The Type A convalescent sera were a subset from a total of 59 subjects with tularemia reported on Martha's Vineyard between 2000 and 2006. Approximately 60% of cases were thought to be due to inhalation of the bacterium (Feldman et al., 2003 and Matyas et al., 2007). In this study, sera from the first physician visit were available from 12 confirmed Type A tularemia patients.