Evaluation of a rapid screening test for sleeping sickness. Lumbala C, Bisser S, Nguertoum E, Flevaud L, Jacquet D, Büscher P, Biéler S, Ndung u JM

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1 Evaluation of a rapid screening test for sleeping sickness Lumbala C, Bisser S, Nguertoum E, Flevaud L, Jacquet D, Büscher P, Biéler S, Ndung u JM 1

2 Performance evaluation of prototype in the field Prototype co-developed by Standard Diagnostics, Inc. and FIND Kit components C 2 1 Control band Band 1: LiTat 1.3 VSG Band 2: LiTat 1.5 VSG Stable for at least 25 months at 40 C, or at least 5 weeks at 55 C. 2

3 Performing the RDT for HAT 3

4 Evaluation studies Objective: to determine the sensitivity and specificity of the RDT in comparison with CATT 3 countries: Angola, Democratic Republic of Congo (DRC) and Central African Republic (CAR) In DRC, participants were enrolled actively (Tshilenge MT) and passively (CS Tshibila) in East Kasai province Target sample size: 235 controls (no history of HAT and parasitologically negative) and 235 HAT cases (CI of 95% and power of 80%, and expected sensitivity and specificity of 95% for both the CATT1:8 and RDT) A blinding code was given to each participant, and CATT and RDT were performed by 2 independent lab technicians 4

5 Evaluation studies Active and passive screening: Finger prick blood Perform RDT & CATT on whole blood CATT +ve, RDT +ve (all) CATT +ve, RDT -ve (all) CATT -ve, RDT +ve (all) CATT -ve, RDT -ve (at least 235) Take venous blood Take venous blood Take venous blood Take venous blood +ve CATT titration -ve +ve CATT titration -ve GP *, CTC & maect GP *, CTC & maect GP *, CTC & maect GP*, CTC & maect GP *, CTC & maect GP *, CTC & maect -ve PCR & LAMP -ve -ve -ve -ve PCR & LAMP PCR & LAMP PCR & LAMP PCR & LAMP Studies in Angola, DRC and CAR * GP (gland puncture) performed only if typical swollen cervical lymph nodes are found. 5

6 Population screened and HAT cases identified in Angola, DRC and CAR Population screened: CAR % % % Angola Prevalence (HAT cases confirmed by microscopy) DRC 2.5% 2.0% Cases: 149 Angola 21 14% 1.5% 1.0% 0.5% 0.0% 0.30% Angola 1.20% DRC 2.13% CAR 1.01% Total CAR 77 52% 51 34% DRC

7 Enrolment of participants (DRC) Active screening Passive screening Total Screened population ml blood collected Cases (prevalence) 25 (0.64%) 26 (7.2%) 51 (1.2%) - Stage Stage 2 (stage 2/1 ratio ) 9 (0.64) 25 (25) 34 (2.26) - Unknown stage Controls

8 Results (DRC) True positive True negative Active S Passive S Total Active S Passive S Total CATT WB CATT 1: CATT 1: RDT both bands RDT band RDT band CRS + (THA+) CRS (THA-) Active S Passive S Total Active S Passive S Total Total

9 Specificity: DRC study Controls: all individuals screened with RDT and CATT (excluding current and past confirmed HAT cases) N=4178 Upper 95% CI Specificity (%) Lower 95% CI % 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% CATT whole blood CATT 1:4 CATT 1:8 RDT both bands RDT band 1 RDT band 2 Error bars: 95% confidence interval 9

10 Sensitivity: DRC study Based on 51 parasitologically confirmed HAT cases Upper 95% CI Sensitivity (%) Lower 95% CI % 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% CATT whole blood CATT 1:4 CATT 1:8 RDT both bands RDT band 1 RDT band 2 Error bars: 95% confidence interval 10

11 Sensitivity: DRC study (2) Based on 51 parasitologically confirmed HAT cases Case ID CATT whole blood CATT dilutions 1:8 RDT Last +ve dilution 1 and/or D1 to D38 Pos Pos Pos Pos Pos D39 Pos Pos 1:8 Neg 0 0 D40 Pos Pos 1:64 Pos 0 2+ D41 Pos Neg 1:4 Neg 0 0 D42 Pos Pos 1:32 Pos 0 3+ D43 Pos Pos 1:64 Neg 0 0 D44 Pos Neg 1:4 Pos D45 Pos Pos 1:8 Neg 0 0 D46 Pos Neg 1:4 Pos D47 Pos Neg 1:4 Neg 0 0 D48 Neg Neg N/A Pos D49 Pos Pos 1:16 Pos 2+ 0 D50 Pos Pos 1:8 Pos 1+ 0 D51 Pos Neg 1:4 Pos Total Two antigens on the RDT are necessary to achieve good sensitivity (some cases are missed by antigen 1 but not by antigen 2, and the opposite). Although the sensitivity of CATT1:8 is almost identical to the sensitivity of the RDT, some cases are picked up by CATT1:8 and not by the RDT, while for other cases, it is the opposite. 11

12 Sensitivity: 3 countries combined Based on 149 parasitologically confirmed HAT cases Sensitivity 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 94.0% 94.0% CATT whole blood CATT 1:4 89.3% 89.3% CATT 1:8 RDT both bands 85.9% 85.9% RDT band 1 RDT band 2 Error bars: 95% confidence interval The sensitivity of the RDT is the same as the sensitivity of CATT at dilution 1:8 (p=0.85) and not significantly lower than that of CATT on whole blood (p=0.21) 12

13 Specificity: 3 countries combined Controls: all individuals screened with RDT and CATT (excluding current and past confirmed HAT cases) - N= % 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 95.9% 96.6% 98.9% CATT whole blood CATT 1:4 Specificity CATT 1:8 94.6% 95.6% 95.1% RDT both bands RDT band 1 RDT band 2 Error bars: 95% confidence interval The specificity of the RDT is slightly lower than the specificity of CATT on whole blood (p<0.001), and lower than the specificity of CATT at dilution 1:8 (p<0.001) 13

14 Optimization of HAT RDT As part of the final product optimization after these studies, SD improved the sensitivity of the RDT further, without significantly impairing specificity. Sensitivity was assessed at SD using 49 stored samples from confirmed HAT cases (15 from Angola, 14 from DRC and 20 from CAR) 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Sensitivity 98.0% 87.8% Old RDT Optimized RDT Error bars: 95% confidence interval p=

15 Optimization of HAT RDT (cont.) Specificity was assessed on 399 controls during active screening in East Kasai, DRC. 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Specificity 94.0% 93.5% Old RDT Optimized RDT Error bars: 95% confidence interval p=

16 HAT RDT demonstration study Started in May 2013 in DRC Study sites: 4 fixed centres and 4 mobile teams in 3 provinces (Bandundu, East Kasaï and West Kasaï) Study objectives: 1. To determine the total cost of using the RDT and/or the CATT test as part of 4 different diagnostic algorithms 2. To determine the cost effectiveness of diagnosing and treating HAT patients using 4 different diagnostic algorithms including the RDT and/or the CATT test 3. To assess the ease of implementation of the RDT and of CATT. Status: Field activities have just been completed. Data entry in progress. 16

17 HAT RDT demonstration study The 4 diagnostic algorithms being evaluated CRS: composite reference standard (combination of routine parasitological tests) 17

18 Acknowledgements Specimens WHO, Switzerland ITM, Belgium NaLIRRI, Uganda Antigens Univ of Glasgow, UK Cambridge Univ, UK Leicester Univ, UK Univ of California, USA Univ of Texas, USA Inst of Cell Path, Belgium ITM, Belgium Univ of Geneva, Switzerland ILRI, Kenya Univ of Bordeaux, France Antigen screening MicroCoat, Germany RDT development Standard Diagnostics, South Korea Laboratory studies INT, Limoges, France ILRI, Kenya Makerere University, Uganda Clinical trials PNLTHA, DRC ICRA, CAR Institut Pasteur, CAR MSF, Spain INT, Limoges, France Enrolled participants, Angola, DRC & CAR Project management FIND Funding Bill & Melinda Gates Foundation, USA (through FIND) DFID, UK (through FIND) Governments of Angola, DRC & CAR Belgian Technical Cooperation (through PNLTHA, DRC) MSF, Spain