Serum from East African patients with T. rhodesiense infection, lesihmaniasis, and normal human donors was analyzed for γ globulin and IgM levels.
The total γ globulin level was found to be higher among healthy African than among healthy American donors. IgM levels were markedly elevated (up to 10 times the normal) in 42 of 45 cases of T. rhodesiense infection and at all stages of the disease, even when total γ globulin levels were low. In contrast, in all of the seven leishmaniasis cases (except one early infection) IgM levels were normal in the presence of extremely high total globulin levels.
During a period of 1 to 2 months of treatment, the IgM levels dropped only slightly or not at all in T. rhodesiense infection. Further studies should be made to determine the correlation between this finding and the relapse rate.