AUTHOR=Starck Tim , Dambach Peter , Rouamba Toussaint , Tinto Halidou , Osier Faith , Oldenburg Catherine E. , Adam Maya , Bärnighausen Till , Jaenisch Thomas , Bulstra Caroline A. 

TITLE=The effect of malaria on childhood anemia in a quasi-experimental study of 7,384 twins from 23 Sub-Saharan African countries

JOURNAL=Frontiers in Public Health

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2022.1009865

DOI=10.3389/fpubh.2022.1009865

ISSN=2296-2565

ABSTRACT=Background
Young children in sub-Saharan Africa (SSA), particularly those from resource-limited settings, are heavily burdened by anaemia and malaria. While malaria infected children frequently become anaemic (haemoglobin < 110g/L), anaemia is a strongly multifactorial disease with many other risk factors than malaria. Due to the complex and often overlapping contributors to anaemia, it remains challenging to isolate the true impact of malaria on population level haemoglobin concentrations. 
Methods
We quantified the malaria-induced effect on haemoglobin levels in children under 5 years of age, leveraging data from 7384 twins and other multiples, aged 6 to 59 months, from 57 nationally representative Demographic and Health Surveys (DHSs) from 23 SSA countries from 2006 to 2019. The quasi-experimental twin fixed-effect design let us minimize the impact of potential confounders that do not vary between twins. 
Results
Our analyses of twins revealed a malaria-induced haemoglobin decrease in infected twins of -9 g/L (95% CI -10; -7, p < 0.001). The relative risk of severe anaemia was higher (RR = 3.01 , 95% CI 1.79; 5.1, p < 0.001) among malaria positive children, compared to malaria negative children. Conversely, malaria positive children are only half as likely to be non-anaemic (RR = 0.51, 95% CI 0.43; 0.61, p < 0.001).
Conclusion
Even after rigorous control for confounding through a twin focussed study design, malaria substantially decreased haemoglobin levels among SSA twins, rendering them much more susceptible to severe anaemia. This effect reflects the population-level effect of malaria on anaemia.