Putative biomarkers of environmental enteric disease fail to correlate in a cross-sectional study in two study sites in Sub-Saharan Africa

Environmental enteric dysfunction (EED) is an elusive, inflammatory syndrome of the small intestine thought to be associated with enterocyte loss and gut leakiness and lead to stunted child growth. To date, the gold standard for diagnosis is small intestine biopsy followed by histology. Several putative biomarkers for EED have been proposed and are widely used in the field. Here, we assessed in a cross-sectional study of children aged 2-5 years for a large set of biomarkers including markers of protein exudation (duodenal and fecal alpha-1-antitrypsin (AAT)), inflammation (duodenal and fecal calprotectin, duodenal, fecal and blood immunoglobulins, blood cytokines, C-reactive protein (CRP)), gut permeability (endocab, lactulose-mannitol ratio), enterocyte mass (citrulline) and general nutritional status (branched-chain amino acids (BCAA), insulin-like growth factor) in a group of 804 children in two Sub-Saharan countries. We correlated these markers with each other and with anemia in stunted and non-stunted children. AAT and calprotectin, CRP and citrulline and citrulline and BCAA correlated with each other. Furthermore, BCAA, citrulline, ferritin, fecal calprotectin and CRP levels were correlated with hemoglobin levels. Our results show that while several of the biomarkers are associated with anemia, there is little correlation between the different biomarkers. Better biomarkers and a better definition of EED are thus urgently needed

Activités biologiques et dynamique de la matière organique du sol sous systèmes de culture en semis direct sur couverture végétale (Hauts plateaux de Madagascar)

The objective of this study was to investigate the impact of soil management on soil biofunctioning in the highlands of Madagascar. Direct seeding Mulch-based Cropping systems (DMC) were compared to conventional tillage (CT) and the natural fallow (NF) on the rate of decomposition and mineralization of residues as well as on the abundance, biomass and activity of litter- and soilmicroorganisms and macrofauna. Long term experimentation was used in Bemasoandro and Andranomanelatra. Contrasted cropping systems were studied, DMC on crop residues and on living mulches, CT and the NF. Results showed that the NF soil had the highest C and N content, however DMCs increased microbial biomass, soil respiration and nutrient cycling except for urease activity which was very high in NF (P<0.05). Depending on biochemical quality of the inputs, the dynamics of OM is different in the different systems. Management influenced macrofauna density and biomass. This study shows that the CT was detrimental to soil biological quality. DMC is a good soil management alternative but its effects on soil biofonctions depend on the choice of crops, crop association or rotation and the quality and quantity of OM added to soil which regulating major soil processes and functions.L'impact du mode de gestion du sol sur son biofonctionnement a été étudié sur les hauts plateaux de Madagascar. Le semis direct sur couverture végétale (SCV) est comparé au labour traditionnel (LB) et à la jachère naturelle (JN) concernant la minéralisation des résidus, l'abondance et les activités des microorganismes et de la macrofaune de la litière et du sol. L’étude a été menée à Bemasoandro et Andranomanelatra sur des systèmes contrastés de longue durée, SCV sur résidus et couverture vive, LB et la JN. Le sol sous la JN a les teneurs en C et N les plus élevées. Mais les SCV augmentent la biomasse microbienne, la respiration du sol et certaines activités enzymatiques du sol plus que la JN (P <0.05). De plus les SCV améliorent la densité et la biomasse de la macrofaune. La dynamique de la MO diffère dans les différents systèmes selon la qualité biochimique des entrées. Le LB diminue la qualité biologique du sol. Le SCV est une bonne alternative de gestion du sol mais ses effets sur le biofonctionnement varient selon le choix des cultures, de leurs associations et rotations déterminant la qualité et quantité de MO apportée, elle-même régulatrice du biofonctionnement du sol