Banti's disease and tropical splenomegaly clinically approach very closely, and can only be excluded by a microscopical examination of the liver and spleen juices, or of the blood. Similarly, malignant disease of the abdomen, so often associated with irregular chronic fever, in the absence of a satisfactory microscopical examination of liver or spleen juice, may be difficult to distinguish from kala-azar.
On the discovery of the germ cause of kala-azar, and the fact that this disease is widely distributed throughout the tropics and sub-tropics, there was at first a tendency to regard all cases of febrile tropical splenomegaly which are not associated with malaria, trypanosomiasis, and other well-known conditions, as kala-azar. Further observation and experience have considerably modified this view, since it has been found that a proportion of such cases do not show the Leishman body either during life or after death. Possibly other protozoal germs, as yet unrecognized, are responsible for some of these cases. So that, in any given case of tropical splenomegaly, until the Leishman body is found it would be rash to pronounce a positive diagnosis of kala-azar.
The discovery of the Leishman body in the blood,*[1] lymph, or tissues, therefore, is the only reliable indication of kala-azar. In the first instance it should be sought for in the blood, or in material obtained by puncture of lymphatic glands, after appropriate staining. A high-power immersion lens is indispensable, and every leucocyte or scrap of tissue must be carefully scrutinized for the little oval body with the round or oval nucleus and rod-shaped blepharoplast. Several films, especially at the edges of the preparations, must be searched in this way before recourse is had to splenic or, better as being less dangerous, hepatic puncture.
Splenic puncture must not be lightly undertaken. A preliminary examination of the blood should always be made, not only with a view to ascertain
- ↑ * Patton found the parasite in the blood in the first blood-film examined in 42 out of 84 cases, and in the remaining 42 after more or less prolonged examination of from two to twenty slides.
