TPI1 and infection: Meanwhile, sequence analysis of the tpi gene identified assemblage C in three identical G. duodenalis-positive specimens, indicative of mixed infection with assemblages B and C. The increasing use of multilocus genotyping tools in epidemiological studies of G. duodenalis has led to more cases of mixed infections involving different assemblages being found in humans and animals [e.g., assemblages A and B (n = 15) in 54 G.