TABLE 3.

Comparison of some test characteristics of methods generally employed for the diagnosis of HAT

Technology	Source or reference used to estimate parameters	Detection limit (parasites per ml of sample processed)	Sensitivity (%) (reported range)	Specificity (%) (reported range)	Avg processing time (excluding nucleic acid extraction)	Equipment needed	Estimated costs (€) (excluding labor costs)	Remarks
Microscopic examination of blood	6, 17; this study	1,000-10,000	57-100		20-30 min	Microscope and possibly concn equipment	1.00	Detection limit and test sensitivity and specificity can be enhanced by concn of parasites, but this will increase processing time and costs
Microscopic examination of CSF	6	Difficult to determine, because parasites tend to disintegrate after sample collection	86-100		30-60 min	Microscope and possibly concn equipment	1.00-3.00	Detection limit and test sensitivity and specificity can be enhanced by concn of parasites, but this will increase processing time and costs
Serology (card agglutination test for trypanosomiasis)	6, 11	Antibody test; not quantifiable	87-98	95	10 min	Agglutination card and materials for blood collection	1.00	Intended as a screening test for T. brucei gambiense only
PCR systems	4, 7, 13, 19	6-100	87-100	97-100	2-4 h	Real-time PCR machine or thermocycler, combined with ethidium bromide gel system or OC sticks	2.60-4.75	Costs range from those of standard PCR to those of quantitative real-time PCR; processing time depends on the readout system (gel electrophoresis vs real-time system)
NASBA systems	17, 23, 25	10-100	73-100	97-100	2 h	Water bath or heat block; real-time reader or ECL detection system	5.20	Costs of NASBA are higher due to costs of amplification reagents; cost estimate is based on use of a real-time NASBA assay
NASBA-OC	This study	10	73-89	100	90 min	Water bath or heat block; OC sticks	4.00-4.50	Costs are reduced because of the simplified readout system