The administrative/clinical core will provide administrative and infrastructure support for all four ICIDR projects, for the virology core and for the Fogarty ABC program. Dr. Mertz, the ICIDR Director will serve as core leader, with the assistance of Dr. Vial, the Major Foreign Collaborator; the lead research nurse/program manager, and other staff at CU. Dr. Vial will be administratively responsible for all projects within Chile, including those in the Ministry. Dr. Belmar will lead a workgroup within the Ministry of Health to ensure that each Ministry component (Environment, the Institute of Public Health (ISP), Epidemiology, and each regional health service) interacts effectively to support the overall objectives the research projects, the virology core and the Fogarty ABC program. Dr. Mertz will also lead a senior advisory group (SAG) that will provide overall direction for the projects, the virology core, and the Fogarty ABC training program. Three clinical research groups will be established in 1) the Medical Research Center of Catholic University in Santiago Chile, 2) the Coyhaique Regional Hospital and Region XI Health Service in Coyhaique, and 3) the Temuco Regional Hospital and Region IX, South Health Service in Temuco, Chile. Each will have a physician director and a research nurse to support the clinical research studies described in Projects 2, 3 and 4. The administrative units shall be responsible for entry of patients into clinical studies, completion of case record forms, and collection, processing and shipment of clinical samples in support of projects 2, 3, and 4. Data entry, regulatory affairs, field monitoring and quality assurance will be the primary responsibility of the lead research nurse based with Dr. Vial at the Center for Medical Research in Santiago. Interrelated databases will be established for clinical, clinical trial, epidemiology, rodent, GIS, virology, and HLA data sets. Via the internet each research group and Fogarty trainees will have electronic access to data bases maintained by each research component and will have the ability to access data. Different levels of data access will be controlled by passwords. Dr. Weiss will lead an Information Management Advisory Group (IMAG) that will be responsible for development of the databases and the access between databases. Using the clinical databases, the UNM clinical database supported by the EVRG program, and data from placebo-treated subjects in the CASG and ICIDR treatment studies, Dr. Mertz and others will describe, compare and contrast the clinical course of Andes- and Sin Nombre-associated HCPS.