Compared to uninfected mice, the serum levels of GM-CSF in IOE-infected mice were increased by approximately 12 fold on day 5 p.i., and 20 fold on day 7 p.i. Infection of mice with E. muris induced higher levels of GM-CSF in serum (near 5-fold increase compared to uninfected controls) on day 5 p.i., however, GM-CSF levels decreased on day 7 p.i. (Fig. 3A). This evidence concerns the gene CSF2 and infection.