There are several reasons that you might find the need to separate yourself from the rest of the population.
Pandemic is one that worries me the most. Specifically, a flu pandemic worries me because the flu seems pretty common, and certain strains can be deadly.
When the next Pandemic emerges:
History is the best teacher. Take the 20th century, for example. The Spanish Flu Pandemic of 1918 was said to have killed close to 50 million worldwide. That number included over 625,000 in the United States. The first cases in the US were at an Army base in my home state of Kansas on March 11th, 1918. It started as a trickle. By the end of the first week almost 500 soldiers had fallen sick. During the year, the flu killed close to 60,000 American soldiers.
At first it was known as the “3-day fever” and the symptoms looked like any other case of the flu. Coughing, chills, vomiting, and high fever were its calling card. But then brown spots started to appear on cheeks, and then bloody fluid would take over the lungs. Death from suffocation would soon follow.
In 2005, researchers finally figured out what made the 1918 flu so deadly and where it came from. It is now known as H1N1. It was an avian strain of the flu that developed the ability to cross over from birds to humans. There have been two other pandemics caused by flu viruses since 1918. In 1957 and 1958 the Asian flu killed close to 70,000 and then a decade later the Hong Kong flu killed 35,000 Americans.
Where is the next one going to come from? The best guess is H5N1 another strain of Avian flu. While it has not yet developed the ability to spread from person to person, many researchers believe that it could in time. H1N1 and other strains of flu make the news every year precisely because they are a potential threat.