Field evaluation of the CATT/Trypanosoma brucei gambiense on blood-impregnated filter papers for diagnosis of human African trypanosomiasis in southern Sudan.
Most Human African Trypanosomiasis (HAT) control programmes in areas endemic for Trypanosoma brucei gambiense rely on a strategy of active mass screening with the Card Agglutination Test for Trypanosomiasis (CATT)/T. b. gambiense. We evaluated the performance, stability and reproducibility of the CATT/T. b. gambiense on blood-impregnated filter papers (CATT-FP) in Kajo-Keji County, South-Sudan, where some areas are inaccessible to mobile teams. The CATT-FP was performed with a group of 100 people with a positive CATT on whole blood including 17 confirmed HAT patients and the results were compared with the CATT on plasma (CATT-P). The CATT-FP was repeated on impregnated filter papers stored at ambient and refrigerated temperature for 1, 3, 7 and 14 days. Another 82 patients with HAT, including 78 with a positive parasitology, were tested with the CATT-FP and duplicate filter paper samples were sent to a reference laboratory to assess reproducibility. The CATT-FP was positive in 90 of 99 patients with HAT (sensitivity: 91%). It was less sensitive than the CATT-P (mean dilution difference: -2.5). There was no significant loss of sensitivity after storage for up to 14 days both at ambient and cool temperature. Reproducibility of the CATT-FP was found to be excellent (kappa: 0.84). The CATT-FP can therefore be recommended as a screening test for HAT in areas where the use of CATT-P is not possible. Further studies on larger population samples in different endemic foci are still needed before the CATT-FP can be recommended for universal use.
Chappuis
F
F
Médecins Sans Frontières (MSF) - Switzerland, Geneva, Switzerland. francois.chappuis@hcuge.ch
Pittet
A
A
Bovier
P A
PA
Adams
K
K
Godineau
V
V
Hwang
S Y
SY
Magnus
E
E
Büscher
P
P
D000372:Agglutination Tests; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D001800:Blood Specimen Collection / Q000379:methods*; D005374:Filtration; D006801:Humans; D010209:Paper; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013397:Sudan; D014347:Trypanosoma brucei gambiense / Q000276:immunology*; D014353:Trypanosomiasis, African / Q000175:diagnosis*
D000913:Antibodies, Protozoan; D011933:Reagent Kits, Diagnostic