By screening samples from febrile children using expression microarrays, Herberg et al. 16 found two genes with different expression levels depending on the nature of the causative pathogen: Interferon Induced Protein 44 Like (IFI44L) gene is up-regulated in viral febrile children and, in contrast, Family with Sequence Similarity 89 Member A (FAM89A) gene has elevated expression in febrile children with bacterial infection. Here, IFI44L is linked to bacterial infectious disease.