Studies on the metabolism of B12 and folic acid were performed in patients with heavy hookworm infection and severe iron deficiency anemia, and in patients with light infection, noninfected patients and normal subjects.

Patients with heavy hookworm infection showed a marked decrease of the serum B12 as compared with normal subjects. Eight of 21 cases studied showed values of serum B12 below 100 µµg./ml.

Twelve of 13 patients with severe hookworm infection showed impairment of the pteroylglutamic acid intestinal absorption; however, none of them exhibited megaloblastic proliferation in the bone marrow. They all recovered with iron therapy alone. The patients with light infection and the noninfected patients with iron deficiency anemia did not demonstrate significant differences from the normal subjects studied.