Very few granulomas containing developing worms at days 12 and 17 post Hb infection (1 out of 9 in the HbTg infected group 17 days post-infection and 4 out of 43 in the Hb infected group 12 days post-infection) were observed, suggesting that differences in worm infection kinetics were not responsible for the differences in worm burden observed between the two groups (Fig 1C). This evidence concerns the gene GSTM1 and infection.