Infant anemia is associated with reduced TLR-stimulated cytokine responses and increased nasopharyngeal colonization with Moxarella catarrhalis.

Anemia is a major public health problem in young children. Reports on the role of anemia on infectious diseases remained controversial. We aim to investigate the effect of anemia on innate immunity, nasopharyngeal bacterial colonization, and subsequent infectious outcome. Blood tests were examined at the age of 12 months. TLR-induced cytokine production was assessed by ELISA. Bacteria from nasopharyngeal specimens were identified with traditional culture. Clinical infectious diseases were followed yearly until 3 years of age. Result showed that of the 423 infants, 72 had hemoglobin level ≤ 11 g/dL, among which 55% had normal iron level. There was significant association between hemoglobin level and TLR1-2, and 4 induced IL-6 (p = 0.04, 0.02) and that of TLR4 stimulated TNF-α response (p = 0.04). Children with anemia had higher nasopharyngeal colonization with Moxarella catarrhalis. Clinical analysis did not show anemia to be associated with infectious morbidity. However, children who developed LRTIs had mean lower ferritin levels. We speculated that iron might be the key factor related to infectious morbidity. Thus, to investigate the role of anemia in infectious diseases, it is important to first consider the prevalence of iron deficit, since the incidence of iron deficiency-induced anemia may vary among different regions.