Dot enzyme-linked immunosorbent assay for more reliable staging of patients with human African trypanosomiasis

Human African trypanosomiasis (HAT) or sleeping sickness is a disease characterized by a hemolymphatic stage I followed by a meningoencephalitic stage 2 which is fatal without specific treatment. Furthermore, due to the toxicity of drugs used to treat stage 2 (mainly melarsoprol) accurate staging is required. Actual criteria employed during field surveys are not sensitive enough for precise staging. Antineurofilament (anti-NF) and antigalactocerebrosides (anti-GaIC) antibodies have been identified in cerebrospinal fluid (CSF) as potential markers of central nervous system (CNS) involvement. We describe a dot enzyme-linked immunosorbent assay (dot-ELISA) to detect anti-GaIC and anti-NF antibodies and its value in staging. NF- and GaIC-dotted nitrocellulose strips were first developed in our laboratory. They were then evaluated in Angola and Central African Republic on 140 CSF samples. Compared to our staging criteria (i.e., CSF cell count >= 20 cells/mu l, CSF immunoglobulin M concentration >= 100 mg/liter, and/or the presence of trypanosomes in the CSF), combined detection of both CSF anti-NF and CSF anti-GaIC by dot-ELISA showed 83.2% sensitivity and 100.0% specificity. Dot-ELISA could be a useful test to diagnose CNS involvement in HAT in the less-equipped laboratories or in the field situation and to improve patient treatment.