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Almost comparable in scale to the Black Death are the series of mostly smallpox outbreaks that occurred in the New World between 1492 and 18001850s, caused by Europeans bringing the disease to Native American populations that had no built immunity to this disease. The Aztecs are a famous example of an empire collapsing mostly because of smallpox devastating the population, but nearly every Native American populationspopulation, starting with the first populations that greeted Christopher Columbusand other explorers, experienced high death rates, some to the point of where they had nearly 100% fatalityrates. As a percentage of deaths, these outbreaks were probably the most devastating in history relative to the scale in which they occurred.<ref>For more on the smallpox outbreaks in the New World, see: Thornton, R., 1990. <i>American Indian holocaust and Survival ; a Population History Since 1492</i>, The Civilization of the American Indian Series. Univ. of Oklahoma Press, Norman, Okla.</ref>

The more recent flu pandemics are only recorded to be a major problem at global scales starting in the late 19th century. The so-called 'Russian Flu' started in Siberia and Kazakhstan in 1889 and likely killed nearly 400,000 in North America, Asia, Africa, and Europe. The so-called Spanish Flu, perhaps the most infamous until recently, in 1918 led to about 50 million deaths worldwide. It likely started in China, although it is not clear to this daywhat the origin of this flu was. The flu became evident as an outbreak in Madrid, which is why it was called the Spanish Flu as news services began to report it (Figure 2). It spread globally throughout 1918 and did not begin to disappear until 1919, likely fading because it had either killed those who were not immune to it or people developed immunity if they did not die from it. This pandemic was perhaps the first to travel so far and fast due to modern transport. The so-called Asian Flu in 1957 also led to a global-scale pandemic, but it was contained by 1958 after a vaccine had been developed. It was the first pandemic that was successfully contained after a vaccine had been derived, although it probably killed over a million people. One pandemic stands out among all these is AIDS, which has been classified a pandemic by the World Health Organization. It has been estimated that over 35 million people have died from this pandemic. Its origin is believed to have been first present in the 1920s but it did not become identified until 1981. Severe Acute Respiratory Syndrome (SARS) is considered among the most recent viral diseases that began in 2003. Although initially the global community was slow to contain it, eventually the impact of SARS became limited as containment and quarantine became effectively used. This pandemic is perhaps the least deadly, with less than 1000 deaths recorded.<ref>For more on recent pandemics, see: Honigsbaum, M., 2019. <i>The pandemic century: one hundred years of panic, hysteria, and hubris</i>, First edition. ed. W. W. Norton & Company, New York. </ref>