Schistosomiasis japonica, anemia, and iron status in children, adolescents, and young adults in Leyte, Philippines 1.
BACKGROUND
Observational and interventional evidence supports a relation between human schistosomiasis and anemia; however, the exact causal mechanisms remain unclear. Eggs translocating across the intestinal or bladder wall may result in extracorporeal blood loss with subsequent iron deficiency. Alternatively, anemia may result from cytokine-mediated dyserythropoiesis, as seen in anemia of inflammation.


OBJECTIVE
By evaluating the cross-sectional relation between the intensity of Schistosoma japonicum infection, hemoglobin concentration, and iron status in 7-30-y-old persons from S. japonicum-endemic rice-farming villages in the province of Leyte, Philippines, we assessed the relative contribution of iron deficiency and anemia of inflammation to schistosomiasis-associated anemia.


METHODS
We enrolled 627 S. japonicum-infected and 111 S. japonicum-uninfected persons. We obtained stool samples to quantify S. japonicum infection and venous blood samples for hemograms and measures of iron status and inflammation.


RESULTS
Intensity of S. japonicum infection was independently associated with hemoglobin (beta = -0.24; 95% CI: -0.31, -0.17). Persons with high-intensity infection had a greater risk of iron deficiency anemia (adjusted prevalence odds ratio: 6.6; 95% CI: 2.9, 14.7), but there was no evidence of this relation in low-intensity infections. In contrast, anemia without iron deficiency was prevalent across all intensities (adjusted prevalence odds ratio: 3.8; 95% CI: 1.5, 9.5).


CONCLUSIONS
Storage iron deficiency is a major contributor to anemia in high-intensity S. japonicum infection. A high prevalence of anemia without iron deficiency, exclusion of other mechanisms of anemia, and the evidence of low bioavailable iron suggest that anemia of inflammation contributes to S. japonicum-associated anemia at all infection intensities.
International Health Institute, Brown University, Providence, RI 02903, USA. tjalling_leenstra@brown.edu
Tjalling
T
Leenstra
Luz P
LP
Acosta
Gretchen C
GC
Langdon
Daria L
DL
Manalo
Li
L
Su
Remigio M
RM
Olveda
Stephen T
ST
McGarvey
Jonathan D
JD
Kurtis
Jennifer F
JF
Friedman
D000293:Adolescent; D000328:Adult; D000740:Anemia / Q000097:blood / Q000453:epidemiology* / Q000469:parasitology; D018798:Anemia, Iron-Deficiency / Q000097:blood / Q000453:epidemiology* / Q000469:parasitology; D002648:Child; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D019353:Endemic Diseases; D005243:Feces / Q000469:parasitology; D005260:Female; D006306:Health Surveys; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D008297:Male; D016017:Odds Ratio; D010270:Parasite Egg Count; D010679:Philippines / Q000453:epidemiology; D011990:Receptors, Transferrin / Q000097:blood; D012307:Risk Factors; D012554:Schistosomiasis japonica / Q000097:blood / Q000150:complications*; D016036:Seroepidemiologic Studies; D012720:Severity of Illness Index; D012923:Social Class
D006454:Hemoglobins; D011990:Receptors, Transferrin