Among the species negatively associated with typhoid fever in Malawi only was Ruminococcus gnavus, which could influence susceptibility to enteric infection via IgA stimulation [14], protect against enteropathogenic E. coli [41], stimulate host tryptophan catabolism [28] (S. Typhi requires tryptophan to grow in macrophages [11]) and produce secondary bile acids including chenodeoxycholic acid and iso-LCA that have anti-virulence effects on Salmonella [35, 66]. Here, CD79A is linked to typhoid fever.