IgM and antibody measurement in the diagnosis and management of Gambian trypanosomiasis.

Serum and cerebrospinal fluid (CSF) IgM were measured in 182 patients at various stages of Gambian sleeping sickness and correlated with antibody levels measured by enzyme-linked immunosorbent assay (ELISA). Each of these tests in serum gave a 30% false negative result, but when both were used this fell to 12%. Measurements of IgM in CSF were raised in 87% of patients with advanced disease and in none of the early cases. The IgM levels fell slowly to normal by 12 months after treatment. A high level at this time, or a rise after treatment, was helpful in diagnosing relapsed patients. Antibody levels in CSF were of no use in diagnosis or prognosis, and were raised in many controls.