Social Capital
In China, panic about the swine flu epidemic has led to the installation of temperature-detecting screens in airports. People entering from the West are screened and, if their temperature is elevated, they are quarantined.
India has also instituted a quarantine for sick Western visitors, but their system is more honor code than hi-tech. Visitors are expected to declare themselves if they suffer from flu symptoms. Somehow, I think fear of the inconvenience of quarantine far outweighs the desire to be a good global citizen for most travelers, however.