 The objectives of this two-part, primary immunization and booster dose, study are to continue to collect safety data on Rift Valley Fever RVF Vaccine, Inactivated TSI-GSD 200; and, to continue to collect immunogenicity data on Rift Valley Fever RVF Vaccine, Inactivated TSI-GSD 200 and analyze interim data to determine whether a 6-month dose is indicated; and, to provide potential protection for personnel at risk for occupational exposure to the RVF virus and collect data on incidence of occupational RVF infection subclinical and clinical in immunized personnel. 