Short answers, pulled from the story.
The scientific name of the measles virus is Morbillivirus. This airborne pathogen spreads with terrifying efficiency and can infect nine out of ten non-immune people who share a living space with an infected individual.
The measles virus diverged from its bovine ancestor rinderpest sometime between 1100 and 1200 AD. This divergence required a susceptible human population of over 500,000 people to sustain an epidemic, a demographic threshold not met until the growth of medieval European cities.
Maurice Hilleman at Merck produced the first successful measles vaccine, which became widely available in the United States in 1963. The vaccine was derived from the Edmonston strain, which John Enders and Thomas C. Peebles isolated from a 13-year-old boy named David Edmonston in 1954.
Measles was responsible for an estimated 2.6 million deaths in 1980 alone. Before the advent of vaccination, the disease was a leading cause of death worldwide and claimed millions of lives throughout recorded history.
Over 40,000 Fijians died during the 1875 measles outbreak, which represented approximately one-third of the population. This event is one of many historical tragedies where indigenous populations with no prior exposure to the virus suffered devastating mortality rates.