We are looking for healthy adult subjects 18 years or older who do not have any chronic medical problems, who are not taking medications that suppress the immune system, who are not pregnant, and who have a history of dengue infection. We are doing this study in order to understand the immune responses following dengue infection. Participation in this study involves providing a blood sample. Compensation is provided. Please contact Jaclyn at (508) 856-5472 or Jaclyn.firstname.lastname@example.org.