288
M. K. SREENIVASAN AND S. W. H. RIZVI
bringing infected nodules into direct contact with
healthy skin, as well as by all other possible methods,
failed. We have succeeded, however, in transmit-
ting the goat Demodex to four out of six healthy goats
in the following ways.
Group 1. Three young goats (two females and
one male) and one hill-bull were used. Fresh infec-
tive material, obtained from a goat, was applied
on both sides of the neck up to the bases of the
ears after closely clipping the hair. A second
application was similarly made a week later.
Group 2. Three young goats (two females and
one male) and one hill-bull received the same material
as Group 1, but the skin was shaved before applying
the infective material. A second application was
made a week later.
Hill-bulls were included in these experiments to
see whether the mites of one species affected another,
as supposed by Zurn, Babes, Lewandowsky and
Scott [quoted by Hirst, 1921].
All the experimental animals were kept under
strict isolation to avoid any chance infection. A
month later none was showing signs of the disease.
Later examinations were made at weekly intervals
and at the end of four months one goat in Group 1
showed a few millet—sized nodules at the bases and
pinnae of the ears and on one shoulder ; Demodex
was found on microscopical examination of the
contents. One. goat in Group 2 showed similar
lesions at the end of five months and one more in
each of Groups 1 and 2 developed the disease at
the end of eight months. The two male goats, one
in each group, and three kids born approximately
five months after the experimental infection of the
mothers, did not show infection. It is interesting
to note that in none of the four goats experimentally
infected with the disease, did lesions develop at the
seat of application of the infective material. This
may probably be due to the close clipping and
shaving which made the part unsuitable for the
mites to establish themselves and forced them to
migrate to the neighbouring parts covered with
hair.
Out of the two bulls used, one in Group 1 showed
a few millet-sized nodules on shoulders and dewlap
after four months. The material collected from
this bull showed demodectic mites. It was at first
thought that this was experimentally transmitted
infection, but on careful microscopical examination
the mites proved to be cattle Demodex, being morpho-
logically identical with specimens collected from
a calf at Hissar in 1936 by Mr M. Abdussalam who
kindly lent us his collection for comparison. From
this it may be concluded that this bull was incubating
a natural infection of Demodex at the time of coming
under experiment. But for this detailed study of
the mites and their comparison with identified
specimens, we might have erroneously believed like
some other workers that Demodex of one host species
can affect another.
In the case of the artificial infection in goats the
lesions were small and of non-progressive type unlike
the natural infection. In one animal they disappear-
ed in about nine months. These goats were in good
condition and are again in kid. The non-progressive
nature of the disease may be due to the goats being
in prime condition.
DISCUSSION
In its principal characters the mite (Plate XVIII,
fig. 4) agrees with the description given by Railliet
[1895] and Cram [1925] and the lesions also agree
in the main details with goat demodecosis reported
in foreign countries.
The source of the original infection could not be
traced but it is presumed that one or two of the
goats were infected before purchase and that they
passed the infection on to others by long cohabita-
tion. Judging from the experimental data given
above the period of incubation in natural cases
appears to be not less than four months.
Mere occasional contact does not introduce the
disease, as two Barbari bucks which came in close
but occasional contact for one year with the infected
goats have shown no sign of infection. Further
a batch of experimental goats was already housed
in the same kraal since September 1933, and came in
occasional contact with the infected flock without
getting infected. The non-infectivity of the kraal
is shown by the fact that the experimental goats
referred to above are still healthy. Both pregnant
and non-pregnant goats were found affected ; this is in
contradicton to the belief of Rissling and Martin
[quoted by Cram, 1925], who thought that only
pregnant goats suffered.
SUMMARY
1. Demodectic mange of goats is recorded for the
first time in India.
2. The mode of spread of the infection appears
to be through long cohabitation.
3. Sucklingkids in contact with diseased mothers
have not been affected.
4. The infection has shown no special affinity for
pregnant and long-haired goats as reported in foreign
countries.
5. Experimental transmission was shown to be
possible, infection occurring after an incubation
period of 4-8 months.
REFERENCES
Cram, E. B. (1925). J. Amer. vet. med. Ass. 66, 475-80
Durant, J. (1944). Vet. Med. 39,268-70
Hardenbergh, J. G. and Schlotthauer, C. F. (1925). J.
Amer. vet. med. Ass. 67, 486-89
Hirst, S. (1921). Studies, on Acari. The Genus Demoder,
Owen. British Museum of Natural History, London
Mohler, J. R. (1940). Rep. U. S. Bur. Anim Ind., 82