African trypanosomiasis in Canada

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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.

An evaluation of the capillary and latex agglutination and heterophile antibody tests for the detection of Trypanosoma rhodesiense infections

In a small proportion of persons infected with Trypanosoma rhodesiense the parasitaemia is so slight or so intermittent that a positive diagnosis cannot be made by the routine parasitological examination of blood and glandular fluid. By the time the infection is mature enough to be diagnosed by these methods these persons may not readily have access to a diagnostic centre. Some of these infections could be diagnosed earlier by repeated intensive examinations of blood and cerebrospinal fluid, and by animal inoculation tests. A stimulus for investigators to make these examinations could be provided by the results of a simple, rapid, and highly specific immunological screening test that could be made concurrently with the first parasitological examination of suspected cases. The results of two such tests for detecting circulating trypanosomal antibodies are described. One of the tests, the latex agglutination test, is potentially useful as a screening test for persons whose first parasitological examination is negative but whose clinical or social background suggests that they may be infected. This test could find wide application in hospitals and dispensaries, and in the field. Studies indicate that there is little value in testing suspected cases of trypanosomiasis for heterophile antibodies.

Observations on levels of immunoglobulin M in confirmed cases of Trypanosoma rhodesiense infection in the Lambwe Valley

By means of established single-diffusion techniques, immunoglobulin M (IgM) levels in the blood and cerebrospinal fluid of patients with confirmed Trypanosoma rhodesiense infections were studied at the time of parasitological diagnosis, while the patients were being treated with suramin and melarsoprol, and during post-treatment surveillance. During the 3-year study period the number of diagnosed cases in which there was a raised level of IgM in the blood varied considerably, depending on whether diagnosis was made early or late in the course of the infection. In some cases the blood IgM levels returned to normal during preliminary courses of treatment with suramin and in others by the end of a 1-month course of treatment with melarsoprol, while in some other cases they did not return to normal for about 2 years. Similar results were obtained for IgM in cerebrospinal fluid, except that if IgM could be detected at the start of treatment with melarsoprol it was still detectable at the end of treatment. However, cerebrospinal IgM usually disappeared after 2 years. The results indicate that IgM levels are a useful indicator in the diagnosis of the more chronic cases.

The epidemiology of human sleeping sickness in the Lambwe Valley, South Nyanza, Kenya

Human infection with Trypanosoma rhodesiense in the Lambwe Valley area of South Nyanza, Kenya, was first reported in 1959 although T. gambiense sleeping sickness had been the present there since the turn of the century. The two forms of the disease are associated with the presence of the tsetse Glossina fuscipes, which is plentiful and widespread throughout the hinterland, including part of the study area, and G. fuscipes in the thickets near the shores of Lake Victoria and along some of the river systems. Fairly successful attempts have been made to eliminate tsetse by control operations around the lake shore and by aerial spraying of insecticide in the Lambwe Valley. The incidence and geographical distribution of cases of T. rhodesiense sleeping sickness in the Lambwe Valley are described in this report. Eight survey areas were studied between June 1968 and August 1970. Three types of survey procedure were adopted and blood samples were taken for examination. The most reliable method of demonstrating trypanosomes was by direct microscopy of stained blood films. Cases were treated with either suramin or melarsoprol, the latter being preferred for long-standing infections, but a course of suramin was given first. Although there were localized foci of infection in the study area, cases occurred sporadically, usually in April, i.e., in the early part of the long rainy season. It is suggested that, for diagnosis, survey teams should be replaced by a few fixed diagnostic microscopy centres.