American marines in Vietnam were shown to have megaloblastic changes in bone marrow aspirates and an inappropriate reticulocyte response to anemia associated with malaria. Convalescence was prolonged because of delayed correction of anemia. These patients had normal serum vitamin B-12 levels, reduced serum folic acid, and a reticulocyte response to “physiological” doses of folic or folinic acid. Nonmalaria patients had similar abnormalities. but with a reduced incidence. The cause of the folic acid deficiency is most likely multiple: 1) inadequate dietary folate, 2) reduced absorption of folic acid, 3) increased utilization of folic acid owing to the hemolysis and fever of malaria, and 4) drug inhibition by the antimalaria chemotherapy.
Department of Clinical Investigation, U.S. Naval Medical Research Unit 2, Taipei, Taiwan, Republic of China. Present address: London School of Hygiene and Tropical Medicine, Keppel and Gower Street, London, WC1.
Present address: U.S. Naval Hospital, Portsmouth, Virginia 23708.