Without the last, a differential diagnosis between quinin poisoning and blackwater fever is often impossible. This is especially true when quinin was administered before the paroxysm and when the disease is of intermittent type. Blackwater fever is likewise differentiated from paroxysmal hemoglobinuria only by the presence of parasites. Not much can be judged from the effect of cold, since, according to Corre, cold frequently plays an active role in malarial hemoglobinuria. When the fever is continued and remittent, quinin poisoning and paroxysmal hemoglobinuria need scarcely be considered.
In regions where malaria and yellow fever are simultaneously endemic, blackwater fever has been frequently, especially in earlier times, confused with yellow fever, yet the two conditions are easily differentiated if we remember that hemoglobinuria never occurs in yellow fever, and only seldom hematuria, while other hemorrhages, especially hematemesis (vomito nero), common in yellow fever, are rare in malaria . Moreover, yellow fever attacks people who never suffered from malaria; it begins without prodromes; the fever is continued; the icterus slight, and is visible first on the third or fourth day; there are two periods of the disease to be recognized, etc. Finally, in addition to all these clinical symptoms, there is the blood examination, with its positive conclusions.
Confusion of blackwater fever with acute yellow atrophy of the liver, phosphorus poisoning, and Weil's disease is easily avoided.
The prognosis is serious. When the initial symptoms are not too severe; when the patient is healthy and his resisting power has not been injured by alcohol, syphilis, or other disease, the prognosis is more favorable. In the course of the disease an intermittence of the paroxysms is to be hoped for, since a continuance of the fever and the other symptoms aggravates matters.
Persistent vomiting, lasting several days, is dangerous, on account of the impossibility of nourishing the patient. If profuse diarrhea is present at the same time, the rapid enfeeblement is all the more to be feared. Sudden sinking of tension with increased frequency of the pulse and singultus are to be regarded as inauspicious symptoms. Algor and coma are likewise ominous. Anuria for several days is very serious, yet not necessarily fatal, since secretion not rarely begins again. Polyuria is usually a favorable sign, yet there are cases (Berenger-Feraud, Corre) in which a fatal termination occurred in spite of a marked polyuria-possibly even as the result of it.
The intensity of the icterus, as well as the more or less dark color of the urine, is of no prognostic significance, though it is important to watch for symptoms of acute nephritis, since this makes the prognosis worse.
We have already stated that in severe cases of blackwater fever other pernicious symptoms, like algor, collapse, coma, and convulsions, sometimes occur, and usually with a fatal result. These conditions are not to be regarded as true complications, but as further expressions of the malarial infection. When anuria occurs, the suspicion of an acute uremia naturally arises, and in this case we may speak of a complication. The observation of the clinical symptoms in vivo under these circumstances, is of less aid to a proper conclusion than the postmortem finding. During the course of the disease the only symptom indicating the condition would be the occurrence of urea in the vomit. Guillaud has described three cases of blackwater fever with severe uremic and nephritic symptoms. The autopsy showed in each case an acute nephritis.
Among the hemorrhages, petechias, retinal hemorrhages, and epis taxis are the most frequent. Less common are melena, hematemesis, and hemorrhages into the pleura and the pericardium. According to Steudel, pleuritis sicca is a frequent occurrence.
Among the sequelae, severe anemia and cachexia must be mentioned. The stomach frequently continues very sensitive, and as a result of the persistent bilious vomiting there may be loss of appetite and nausea. Intestinal action is likewise frequently altered. Colique seche is occasionally seen.
In the great majority of cases the kidneys endure without injury the irritation produced by the hemoglobinuria, though acute nephritis sometimes develops as a consequence. This may manifest itself immediately after the attack by the occurrence of numerous epithelial, granular, and corpuscular casts in the scanty albuminous urine (cases of Guillaud, Kelsch and Kiener), or it may develop and become evident only after the disease has passed. In these cases the question must always be considered whether the individual had not nephritis previously.
Convalescence is usually protracted on account of the severe anemia and the gastro intestinal disturbances. Chronic malarial cachexia lasting throughout life is not infrequent. After mild attacks the general health may be at once restored.
For the pathogenesis of blackwater fever we refer to the proper section. Here we will only say that the essential factor consists in a sudden enormous destruction of red blood corpuscles and their simultaneous solution. That the number of destroyed erythrocytes must be uncommonly large to permit the blood coloring matter as such to pass the kidneys is evident from Ponfick's experiments and from the blood examinations.
According to Ponfick's experiments, about one sixth of the entire number of red blood corpuscles must be destroyed in order to produce hemoglobinuria. If a smaller number succumb, the liver activity is sufficiently great to use them up in the elaboration of bile.
The final cause of the destruction of the blood corpuscles is unknown. We mentioned- previously that the parasites found in black water fever are in no way distinguishable morphologically from the parasites of the ordinary estivo autumnal fevers. Whether they are more virulent or have the power to excrete a specific hemolytic poison are conjectures that cannot at present be substantiated.
Blackwater fever is evidently not more severe on account of a greater number of parasites or higher temperatures, because it does not manifest these.