PREDISPOSING CAUSES 



I22I 



Sambon, in 1898, having in mind the haemoglobinuric fevers of animals, 

 brought forward the theory that human blackwater fever would probably be 

 found to be a piroplasmosis, and has informed us that on one occasion Sir Patrick 

 Manson and he saw one body in a red blood-corpuscle of a case of blackwater 

 fever which very closely resembled the bacillary form of Theileria, but it 

 is possible that this was merely a peculiar form of Laverania malavice. 



The parasites which have been described are becoming numerous. There is 

 a bacillus by Yersin in the renal epithelium, which has since been shown to be 

 a strain of Bacillus coli communis ; while the other parasites suggested as 

 possible aetiological factors are a blood parasite by F. Plehn, which he now 

 identifies with the subtertian malarial parasite; and a double-contoured 

 parasite in the red corpuscles by Fisch, which has not been confirmed. A 

 body resembling a Piroplasma has been described by Forau, but has been 

 criticized by Stephens, as resembling the fragmentation and flagellation of 

 erythrocytes commonly seen in malarial anaemia in the tropics. Leishman 

 has described cell inclusions varying from i to 5 ;u in diameter, and usually 

 found in large mononuclear cells of endothelial origin. These inclusions 

 are either structureless, homogeneous, circular forms, or ring forms. They 

 are embedded in the cytoplasm of the cell, and usually assume a chro- 

 matin colour with Romanowsky's stain. As a rule, several inclusions are 

 found together in the same cell; more rarely they are solitary. Leishman 

 considers that possibly they are Chlamydozoa. These bodies have baen 

 adversely criticized by several observers, especially by von Schilling-Tor gau, 

 who considers them to be plasmosomata, and Low has found similar bodies 

 in other diseases. Balfour has seen these inclusions in a case of blackwater 

 fever and in a case of malaria. Schiifner has tentatively suggested that a 

 form of the disease may be of spirochaetic origin. 



5. Bite of an unknown Arthropod. — Balfour suggests that the disease is not 

 of parasitic origin, but due to the injection of some powerful haemolysin intro- 

 duced by the bite of some unknown insect or arachnid. 



In our opinion blackwater fever is a disease of its own, though 

 we freely admit the existence of haemoglobinuria from quinine as 

 well as from other drugs, such as chlorate of potash, of which we 

 know of a case at first diagnosed as blackwater fever. 



Predisposing Causes. — The predisposing causes of blackwater fever 

 appear to be first racial, second bodily. With regard to the first, 

 the immigrant European suffers more than the native, though 

 the disease also attacks natives and half-castes. This racial dis- 

 tinction is, therefore, probably due to some acquired or inherited 

 immunity. It is said that a person is usually not attacked until 

 after residence for at least a year in the endemic area. 



The second series of predisposing causes appears to be anything 

 which lowers the vitality of the body — cold, change of climate, 

 another disease — e.g., malaria, syphilis — or certain drugs. 



Pathology. — As the aetiology of the disease is uncertain, the 

 pathogenesis is also little understood. 



Christophers and Bentley have brought forward an explanation of the patho- 

 logy. Their views may be summarized as follows: — -Laverania malaricB, the 

 subtertian parasite, acts upon the endothelial cells of the blood capillaries of 

 various organs, but especially upon those of the spleen and liver, stimulating 

 them to excessive destruction (erythrokatalysis) of red blood cells by phago- 

 cytosis. This phagocytosis results in the production of an auto-haemolysin 

 of the nature of a haemolytic amboceptor, which is retained in the endothelial 

 cells until set free by some exciting cause, which may be a chill, overexertion, 

 etc. The result of this excitation is to suddenly set free in quantity this 

 haemolysin, which destroys the red cells by solution in the plasma (lysaemia). 



