Effect of a+ -thalassaemia on episodes of fever due to malaria and other causes: a communitybased cohort study in Tanzania
Background It is controversial to what degree a+-thalassaemia protects against episodes of uncomplicated malaria and febrile disease due to infections other than Plasmodium. Methods In Tanzania, in children aged 6-60 months and height-for-age z-score <-1.5 SD (n = 612), rates of fevers due to malaria and other causes were compared between those with heterozygous or homozygotes a+-thalassaemia and those with a normal genotype, using Cox regression models that accounted for multiple events per child. Results The overall incidence of malaria was 3.0/child-year (1, 572/526 child-years); no differences were found in malaria rates between genotypes (hazard ratios, 95% CI: 0.93, 0.82-1.06 and 0.91, 0.73-1.14 for heterozygotes and homozygotes respectively, adjusted for baseline factors that were predictive for outcome). However, this association strongly depended on age: among children aged 6-17 months, those with a+-thalassaemia experienced episodes more frequently than those with a normal genotype (1.30, 1.02-1.65 and 1.15, 0.80-1.65 for heterozygotes and homozygotes respectively), whereas among their peers aged 18-60 months, a+-thalassaemia protected against malaria (0.80, 0.68-0.95 and 0.78, 0.60-1.03; p-value for interaction 0.001 and 0.10 for hetero- and homozygotes respectively). No effect was observed on non-malarial febrile episodes. Conclusions In this population, the association between a+-thalassaemia and malaria depends on age. Our data suggest that protection by a+-thalassaemia is conferred by more efficient acquisition of malaria-specific immunity
| Main Authors: | , , , , , , , |
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| Format: | Article/Letter to editor biblioteca |
| Language: | English |
| Subjects: | alpha-thalassemia, anemia, c-reactive protein, case definitions, children, clinical malaria, disease, endemic areas, morbidity, plasmodium-falciparum malaria, |
| Online Access: | https://research.wur.nl/en/publications/effect-of-a-thalassaemia-on-episodes-of-fever-due-to-malaria-and- |
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| Summary: | Background It is controversial to what degree a+-thalassaemia protects against episodes of uncomplicated malaria and febrile disease due to infections other than Plasmodium. Methods In Tanzania, in children aged 6-60 months and height-for-age z-score <-1.5 SD (n = 612), rates of fevers due to malaria and other causes were compared between those with heterozygous or homozygotes a+-thalassaemia and those with a normal genotype, using Cox regression models that accounted for multiple events per child. Results The overall incidence of malaria was 3.0/child-year (1, 572/526 child-years); no differences were found in malaria rates between genotypes (hazard ratios, 95% CI: 0.93, 0.82-1.06 and 0.91, 0.73-1.14 for heterozygotes and homozygotes respectively, adjusted for baseline factors that were predictive for outcome). However, this association strongly depended on age: among children aged 6-17 months, those with a+-thalassaemia experienced episodes more frequently than those with a normal genotype (1.30, 1.02-1.65 and 1.15, 0.80-1.65 for heterozygotes and homozygotes respectively), whereas among their peers aged 18-60 months, a+-thalassaemia protected against malaria (0.80, 0.68-0.95 and 0.78, 0.60-1.03; p-value for interaction 0.001 and 0.10 for hetero- and homozygotes respectively). No effect was observed on non-malarial febrile episodes. Conclusions In this population, the association between a+-thalassaemia and malaria depends on age. Our data suggest that protection by a+-thalassaemia is conferred by more efficient acquisition of malaria-specific immunity |
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