Here, we show that even low doses (~2 × 102 CFUs/mouse) of an attenuated strain of S. typhimurium (29, 31) can cause a disseminated disease in MyD88−/− mice, as detected by shedding of bacteria in their stools, splenomegaly, and significantly elevated bacterial burden in spleen and liver compared to MyD88+/+ mice. The gene discussed is MYD88; the disease is Splenomegaly.