http://www.who.int/ith/

It is addressed primarily to medical and public health professionals who provide health advice to travellers, but it is also intended to provide guidance to travel agents and organizers, airlines and shipping companies. Online book chapters include: Health risks and precautions, Travel by air, Environmental health risks; Accidents, injuries and violence; Infectious diseases; Vaccine-preventable diseases; Malaria; Blood transfusion. The site is also searchable by country and by disease