S. GANAPATHY IYER AND Z. A.
HASHMI
155
pastcurella organisms in normal rats, while Meyer
and Batchelder [1926] isolated 34 strains of paste-
urella from wild rats during plague eradication
measures along the Pacific Coast. In India, Raj-
gopalan and Gopalkrishnan [1939] recorded an
outbreak of pasteurellosis in white mice. There
is, however, no proof that these Pasteurella
strains were pathogenic to cattle. In absence
of any direct evidence of this type, X. cheopis
could not be accepted as a vector in haemorrhagic
septicaemia. For the present, therefore, it can
only be stated that C. felis appears to be an in-
efficient vector and is normally incapable of trans-
mitting haemarrhagic septicaemia in buffaloes.
SUMMARY
Experiments on transmission of P. septica
from rabbit to rabbit and from rabbit to buffalo
were tried using C. felis, the common dog flea.
The experiments in rabbits were positive and
a very small number of fleas was effective. On
the other hand, in 11 experiments with buffalo-
es and up to 3,000 fleas as transmitting agents
eight failed completely, one was positive and two
were doubtful. Since most of the experiments
with buffaloes were negative in spite of optimum
conditions as regards the number of fleas and
high virulence of the organism, it seems unlikely
that in practice Pasteurella in bovines is trans-
mitted by the class of insect. Pasteurella
was found in the faeces of fleas fed on infected
rabbits and then fasted for 48 hours. The orga-
nism was also found in the bodies of infected
fleas which have been fasted for at least 72 hours.
ACKNOWLEDGEMENTS
My thanks are due to Mr Zafar Ali, L.V.P.,
of this Institute for making bacteriological ex-
amination of fleas, and Dr F. C. Minett for
guidance and assistance in compiling this paper.
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STUDIES ON NEWCASTLE (RANIKHET) DISEASE VIRUS
STRAIN DIFFERENCES IN AMENABILITY TO ATTENUATION
By S. GANAPATHY IYER and Z. A. HASHMI, Poultry Research Section, Imperial Veterinary Research
Institute, Izatnagar
(Received for publication on 11 January 1945)
IYER and Dobson [1940] attenuated an English
strain of Ranikhet disease virus. This paper
is based on further work on three strains of Rani-
khet disease virus carried out at this Institute.
MATERIAL AND METHODS
Three virulent strains of Ranikhet disease virus,
designated as Lines i, ii and iii, received from
widely separated localities in this country, were
selected for study. The technique of Iyer and
Dobson [1940] was used throughout. Six to
twelve-months old cockerels bred on the Institute
farm were used for the virulence tests. Fertile
eggs for virus passage were also secured from the
same farm.
RESULTS
Line i. This strain remained fully virulent after
69 successive passages, carried out over eleven
months.
Line ii. No change in pathogenicity was obtained
by 32 serial passages carried out over five months.
Line iii. Table I gives the results obtained
with passages carried out over 12 months.
H