166
Susceptibility of Ducks to Newcastle
in the coop, and, on the 19th day, the infection
was implemented by injecting them each with
10 c.c. virus. As they showed no reaction they
were bled and killed 33 days after the first injection.
(3) Two more ducks were injected with 10 c.c.
virus on 21 November 1939. One of these
died as a result of helminthic infection on the
14th day, while the other showed no reaction
and was reinjected with 10 c.c. virus on the 15th
day. It remained well and was bled and killed
on the 29th day after the first inoculation.
(4) Two eight weeks-old ducklings were injected
each with 1 c.c. virus. They showed no reaction;
on the fifth day one was killed and an emulsion
of its liver and spleen was subinoculated into a
fowl to test the infectivity of the tissues. The
fowl remained healthy and was later shown to
be susceptible to Newcastle virus infection.
The tissues from the duckling, therefore, contained
no virus capable of infecting the fowls.
The second duckling also showed no reaction
to the inoculation and was killed on the 20th
day. The autopsy of this bird revealed nothing
unusual.
TABLE I
Inoculation of Newcastle disease virus into ducks
and ducklings
Experi-
ment
1
2
3
4
Birds and
number
Duck
507
and 443
Duck 633
and 764
Duck
633
and 384
Duckling 1
and 2
Date of
inoculation
10-11-39
6-12-39
17-11-39
6-12-39
21-11-39
6-12-39
21-6-40
Dose of
fowl virus
suspension
1.0 c.c.
10.0 c.c.
Coop contact
infection
10.0
c.c.
subcut
10.0 c.c.
10.0 c.c. into
duck 384
1.0 c.c.
Result
No reaction
No reaction, bled
and killed 20-12-
39
No reaction
No reaction, bled
and killed 20-12-
39
Duck 633 died from
other causes; no
reaction in duck
384
No reaction, bled
and lulled 20-12-
39
No reaction. Duck-
ling 1 killed 5th
day, inoculated
organ suspension
into a fowl and
into fertile 11
day
incubated
hen eggs with
negative results;
duckling
2
killed 20th day,
nothing unusual.
Experiment II (Table II)
Serum-virus neutralization. Serum samples, col-
lected from ducks that had been treated with
the virus were pooled and examined for the
presence of neutralizing antibodies by the in
vitro method. Tubes were put up containing
serum and virus and, after two hours contact at
room temperature (18ºC.), or after 18 hours
contact at 37ºC., were inoculated into susceptible
fowls and fertile 11 day-incubated hen eggs
(only fowl inoculation has been shown in Table
II). Suitable control tubes were also prepared
using the serum of ducks that had not been
inoculated with the virus. In no case was the
virus neutralized, since the test fowls and chick
embryos died of the infection.
TABLE II
Serum virus neutralization tests
Contact of
serum-virus
mixture for
2 hours room
temperature
Do
Do
18 hours 37ºC
Do
Date
1-1-40
Do
Do
16-1-40
Do
Fowl
No.
2080
2082
2078
2109
2108
Inoculation details
(1.0 c.c. subcuta-
neous)
Pooled duck serum
obtained after
virus inoculation
+ virus, equal
parts
Do
but with serum
diluted 1 in 10
Normal
duck
serum + virus,
equal parts
Pooled
duck
serum obtained
after
virus
inoculation
+
virus,
equal
parts
Normal
duck
serum + virus,
equal parts
Result
Died of New
castle discase
8th day
Do
7th day
Do
5th day
Do
8th day
Do
6th day
CONCLUSIONS
The Pennine ducks and ducklings used i n
this work failed to react to small or big doses
of virus or to contact infection. The serum
from ducks inoculated with virus revealed no
antibodies.
In confirmation of Dobson's [1939] findings,
the ducks and ducklings used in this work were
resistant to Newcastle disease virus.
SUMMARY
The ducks and ducklings used in this work were
found to be resistant to Newcastle desease virus.
REFERENCES
Cooper, H. (1931). Indian J. vet. Sci. 1, 107
Dobson, N. (1939). Proc. 7th World's Poult. Congr. 250
Doyle, T. M. (1927). J. comp. Path. 40, 144
Farinas, E. C. (1930). Philipp. J. Agric. 1, 311
Picard, W. K. (1934). Ztb. Bakt. I. 132, 440