The objective of this Core is to coordinate and perform the collection of biological specimens from patients enrolled in the cohort populations from Projects 1, 2, and 3. This core will be responsible for the initial enrollment of the study individuals and the subsequent sample collection. This Core will be sampling the population living in Pampas de San Juan de Miraflores. This area is censured with a population of 40,000 and has an ongoing nutritional and demographic surveillance program. Using a single field area for Projects 1, 2, and 3 optimizes the utilization of human and physical resources, enhancing the overall efficiency of the program. The technical coordination and electronic filing of the activities of this Core will be performed at Asoclacion Benefica PRISMA. Samples collected will be sent to Verastegui's Core on the same day in which they are collected. Data obtained from the enrolled individuals and collected samples will be stored in palm top computers that have been programmed with data entry on screen software. This information will be forwarded to the respective Projects and to Cordera's Core for statistical and epidemiological analysis.