The results in this series of cases indicate that Sia's globulin precipitation test is positive in certain cases of leprosy, particularly in the nodular and mixed types of the disease. Of the 32 cases of leprosy on which this test was made 17 of them were positive. The intensity of the reactions varied from 1 to 3 plus. In all of these cases the percentage of blood serum globulin was estimated. The nodular cases showed an average of 4.68 per cent; the mixed cases, 4.52 per cent; the active maculo-anesthetic cases, 4.23 per cent and the latent maculo-anesthetic cases an average of 3.11 per cent.
The value of the test from a diagnostic point of view in the differentiation of kala-azar and schistosomiasis from leprosy is not of importance. Although the three diseases are often found endemic in the same regions, the clinical differences between the former diseases and leprosy are sufficiently distinct to prevent any confusion in their differential diagnosis.
It is impossible to see any relationship between the serum globulin content of the blood of the cases treated with the ethyl esters of chaulmoogra oil, and those not treated, sufficient to make it of any value as a clinical test for determining the efficacy of such treatment. It is suggested, however, that the blood serum globulin and the precipitation test be studied in this relation to ascertain whether or not there is any decrease in the amount of serum globulin or the positiveness of the test parallel with clinical improvement.
Apparently the serum globulin in long standing cases, in which the infection has become clinically latent, does decrease to a point within its normal range. This has been true of the maculoanesthetic cases in this series which have never had any form of treatment, and suggests the close relationship of activity of infection and serum globulin content in leprosy.
It is interesting to note the differences in the protein partition of normal blood and that of kala-azar, schistosomiasis and leprosy. The total protein content of the blood from leprosy cases is higher than in the first two diseases. In kala-azar and schistosomiasis the serum globulin increases at the expense of the serum albumin which decreases to a point 50 per cent below that of normal blood. In leprosy the serum albumin remains practically normal. Although the serum globulin of leprosy does not reach the height it does in kala-azar and schistosomiasis, the total protein content exceeds that of these two diseases because of the behavior of the serum albumin.