In Trichinella spiralis and influenza co-infected mice, the influenza virus-induced secretion of the lung-damaging tumour necrosis factor alpha is modulated, as described by Furze et al. in a recent study. However, the immune response induced by T. spiralis is so variable that this modulation could be of limited value to manage clinical cases of influenza. Nevertheless, the concept that parasites can modulate influenza-induced pathology presents an interesting and potentially useful approach to therapeutics. The local perturbations induced by T. spiralis migration, coincident with the site of influenza infection, certainly warrant further studies.