4
REPORT OF THE KING INSTITUTE, GUINDY
Saidapet Range have been given. Most of these are done with cups already
tested and in general use and so older. The general rates in Saidapet this year
were 99.3 per cent. case success and 96.5 per cent. insertion success as against
99.3 and 97.3 last year.
Further evidence on the potency of lymph as issued is given by an analysis
of returns received from 87 individual cups of lymph issued for which full returns
were available. Lymph from these cups was sent out on 14,000 different
occasions to various vaccinators. 7,500 returns which include returns for each
of the 87 cups gave a case success rate of 100 per cent. Therefore, the lack of
complete success of the others cannot have been due to variation in the lymph as
issued because elsewhere such cups gave 100 per cent. success rates.
(c) The immunising value of lymph. —It is important that lymph should not
only be potent as regards the numerical strength of the specific virus, but that it
should also be capable of giving adequate protection against smallpox after a
successful vaccination. This may be called the immunising value of lymph. At
present this cannot be measured directly from the statistical data available on
account of the concurrent variation in the extent of vaccination, the efficiency
of vaccinators, etc. But although this is so, yet it can confidently be asserted,.
that the figures recently given by the Director of Public Health, Madras, in his
report for 1926 (paragraph 60, page 19) showing that the death rate from small
-pox has steadily diminished in the last 5 years from 1.8 per mile to 0.4 per mile,
could never have been obtained without a high real potency of the lymph used,
however much the other factors mentioned had also contributed, as is very
likely, towards the gratifying result. In this laboratory in the last two years we
have estimated the immunising value of lymph against vaccinia itself and have
found that the lymph manufactured has gained considerably in its immunising
value. Rabbits were used as test animals and the amount of protection afforded
by the first (or primary vaccination) was determined by a revaccination at
a later date. In the beginning it was found that the minimum period of protection
thus afforded was very small—about 40 days on the average. With some of the
latest batches of lymph the average protection afforded is now nearly three
months, so the lymph has definitely gained in immunising value. Experiments
on monkeys to test the immunising value against actual smallpox virus are
projected.
4. The purity of lymph.—For the purpose of purification reliance is placed on
the action of glycerine during cold store and during transit—particularly the
latter, where on account of higher temperatures, the germicidal action of
glycerine is very rapid. The action of chloroform was again investigated this year.
The results along with those for ether and alcohol which were also tried were not
satisfactory. So, for the present, we conclude that on account of the very high
temperatures prevailing in the Presidency it would not be advisable to adopt
any other method of purification of lymph in addition to glycerination.
It must always be remembered that the majority of the extraneous organisms
that are found in vaccine lymph are non-pathogenic. The actual micro-organic
content of the lymph is not of any importance so long as all the pathogens are
excluded. With this object in view additional precautions are now taken before
the lymph is finally issued for general use in the Presidency. Each cup is tested
bacteriologically both ærobically and anærobically. Organisms which are grown
anærobically are further tested for pathogenicity by the Guinea pig inoculation
test. These are kept under observation for over a week, and if the animals
remain in perfect health at the end of that period, the cup is passed for general
use. Adequate precautions are taken at various stages of manufacture of lymph
to guard against extraneous contaminations, and it is interesting to note that out
of 178 cups that were manufactured and tested in the way described above, all
except one gave negative results in Guinea pigs. From this single cup a gram
negative bacillus of the Gærtner group was isolated. This cup was again tested
two months later and it was found that the organism was not present. Two
months in cold storage had been enough to purify this lymph. It can be claimed,
therefore, that vaccine lymph as issued to the Presidency does not contain any
harmful extraneous micro-organisms.