It is implemented in the new Virtual Campus Authentication System One (LDAP)

In late February 2012 the team of the Virtual Campus of Public Health implemented a singleauthentication service that allows users to access all sites and classrooms with a single user account.

So if you have an account created in the Portal Regional, Regional or  Countries Virtual Classroom may enter the same username and password. Additionally the user account onthe Virtual Classroom PAHO Staff can access other sites with your account of PAHO.

On this graph you can see how the user interacts with the authentication server: