This study examines the virtual infrastructures of the regional Latin American and Caribbean Health Sciences System (BIREME )based in Brazil. BIREME offers a regional health information system for collaboration in scientific research, education, and evidence-based health care. Virtual infrastructures refer to an environment characterized by overlapping distribution networks accessible through Internet portals and websites designed to facilitate integrated use of available resources. The objective of this paper is to identify open source system design and scalability at the regional level of analysis using theoretical perspectives from institutional economics and knowledge ecology. Qualitative case analysis reveals patterns of linkage among national and regional health information systems including emerging roles of social media in system integration. The social medicine ideology shared among countries of the Latin American region serves as a foundation for the principles of open access to health information and research, and open source software for development of scalable infrastructures.