EPO and infection: Similarly, low levels of the erythropoiesis-stimulating cytokine EPO were not responsible; on the contrary, serum EPO levels actually increased during the infection, consistent with the higher EPO levels observed after infection of mice with P. chabaudi (Chang and Stevenson, 2004) and in several human studies examining patients with P. falciparum anemia (Burchard et al., 1995; Verhoef et al., 2002).