2
Studies on Newcastle (Ranikhet) Disease Virus
heavy losses amongst his poultry flock '. After considerable study Shirlaw
concluded that he was dealing with a virus disease ; in addition, he suggested
the similarity between ' Ranikhet disease ' and ' Newcastle disease ' as reported
by Doyle in 1927. In 1931 Cooper showed that the Indian virus was immuno-
logically indistinguishable from the Java and Philippines and original New-
castle strains. Crows were reported to have died in large numbers [Sahai,
1937, 1 and 2]. Kylasamier [1931] studied a similar widespread virulent
disease of fowls which occurred in the Madras Presidency during 1929-30.
A disease, apparently similar to Newcastle disease, was reported from
Ceylon in 1930 by Crawford. The mortality was usually 100 per cent and, in
addition to affecting chickens, the disease was observed in turkeys, guinea-fowl
and crows. It is not known whether any cross immunity test was carried out
between the Ceylon and the Newcastle strains of the virus.
Konno, Ochi and Haschimoto [1929] and Nakamura, Oyama, Fukusho
and Tomonaga [1933] reported this disease in Korea and in Japan.
In 1931, Newcastle disease was reported from Australia. It was presumed
that the disease, previously unknown in this continent was imported from
overseas. Mortality was 100 per cent of the affected birds. Johnstone
[1933] reported a second outbreak of this disease from Victoria. Although
symptoms differed in some details from those seen previously, it was demons-
trated by cross-immunity tests to be a recurrence of the same disease.
Hudson [1937] from East Africa reported upon a highly fatal disease of
fowls which was transmissible to pigeons. Here again the symptoms were
those of Newcastle disease.
Description of the disease
Newcastle disease is an acute, infectious and contagious disease of fowls,
showing considerable resemblance to fowl plague and is characterized by respi-
ratory distress and a very high percentage of mortality. It is caused by a
filter-passing virus.
Clinically, peracute, acute or chronic forms may be recognized.
(i) In peracute cases the bird usually dies suddenly without showing any
visible signs of illness. In India during the early part of the investigation,
fatal cases with neither symptoms nor lesions were commonly encountered.
In about 90 per cent of the fowls experimentally inoculated at Weybridge by
the author, many, which were normal in appearance in the evening, were
found dead next morning.
(ii) In acute cases, the period of illness lasts for three or four days. The
great majority of cases are of this type. The symptoms described by Doyle
[1927] are in essence as follows :—The affected fowl loses its appetite, crouches
as if trying to hide (Plate I. fig. 1), appears sleepy with eyes either partially or
fully closed (Plate II, fig. 1), and its respiration is rapid. A watery, yellowish-
white diarrhœa with an offensive odour is present. The crop is usually dis-
tended with a sour fluid. A discharge exudes from the nostrils and the mouth
contains a varying quantity of mucus which sometimes hangs in ropes from
the beak. The most characteristic symptom is a long, gasping inhalation
through the half-opened mouth (Plate I, fig. 2). Cyanosis of the comb and
wattles is sometimes observed. Descriptions of the symptoms by several
workers differ only on a few minor points such as the consistent absence of a