ICAO (2009) Guidelines for states concerning the management of communicable disease posing a serious public health risk. From: International Civil Aviation Organization. July 2009
http://www.icao.int/icao/en/med/AvInfluenza_guidelines.pdf. Accessed March 11, 2010  

These guidelines are written to assist States in developing an aviation related plan for any communicable disease posing a serious public health risk, such as an influenza virus with human pandemic potential. A preparedness plan for aviation is required since air travel may increase the rate at which a disease spreads, thereby decreasing the time available for preparing interventions. Although it is probably not feasible to
halt the spread of some diseases, advance preparation should make it possible to effect a delay and provide more time to prepare. Such preparation is necessary across many different sectors, including that of aviation. Any additional time to enable the production of an effective vaccine is likely to provide the best chance of mitigating the potential effects for a number of diseases that can be prevented by such a prophylactic measure.