although it was left in the closed
room used for the experiment and which presum-
ably still contained infected fleas hiding in cre-
vices, debris, etc. Discharges and other contam-
inated articles only were removed and no attempt
was made at disinfection. This experiment cannot
be considered satisfactory, since for an unknown
reason, the receptor died 15 days after exposure
to the fleas. A careful cultural examination of
its bone-marrow gave negative results.
Group II (Three experiments). Rabbits were
used as donors and buffalo-calves as receptors.
About 500 fleas were used in each of the three
experiments. They were liberated on the donors
when a rise of temperature of 2ºF. had occurred.
The Pasteurella-infected fleas, after fasting for
one-and-a-half to two hours, were fed on the recep-
tors (one buffalo in each experiment) for one
hour on a closely clipped circumscribed area of
skin under a funnel and then finally liberated.
Fleas collected from the receptor buffaloes on the
following day were shown to contain Pasteurella.
None of the three receptor buffaloes showed clinical
symptoms and were liberated from the experiment
a fortnight later.
Group III (Seven experiments). The number of
fleas used in the experiments were 808, 1,600,
1,600, 160, 2,000, 340 and 3,000 respectively. As
soon as Pasteurella were observed in the donor
fleas which had been fasted for about 24 hours
were allowed to feed till half-an-hour after the
donor's death. In six out of the seven experiments
the fleas got an infective feed for a period of nearly
five hours, while in the seventh it was two hours.
In one case only (experiment 2, with 1,600 fleas)
was transmission successful. In experiment 5
the receptor died after three days. There was
slight oedema where the infected fleas had fed,
but blood smears taken after death showed no
bipolar organisms. Heart blood and bone marrow
examined bacteriologically also yielded negative
results. The spleen was slightly haemorrhagic,
endocarditis was present and also slight haemorr-
hagic gastritis and enteritis.
INFECTIVITY OF FLEAS AFTER VARYING PERIODS
OF FASTING
Thirty-four lots of infected fleas, each containing
about 10 individuals, were examined bacteriolo-
gically after fasting for 1 hour to 120 hours. Table
II shows the results.
TABLE II
Infectivity of fleas after varying periods of fasting
Period of fasting
(hours)
1
12
16
20
24
36
40
41
43
48
58
60
64
67
72
82
84
88
96
112
120
Total samples
examined
4
2
1
3
4
2
1
1
1
2
1
1
1
1
2
1
1
1
2
1
1
34
Positive results
with
2
1
0
2
3
0
1
0
1
1
0
0
0
1
1
0
0
1
0
1
0
15