Sambon has thought by reason of the clinical resemblance of blackwater to certain haemoglobinuric diseases in cattle, dogs and sheep that such a cause might be operative. These parasites of the red cells are easily discernible in the animal infections but have never been seen in blackwater fever.
The Chlamydozoal Hypothesis.
Leishman has recently noted appearances in the large mononuclear cells of the blood of blackwater patients of certain cell inclusions which he thought to be of chlamydozoal nature and that these chlamydozoa might be etiological factors. Such appearances may not only be absent in marked cases of blackwater but may be seen in conditions other than blackwater fever.
Epidemiology.—There seems to be a consensus of opinion that when malaria is kept in check by proper and persistent quinine prophylaxis or by other antimalarial measures blackwater fever becomes mild in character or even nonexistent. It is those who are careless about quinine prophylaxis or those who expose themselves to depressing influences as cold, wet, excessive fatigue or alcoholic debauches in whom blackwater shows itself.
Overexertion leading to fatigue and chilling seem to be the most common exciting factors. Those in bad health from disease or lack of proper diet seem more susceptible. A peculiar feature of the disease is that it may not be present in a district for a number of years and then assume almost epidemic proportions. Europeans are usually exempt from attacks during their first year in endemic tropical areas. Dudgeon obtained a malarial history in every one of a hundred cases observed by him in the Balkans.
Pathology and Morbid Anatomy
As a result of the excessive destruction of red cells the liver cannot convert the great amount of haemoglobin outpouring into bile pigment so that haemoglobinaemia and haemoglobinuria result. It has been estimated by Ponfick that if ⅙ of the red cells are destroyed the liver is unable to dispose of the liberated haemoglobin and haemoglobinuria results. A damaged liver would be less competent. Various discussions as to autolysins and complement content of serum have arisen.
Dudgeon has demonstrated active haemolysins in the tissues and urine of blackwater fever cases which bodies he was unable to note in other conditions including malaria. There was no evidence of increased fragility of the red cells. There was no evidence of auto-haemolysis. Bile pigment in the plasma occurred in most of the cases which ended fatally.
As a rule we have the pathological findings which go with malaria. As peculiarities of blackwater noted by Whipple and others may be mentioned congestion of the kidneys with purple-colored pyramids. In the spleen the Malpighian bodies are prominent and sharply outlined. Very striking are the necroses of the Malpighian corpuscles of the spleen and focal necroses of the liver. Whipple considers that this speaks for a powerful circulating toxin in blackwater fever which is not present in malaria.