This interactive graphic gives a general visual idea of the way an infectious disease can spread around the world, reflecting transmission between people locally and extended by extensive international travel. It can be modified to give an idea of the severity, rapidity and extent of infection. For example, very provisional data for the current H1N1 swine flu pandemic suggests it could infect up to a third of the population, and cause deaths in up to 0.4 per cent of cases.

WARNING: This is not a predictive tool. It was created by the FT graphics department and is not based on any epidemiological model of a particular disease. It cannot show the precise pattern of spread or the relative risk of exposure in a particular location, and does not take into account specific factors that may affect disease, such as the effect of other infections in people, nutrition, genetic factors, the mechanisms of transmission, or medical support and quarantining. It does highlight the speed with which infection can spread globally in the 21st century.