Sensitivity analysis for multicopy target sequences. Lowest concentrations of trypanosome at which multicopy targets, 177 bp repeats (177) and internal transcribed spacer region (ITS) of ribosomal DNA, were reproducibly detected by PCR amplification. Absolute sensitivity (AS) equates to the number trypanosomes per mL of blood spotted onto the FTA filter, and effective sensitivity (ES) is the number of trypanosomes calculated per individual PCR. PCR= PCRs carried out on the specified number of washed discs. MDA= Multiple Displacement Amplification reactions carried out on the specified number of washed discs, and PCR undertaken using MDA product as template.