8
REPORT OF THE KING INSTITUTE, GUINDY
PART II.—RESEARCHES AND MATTERS OF INTEREST.
(1) Rat flea survey of the Madras Presidency.— This survey which had been
financed by the Indian Research Fund Association was completed the previous
year and its findings published as a set of separate local surveys. In order to
get a better idea of the results Dr. C. G. Pandit and I wrote a complete summary
of our findings which was published in the Indian Journal of Medical Research
for October 1931. In addition a short preliminary paper on this subject by
Dr. Pandit and myself was read by me at the Bangkok Conference of the
F.E.A.T.M. We show that X. cheopis appears to be the most efficient vector of
plague in nature in this Presidency and that the more common species, X. astia,
though it can carry plague, does so very poorly and does not appear to carry
plague infection over from one season to another, for when X. astia alone was,
present epizootics have not carried over in the off season.
(2) Seasonal rat flea survey.—In order to complete the survey just.
mentioned, Mr. P. V. Sitarama Ayyar has been doing a seasonal survey of rat
fleas at Saidapet, Coimbatore and Bellary which typify three different climates.
His paper will shortly be published.
(3) A successful modification of Nijland's cycle in vaccine lymph production.—
In our annual report for the year ending March 1930 it was reported that the
usual Nijland's cycle for seed lymph—ox-calf—rabbit—buffalo-calf—ox-calf, had
been changed by the addition of another buffalo-calf in the series. My idea was
that this extra animal between the rabbit and the final ox-calf would considerably
add to the dilution of the material taken from the rabbit, and in this way lessen
the danger of contamination of the final lymph by an extraneous virus derived
from the rabbit. For it had been suggested that post-vaccinial encephalitis was
due to such an extraneous virus. It is interesting to note that this suggestion
was made among others by Col. W. G. King, C.I.E., I.M.S. (Retd.), the
founder of this Institute. Though, for various reasons this origin of post
vaccinial encephalitis is now thought to be very unlikely, we have adhered to
the modification which I made in the cycle, for we soon found that this step was
increasing the potency of the lymph. This is the first complete year reported on
since this modified cycle was introduced, and its effect is seen in the record
human success rates and yield per calf reported in Part I. When it is borne in
mind that the lymph issued for routine vaccinations was in a dilution of 1 in 7
from January 1930 as compared with a dilution of 1 in 5 in previous years, then
the higher success rates now obtained are still more striking. Drs. C. G. Pandit,
K. P. Menon and Khan Sahib Muhammad Omar Sahib, who have been mainly
responsible for the carrying out of this work, report that, when the second buffalo
is vaccinated with the first buffalo passage lymph, the resulting reaction is not
always satisfactory, many animals show either an indifferent reaction or a total
failure, but when a moderate or a good take is obtained the resulting lymph used
as seed yields a good vesiculation on calves. I suggest that the extra passage
through a buffalo-calf (buffalo-calves here in Madras are less susceptible than ox
-calves) tends to kill out the weaker strains without seriously damaging the better
ones. Thus this modification of Nijland's cycle designed for one purpose has
proved very useful indeed for quite another, and has increased both the yield and
the potency of our lymph.
(4) A study of several strains of streptococci isolated from vaccine lymph by
Drs. C. G. Pandit and K. P. Menon.—During the routine bacteriological ex
- a m i n a t i o n o f l y m p h a n u m b e r o f s t r a i n s o f s t r e p t o c o c c i w e r e i s o l a t e d a n d w e r e
studied in detail as regards their cultural and bio-chemical characters. They
were all found to be of the streptococcus faecalis type. Thus most of them
fermented marmite and salicin and lactose, and some raffinose. As was first
noted by Dible, they could be cultivated in media with a very wide range of
p.H. They were very resistant to heat—a character usually associated with
enterococi. They were also resistant to 50% glycerine.