The benefits of the PCR-its/filter paper in the diagnosis of parasites and chemoresistant trypanosomes

The most reliable diagnosis method of animal trypanosomoses often used is the microscopic examination for motile trypanosomes. However, the sensitivity of this method remains relatively lower than the classic PCR (Polymerase Chain Reaction). This latter, besides of its high cost, requires some conditions which sometimes are difficult to apply on the field (conservation of samples at +4°C or -20°C). In this study, buffy coat (BCT) specimens were dotted on the filter paper and conserved during 12 months (September 2004 - October 2005) at ambient temperature until their treatment with Chelex® 5%. Samples were tested using unique “pantrypanosomique” PCR with ITS (Internal Transcribed Spacer) primers. This PCR using polyspecific primers indicated parasitological prevalences of 1.2 to 6.2 times higher than those recorded by the microscopic analysis of the buffy coat on the same samples. Beside the mixed infections which could be detected by one PCR reaction, this method could also distinguish Trypanosoma congolense savanna type from Trypanosoma congolense forest type. The gain of sensitivity and the easy conservation of samples in this method could be used for the detection of the  chemoresistance in low parasitological prevalence areas.