host-associated 65 animal host 64 digestive tract 63 intestine 62 mammalian host 62 human host 61 industrialized 46 infant 20 adult 16 elderly 10 terrestrial 5 built environment 4 anthropogenic 4 child 4 urban 2 full term birth 2 preterm birth 2 rural 2 plant host 1 aquatic 1 rhizosphere 1 rumen 1 adolescent 1 soil 1 marine 1 non-industrialized 1