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led Türk, whose work was theu unknown to us, to point out the diagnostic value of this increase in the diagnosis of malaria. We have, then, two auxiliary methods in the diag- nosis of malaria :-
1. The detection of pigmented leucocytes.
2. The increase in the percentage of the large mononuclear leucocytes.
Applying these subsidiary tests to blackwater fever in which parasites are, as a rule, absent, we were able to show that nearly all of these cases, apparently nou-malarial, are, in fact, malarial, presenting pigmented leucocytes and an increase in the large mononuclear leucocytes. In our first series of 16 cases, although only in 3 were parasites found (about 19 per cent.), yet using these subsidiary tests no less than 93.7 per cent, were shown to be inalarial.
We thus, as the result of our work, established on a microscopical basis, the proof of what had been previously mainly conjecture.
Blackwater fever, then, is malarial in origin. It cannot, however, be considered as simply a severe form of malarial fever, for there is yet another side to the question.
In 1860 Tomaselli first published a series of cases in which symptoms of blackwater fever followed upon the administration of quinine, not necessarily in large doses, but almost invariably in those who had suffered much from malaria.
A. Plehn and F. Plehn, in the Cameroons, have published most accurate histories of very many cases of black water, and with very rare exceptions they always followed upon the administration of quinine.
Koch has so strongly advocated the quinine factor in black water that it appeared at first as if he denied its malarial origin, but this is not so, as is quite clear from his later writings. He holds that quinine is the immediate exciting cause, but that a predisposition, determined by many attacks of malarin, is necessary.
Many of those who hesitated to give their assent to these views now acknowledge that there is such a thing as quinine baemoglobinuria occurring in malaria cases. This acknowledgment amounts to a recognition of the quinine origin of blackwater fever, for the two conditions are absolutely indistinguishable. We have ourselves seen cases which were to us clearly of this nature and our views are summed up by saying that blackwater fever is a disease malarial in origin, and dependent on blood changes occurring after many malarial attacks, and generally, if not always, in relation to an actual attack, but that also it is undoubtedly almost invariably induced by the taking of quinine in this state.
It has been argued that if quinine is the cause of blackwater fever it is a dangerous drug, and should not be used in malaria, but this argument is not a good one.
It is as we believe in the malarial chronic that blackwater almost always occurs. We believe that in such a person quinine is dangerous. If, however, quinine is efficiently used as a preventive of malaria no fear need be held of it. It is inadequate quinine treatment, because malaria is thereby not really combated, which is the danger.
While then we consider that the malarial origin of blackwater fever has been established by us on a basis of microscopical evidence, yet we may briefly consider some other aspects of the question, as it will enable us also to answer some of the objections of a purely general character, which have hitherto been raised against its malarial origin.
1. It has been urged that the distribution of blackwater fever and malaria is not the same. Even if this statement were true it must not be forgotten that the distribution of mild malaria and severe malaria is by no means the same. Thus, the mortality from malaria in the few still remaining foci in Northern Europe is in no way comparable to that of the Roman Campagua, nor, again, is the severity of malaria in Northern Italy comparable with that in the South. We cannot, indeed, speak of the distribution of malaria as a whole. If, however, we confine our remarks to regions of intense malaria we believe that the distribution of blackwater fever will be found to tally exceedingly closely with that of malaria. The distribution of blackwater fever is, we believe, consider- ably wider than is generally supposed. Thus in the Bengal Duars, in ludia, blackwater was found by us to be as common as in Africa, a fact to which the literature of the distribution of blackwater fever gave us no clue.