TLR4 and Legionnaires' disease: Regarding the type of infection, it is interesting to note that the two SNPs in TLR4 which we found associated with resistance to TB were reported to be associated with resistance to Legionnaires' disease [38] (caused by infection with Legionella pneumophila, an intracellular Gram-negative bacterium) and to be associated with a protective effect against leprosy caused by Mycobacterium leprae [39].