Mapping of positive PCR punches on FTA cards. The figure shows three diagrammatic representations of the repeated PCR of blood samples from zebu cattle. Each small circle or shape represents a punch taken for PCR analysis. The positions of each punch were recorded and the results for that PCR were related back to the position on the original sample. Key; open circle, negative PCR result; closed circle, T. theileri; closed triangle, T. brucei; closed square, T. congolense. Examples of a low, medium and high parasitaemia result are shown.