The synergistic effect of concomitant schistosomiasis, hookworm, and trichuris infections on children's anemia burden.
OBJECTIVE
To estimate the degree of synergism between helminth species in their combined effects on anemia.


METHODS
Quantitative egg counts using the Kato-Katz method were determined for Ascaris lumbricoides, hookworm, Trichuris trichiura, and Schistosoma japonicum in 507 school-age children from helminth-endemic villages in The Philippines. Infection intensity was defined in three categories: uninfected, low, or moderate/high (M+). Anemia was defined as hemoglobin <11 g/dL. Logistic regression models were used to estimate odds ratios (OR), 95% confidence intervals (CI), and synergy index for pairs of concurrent infections.


RESULTS
M+ co-infection of hookworm and S. japonicum (OR = 13.2, 95% CI: 3.82-45.5) and of hookworm and T. trichiura (OR = 5.34, 95% CI: 1.76-16.2) were associated with higher odds of anemia relative to children without respective M+ co-infections. For co-infections of hookworm and S. japonicum and of T. trichiura and hookworm, the estimated indices of synergy were 2.9 (95% CI: 1.1-4.6) and 1.4 (95% CI: 0.9-2.0), respectively.


CONCLUSIONS
Co-infections of hookworm and either S. japonicum or T. trichiura were associated with higher levels of anemia than would be expected if the effects of these species had only independent effects on anemia. This suggests that integrated anti-helminthic treatment programs with simultaneous deworming for S. japonicum and some geohelminths could yield a greater than additive benefit for reducing anemia in helminth-endemic regions.
Department of Community Health and International Health Institute, Brown University Providence, Rhode Island, USA. AEzeamama@healtheffects.org
Amara E
AE
Ezeamama
Stephen T
ST
McGarvey
Luz P
LP
Acosta
Sally
S
Zierler
Daria L
DL
Manalo
Hai-Wei
HW
Wu
Jonathan D
JD
Kurtis
Vincent
V
Mor
Remigio M
RM
Olveda
Jennifer F
JF
Friedman
D000293:Adolescent; D000740:Anemia / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology*; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006725:Hookworm Infections / Q000150:complications* / Q000453:epidemiology; D006801:Humans; D008297:Male; D012552:Schistosomiasis / Q000150:complications* / Q000453:epidemiology; D014257:Trichuriasis / Q000150:complications* / Q000453:epidemiology