Association of helminth infection with decreased reticulocyte counts and hemoglobin concentration in Thai falciparum malaria

Following a study showing an association between Ascaris and protection fro m cerebral malaria, we conducted a cross-sectional study comparing admissio n hemoglobin concentrations in relation to exposure to helminth infection i n 2 separate groups of patients: 111 cerebral malaria cases and 180 mild Pl asmodium falciparum malaria cases. Hookworm infections were excluded. Mean hemoglobin concentrations were significantly lower in helminth-infected pat ients compared to those without helminths, both in the cerebral malaria gro up (10.1 +/- 3 [n = 47] versus 11.2 +/- 2.4 g/dl [n = 64], P = 0.04) and th e mild malaria group (11 +/- 2.5 [n = 89] vs 12.2 +/- 2.7 g/dl [n = 91], P = 0.004). Median reticulocyte counts, only available in the cerebral malari a group, were lower in helminth-infected patients compared to those without helminths (15,340/23,760 per mul, P = 0.03). Adjustments for confounders s uch as body mass index did not alter these associations. These data are con sistent with a mechanism causing anemia linked to differences in the immune response of helminth-infected patients during malaria.