Assessment of central nervous system involvement in gambiense trypanosomiasis: value of the cerebro-spinal white cell count

OBJECTIVE To assess, in a clinical setting, the comparative values of conventional criteria used in the diagnosis of central nervous system (CNS) involvement in Trypanosoma brucei gambiense sleeping sickness: white cell count (WCC) in cerebrospinal fluid (CSF) > 5 x 10(6) cells/l; total protein concentration in CSF > 10 mg/100 ml); evidence of trypanosomes in CSF following double centrifugation (DC). METHOD In vitro culture of CSF was used as the gold standard. RESULTS The study showed that WCC is,by itself, as sensitive for the diagnosis of the CNS involvement as the usually recommended combination of three conventional criteria. The specificity of WCC is improved while the sensitivity is reduced when the cut-off point is set at a higher value (WCC > 10 x 10(6)/l). CONCLUSION In poorly equiped laboratories, the diagnosis of CNS involvement in patients with confirmed systemic infection should be based only on the WCC. However, a pilot study is needed to assess the feasibility and reliability of the WCC handled by 'front line' personnel, for different cut-off values.