S.
GANAPATHY
IYER
7
liver, spleen and kidneys may be congested. The trachea is usually unaffected
but may show slight congestion and contain mucus. The lungs show little
organic change, which is strange in view of symptoms of respiratory distress
shown by the birds during life. In chronic cases where the fowls show nervous
symptoms the nerves seldom show macroscopic changes, but, microscopically,
areas of cellular infiltration may be seen. The brain is congested and the
meningeal vessels are injected. The exact nature of the change depends upon
the extent of neurotropism.
Kylasamier [1931] described the pathological histology of the gastro-
intestinal lesions. The lesions in the proventriculus are described as a distor-
tion of the gastric follicles and, in the intestines, the villi are distorted with
superimposed bran-like deposits.
Burnet and Ferry [1934] made a comparative study of the viruses of fowl
plague and Newcastle disease, using the technique of inoculation of the chorio-
allantoic membrane. According to Burnet and Ferry, sections of the infected
membrane showed the principal lesion to be a patchy ectodermal proliferation,
followed by, or associated with, gross vacuolation of the epithelial cells and
eventual necrosis (Plate IV, figs. 4, 5 & 6). In some areas, the vacuoles con-
tained acidophilic bodies. In fowl plague, the membrane shows an almost
complete absence of ectodermal cells, although both the viruses cause the death
of the growing embryo in 24 to 48 hours. Burnet and Ferry state that when an
egg containing an embryo, which has just died after inoculation, is opened and
examined, there are apparently certain lesions characteristic of the disease.
The chorio-allantoic membrane is moist, with oedema and cloudiness arising
from cellular infiltration. There are also irregular whitish opaque areas
representing the areas of ectodermal proliferation (Plate IV, figs. 2 & 3). Small
petechial haemorrhages are fairly numerous and sharply outlined, particularly
on the neck and along the sides of the ventral aspect of the body (Plate IV,
fig. 1). The author confirmed all these findings in a large number of serial
passages of the virus through eggs. Minute pin-point haemorrhages were
usually seen on the wings, claws and the under surface of the abdomen. In
some of the eggs, the legs were dark-red in colour.
Control
Hygienic measures, that is the adoption of the general principles of segre-
gation and disinfection are the only possible methods of control known at the
present moment [Sahai, 1937], but, under field conditions, hygienic measures
are of limited value, especially in India where the question of extermination of
the infection by the destruction of all the sick and in-contact fowls is hardly
possible. Haddow [1937] suggested splitting the flocks into small batches and
distributing these as far as possible from each other. The disease is notifiable
in Great Britain. The order of 1936 which came into operation there on 11
January 1937 suggests preventive measures which consist of timely diagnosis,
the isolation of incontact birds, the prevention of movement of birds from the
infected area, the quarantine of freshly purchased birds for two weeks, the
disinfection of infected crates, utensils, houses, nest boxes, runs, etc., the
avoidance of spread by attendants and the hygienic disposal of excreta and
dead birds.