Of the seven specimens showing a mixed infection three were diagnosed by the tpi assemblage-specific PCR (whereas they were typed as B at both the bg and gdh loci), three were typed as B at the tpi locus but as A at the gdh locus (two specimens) or at the bg locus (one specimen), and one was typed as A at the bg locus but as B at the gdh locus. This evidence concerns the gene TPI1 and infection.