322
From the 28th of March to the 9th of April, the serum from horse No. 3 was
tried; 19 patients were treated, of whom 10 died and 9 recovered.
From the 12th to the 23rd of April, the serum from horse No. 1 was again used
(2nd bleeding) ; 41 patients were treated, of whom only 11 recovered.
From the 29th of April to the 12th of May the serum from horse No. 3 (2nd
bleeding) was tried. Of 24 cases treated, the results were 12 recoveries and 12
deaths.
From the 22nd to the 26th of May the serum of horse No. 1 (3rd bleeding) was
once more used; 6 patients were treated, of whom 1 recovered.
From the 12th of May to the 3rd of June the serum of horse No. 3 (3rd bleeding)
was again employed; 12 patients were treated, of whom 9 recovered.
Simultaneously, "with the serum of horse No. 1, the sera from horses Nos. 2 and 4
were used ; of 22 patients treated, 10 recovered. The serum of horse No. 1 gave,
therefore, in every instance less recoveries than any of the other sera. The occur-
rence of a sequence of inferior results from one serum ( which results were, however,
still better than those obtained by the ordinary treatment) can only be explained by
a variation in the degree of efficacy. The difference in the results, 18 recoveries
in 71 patients treated with the serum of horse No. 1, and 40 recoveries in 77
treated with the serum of the other horses, is so considerable that it cannot be due
to chance.
The recovery rate (vide table, page 3) obtained from the use of the serum
prepared in Florence is considerably reduced by the failure of the first horse with
the serum of which the largest number of patients was treated. For, if from 257
cases treated with the serum obtained from Florence are deducted those injected
with the serum from horse No. 1, the recovery rate is 52.09 % instead of 43.57 %.
The fact that the later bleedings of this horse did not yield better serum
tends to show that the horse was a priori refractory to effective immunisation.
In fact, some horses seem never to give active serum. This is also observed in the
preparation of other sera, as, for example, in the preparation of the anti-diphtheric
serum. A knowledge beforehand as to whether a horse will or will not give an
active plague serum is as yet impossible.
The table given above shows further that the recovery rate from the serum
prepared in Bombay is up to now 9% less than from the serum prepared in
Italy. It is difficult at present to account for this. It may be due to the increased
virulence of the disease in 1899, and to the confidence with which the most desperate
oases were subjected to the treatment by Dr. Choksy, the Medical Superintendent
of the Arthur Road Hospital ; or it may be explained by the fact that the horses
have been bled only twice, as there are strong reasons to believe that the serum
improves with every bleeding. The race of the horses and the climatic conditions
in India might also lessen the resistance of the animals to the immunising injections
und impair their faculty to produce the substance which is the curative agent of
the serum.
Tho observations recorded in this report were made from the 12th of March
to the 31st of October 1898 with the serum prepared in Italy, and from the
1st of February to the 31st of May 1899 with the serum prepared in Bombay.
The total number of patients treated during this time was 475. Serum for 50
patients was, moreover, given to the Indian Plague Commission by order of the
Municipal Commissioner, and some serum was used for the necessary control experi-
ments on animals.
For the preparation of the serum 25 bleedings were made, and 78 immunising
injections performed.