Survival of Francisella tularensis Type A in brackish-water

Martha’s Vineyard (MV), Massachusetts has been the location of two outbreaks of pneumonic tularemia; landscaping activities have been associated with risk, suggesting environmental inhalation exposure. We determined whether salinity or other components of brackish-water present in a location with endemic tularemia may prolong survival of F. tularensis. In addition, we demonstrate for the first time that F. tularensis Type A appears similar to Type B with respect to environmental stability. The results of this study suggest an explanation for why MV is the site of pneumonic tularemia transmission as opposed to sites in the southcentral USA, where tularemia is more commonly reported: Bacteria may be more prone to surviving in salt-influenced soil or moisture in the island setting.