Observations on the patterns of blood IgM levels in the populations of endemic and nonendemic sleeping sickness areas in Kenya.

Increased levels of serum immunoglobulin M (IgM) may be related to a wide range of antigenic stimuli provided by a variety of infections to which people are repeatedly exposed. Most, if not all, of the natural antibodies against bacterial and cellular antigens have been found to belong to the IgM class. It is known that IgM levels in the blood increase in trypanosomiasis but it is not possible to demonstrate trypanosomes in all persons who show raised IgM levels in serological surveys in an endemic sleeping sickness area. Although survey data are limited, this paper discusses the usefulness of IgM tests as an aid to the detection of Trypanosoma rhodesiense infections.