Remember avian influenza? The deadly version of flu that passes from poultry to humans and has caused outbreaks in many nations, most notably China. While we were dealing with Ebola panic and now a severe seasonal influenza outbreak, these viruses continued to spread (despite the lack of headlines).
The latest version of avian influenza to generate concern is H7N9 which has infected about 500 people since March of 2013, killing one-third. Taiwan has had 4 imported cases. The virus is spread to humans through direct and indirect contact with poultry. Limited human-to-human spread may also occur.
Because of the connection with poultry, control measures are centered around delimiting exposure to potentially infected birds. This often involves closing markets, culling, and inspections.
An ongoing dilemma in Hong Kong involved a plan to inspect all local chickens at a small checkpoint while the market is disinfected after a culling of close to 20000 birds because of the potential for H7N9's presence given imports from a mainland farm tested positive for the virus. This arrangement was not found to the liking of the farmers who believe it will prove too onerous for them to conduct business.
Their response was to threaten to release 5000 live chickens into the busiest streets of Hong Kong. Not only would that action cause a major calamity but if any of the birds are harboring H7N9 (or other avian influenza viruses that can infect humans) could potentially widen exposure which is traditionally restricted to market-goers. They have since rescinded the threat.
This incident illustrates why infectious diseases are so important. In just this one snapshot, you see economics, commerce, trade, government, and healthcare all intermingled. The ripple effect of certain infectious disease can be far-reaching and touch on virtually all aspects of modern civilization.
Sir William Osler once remarked that to know syphilis--which has the ability to cause disease in every organ system--is to know medicine; similarly, to know infectious disease is to know the world.