After Fiji ceded to the British Empire, a royal party visited Australia as a gift from Queen Victoria. Arriving during a measles outbreak, the royal party brought the disease back to their island, and it was spread further by the tribal heads and police who met with them upon their return. Spreading quickly, the island was littered with corpses that were scavenged by wild animals, and entire villages died and were burned down, sometimes with the sick trapped inside the fires. One-third of Fiji’s population, a total of 40,000 people, died.
In an age of advanced medical technology and innovation, we can hardly imagine a time where the flu could be deadly. There are definitely still epidemics in our time, like for example the recent Ebola outbreak. However, the epidemics in the past involved far greater numbers of people.
Typhus fever is spread by lice. The war brought on poor sanitation that probably led to a higher density of lice and made the transmission more prevalent.
Typhus fever caused three million deaths in Russia alone.
As humans have spread across the world, so have infectious diseases. Even in this modern era, outbreaks are nearly constant, though not every outbreak reaches pandemic level as the COVID-19 has.
The original use of the word Quarantine was the act of anchoring a ship arrived in Venice, Italy, for 40 days before landing.
Infectiousness of any disease is measured by the reproduction number (R0, or R naught). For example, Smallpox has an R0 of 6 whereas Measles has an R0 of 16.
Vaccination, if available, and herd immunity can curb the spread of disease.
Big cities, with exploding population and traffic, can lead to the rapid spread of any infectious disease.
Epidemic is a term that is often broadly used to describe any problem that has grown out of control. An epidemic is defined as "an outbreak of a disease that occurs over a wide geographic area and affects an exceptionally high proportion of the population." An epidemic is an event in which a disease is actively spreading.