Surveillance and compartmentalisation as a tool to control avian influenza

Surveillance for avian influenza can have several objectives. Generally, these are to detect the presence of infection or to declare disease freedom. Claims for disease freedom can refer to an entire country, a zone within a country, or a compartment. Disease freedom cannot be demonstrated absolutely; however, through a multi-pronged approach employing different surveillance strategies, sufficient confidence in the absence of infection can be achieved. The recently developed OIE guidelines for surveillance for avian influenza offer different approaches to meet these goals. The guidelines are not intended to be prescriptive but rather offer options that countries may apply depending on their epidemiological situation. Compartmentalisation is a new concept that allows the recognition of populations of different health status based on management as opposed to geographic factors (regionalisation). A proposed approach for the application of this novel concept is presented.