Cerebrospinal fluid neopterin as marker of the meningo-encephalitic stage of Trypanosoma brucei gambiense sleeping sickness.

BACKGROUND: Sleeping sickness, or human African trypanosomiasis (HAT), is a protozoan disease that affects rural communities in sub-Saharan Africa. Determination of the disease stage, essential for correct treatment, represents a key issue in the management of patients. In the present study we evaluated the potential of CXCL10, CXCL13, ICAM-1, VCAM-1, MMP-9, B2MG, neopterin and IgM to complement current methods for staging Trypanosoma brucei gambiense patients. METHODS AND FINDINGS: Five hundred and twelve T. b. gambiense HAT patients originated from Angola, Chad and the Democratic Republic of the Congo (D.R.C.). Their classification as stage 2 (S2) was based on the number of white blood cells (WBC) (>5/µL) or presence of parasites in the cerebrospinal fluid (CSF). The CSF concentration of the eight markers was first measured on a training cohort encompassing 100 patients (44 S1 and 56 S2). IgM and neopterin were the best in discriminating between the two stages of disease with 86.4% and 84.1% specificity respectively, at 100% sensitivity. When a validation cohort (412 patients) was tested, neopterin (14.3 nmol/L) correctly classified 88% of S1 and S2 patients, confirming its high staging power. On this second cohort, neopterin also predicted both the presence of parasites, and of neurological signs, with the same ability as IgM and WBC, the current reference for staging. CONCLUSIONS: This study has demonstrated that neopterin is an excellent biomarker for staging T. b. gambiense HAT patients. A rapid diagnostic test for detecting this metabolite in CSF could help in more accurate stage determination

Detailed description of false negative patients obtained according to neopterin and IgM after removal of early–late stage patients from S2 group.

<p>FN: false negatives.</p

Description of the training and the validation cohorts.

*<p>Fisher’s exact test: training cohort, non significant differences; validation cohort, p value  = 0.0133.</p>†<p>Mann-Whitney <i>U</i> test: training and validation cohort, non significant differences.</p>‡<p>Information not available for one patient.</p><p>||NA: not available information.</p><p>Stage was defined according to WHO guidelines.</p

Results obtained for IgM and neopterin on the validation cohort after application of the cut-off calculated on the training cohort and removal of early-late stage patients (n = 41).

<p>95%CI = 95% confidence interval; SP%  =  specificity %; SE%  =  sensitivity %.</p><p>Early-late stage patients (n = 41), i.e. patients having CSF WBC/µL ≤5 and presence of parasites in CSF (n = 4) or patients having 5</p

Results obtained for the eight markers assessed on the training cohort.

<p>Training cohort (n = 100): Stage 1 n = 44; Stage 2 n = 56. Early-late stage patients were not included.</p>*<p>Sensitivity was set to 100%.</p>†<p>Mann-Whitney <i>U</i> test.</p><p>95%CI = 95% confidence interval; SP%  =  specificity %; SE%  =  sensitivity %.</p><p>The reported cut-off and SP% correspond to 100% SE.</p

Results obtained for IgM and neopterin on the validation cohort after application of the cut-off calculated on the training cohort.

<p>Validation cohort (n = 412): Stage 1 n = 184; Stage 2 n = 228. Early-late stage patients are included in S2 group.</p>*<p>Mann-Whitney <i>U</i> test.</p

Ability of WBC, IgM and neopterin in discriminating between patients without or with parasites in CSF.

<p>T−: patients without evidence of parasite in CSF (n = 245); T+: patients with parasite detected in CSF (n = 166). Missing information for 1 S2 patient.</p><p>95%CI = 95% confidence interval; SP%  =  specificity %; SE%  =  sensitivity %.</p

Ability of WBC, IgM and neopterin in discriminating between patients without or with neurological signs.

<p>NS−: patients without neurological signs (n = 181); NS+: patients with neurological signs (n = 222). Missing information for 9 patients.</p><p>95%CI = 95% confidence interval; SP%  =  specificity %; SE%  =  sensitivity %.</p