A pandemic (/pænˈdɛmɪk/pan-DEM-ik) is an epidemic of an infectious disease that has spread across a large region, for instance multiple continents or worldwide, affecting a substantial number of individuals. Widespread endemic diseases with a stable number of infected individuals such as recurrences of seasonal influenza are generally excluded as they occur simultaneously in large regions of the globe rather than being spread worldwide.
recognition of increased potential for ongoing transmission,
initiation of a pandemic wave,
acceleration of a pandemic wave,
deceleration of a pandemic wave, and
preparation for future pandemic waves.
(430 to 426 BC): During the Peloponnesian War, an epidemic killed a quarter of the Athenian troops and a quarter of the population. This disease fatally weakened the dominance of Athens, but the sheer virulence of the disease prevented its wider spread; i.e., it killed off its hosts at a rate faster than they could spread it. The exact cause of the plague was unknown for many years. In January 2006, researchers from the University of Athens analyzed teeth recovered from a mass grave underneath the city and confirmed the presence of bacteria responsible for typhoid fever.[71]
Plague of Athens
(165 to 180 AD): Possibly measles or smallpox brought to the Italian peninsula by soldiers returning from the Near East, it killed a quarter of those infected, up to five million in total.[72]
Antonine Plague
(251–266 AD): A second outbreak of what may have been the same disease as the Antonine Plague killed (it was said) 5,000 people a day in Rome.[73]
Plague of Cyprian
(541 to 549 AD): Also known as the First Plague Pandemic. This epidemic started in Egypt and reached Constantinople the following spring, killing (according to the Byzantine chronicler Procopius) 10,000 a day at its height, and perhaps 40% of the city's inhabitants. The plague went on to eliminate a quarter to half the human population of the known world and was identified in 2013 as being caused by bubonic plague.[74][75]
Plague of Justinian
(1331 to 1353): Also known as the Second Plague Pandemic. The total number of deaths worldwide is estimated at 75 to 200 million. Starting in Asia, the disease reached the Mediterranean and western Europe in 1348 (possibly from Italian merchants fleeing fighting in Crimea) and killed an estimated 20 to 30 million Europeans in six years;[76] a third of the total population,[77] and up to a half in the worst-affected urban areas.[78] It was the first of a cycle of European plague epidemics that continued until the 18th century;[79] there were more than 100 plague epidemics in Europe during this period,[80] including the Great Plague of London of 1665–66 which killed approximately 100,000 people, 20% of London's population.[81]
Black Death
. Previously endemic in the Indian subcontinent, the pandemic began in Bengal, then spread across India by 1820. The deaths of 10,000 British troops were documented - it is assumed that tens of thousands of Indians must have died.[82] The disease spread as far as China, Indonesia (where more than 100,000 people succumbed on the island of Java alone)[83] and the Caspian Sea before receding. Subsequent cholera pandemics during the 19th century are estimated to have caused many millions of deaths globally.[84][85]
(1855–1960): Starting in China, it is estimated to have caused over 12 million deaths in total, the majority of them in India.[86][87] During this pandemic, the United States saw its first outbreak: the San Francisco plague of 1900–1904.[88] The causative bacterium, Yersinia pestis, was identified in 1894.[89] The association with fleas, and in particular rat fleas in urban environments, led to effective control measures. The pandemic was considered to be over in 1959 when annual deaths due to plague dropped below 200. The disease is nevertheless present in the rat population worldwide and isolated human cases still occur.[90]
Third plague pandemic
The 1918–1920 infected half a billion people[91] around the world, including on remote Pacific islands and in the Arctic—killing 20 to 100 million.[91][92] Most influenza outbreaks disproportionately kill the very young and the very old, but the 1918 pandemic had an unusually high mortality rate for young adults.[93] It killed more people in 25 weeks than AIDS did in its first 25 years.[94][95] Mass troop movements and close quarters during World WarI caused it to spread and mutate faster, and the susceptibility of soldiers to the flu may have been increased by stress, malnourishment and chemical attacks.[96] Improved transportation systems made it easier for soldiers, sailors and civilian travelers to spread the disease.[97]
In 2016, the commission on a Global Health Risk Framework for the Future estimated that pandemic disease events would cost the global economy over $6 trillion in the 21st century—over $60 billion per year.[144] The same report recommended spending $4.5 billion annually on global prevention and response capabilities to reduce the threat posed by pandemic events, a figure that the World Bank Group raised to $13 billion in a 2019 report.[145] It has been suggested that such costs be paid from a tax on aviation rather than from, e.g., income taxes,[146] given the crucial role of air traffic in transforming local epidemics into pandemics (being the only factor considered in state-of-the-art models of long-range disease transmission [147]).
The COVID-19 pandemic is expected to have a profound negative effect on the global economy, potentially for years to come, with substantial drops in GDP accompanied by increases in unemployment noted around the world.[45] The slowdown of economic activity early in the COVID-19 pandemic had a profound effect on emissions of pollutants and greenhouse gases.[148][149][150] Analysis of ice cores taken from the Swiss Alps have revealed a reduction in atmospheric lead pollution over a four-year period corresponding to the years 1349 to 1353 (when the Black Death was ravaging Europe), indicating a reduction in mining and economic activity generally.[151]
