Pandemic

This article is about large epidemics. For the video game developer, see Pandemic Studios.

A pandemic, or global epidemic, is an outbreak of an infectious diseasethat affects people over an extensive geographical area (from Greekpan all + demos people).

Common killers and pandemics

According to the World Health Organization, a pandemic can start when three conditions have been met:

• the emergence of a disease new to the population
• the agent infects humans, causing serious illness
• the agent spreads easily and sustainably among humans.

A disease or condition is not a pandemic specifically because it kills a large number of people. For example, the class of diseases known as canceris responsible for a large number of deaths. But the deaths and disabilities due to cancer are not considered a pandemic because the condition is not infectious (although certain infectious agents are known to increase cancer risk).

World Health Organization pandemic phases

The World Health Organization(WHO) has developed a global influenza preparedness plan, which defines the stages of a pandemic, outlines the role of WHO, and makes recommendations for national measures before and during a pandemic. The phases are:

Interpandemic period:

• Phase 1: No new influenza virus subtypes have been detected in humans.

• Phase 2: No new influenza virus subtypes have been detected in humans, but an animal variant threatens human disease.

Pandemic alert period

• Phase 3: Human infection(s) with a new subtype but no human-to-human spread.

• Phase 4: Small cluster(s) with limited localized human-to-human transmission

• Phase 5: Larger cluster(s) but human-to-human spread still localized.

Pandemic period:

• Phase 6: Pandemic: increased and sustained transmission in general population.

Pandemics through history

There have been a number of significant pandemics in human history, generally zoonosesthat came about with domesticationof animals - such as influenzaand tuberculosis. There have been a number of particularly significant epidemics that deserve mention above the 'mere' destruction of cities:

• Peloponnesian War, 430 BCE. An unknown agent killed a quarter of the Athenian troops and a quarter of the population over four years. 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.

• Antonine Plague, 165-180. Possibly smallpoxbrought back from the Near East; killed a quarter of those infected and up to five million in all. At the height of a second outbreak (251-266) 5,000 people a day were said to be dying in Rome.

• Plague of Justinian, started 541. The first recorded outbreak of the bubonic plague. It started in Egyptand reached Constantinoplethe following spring, killing (according to the Byzantine chronicler Procopius) 10,000 a day at its height and perhaps 40 percent of the city's inhabitants. It went on to destroy up to a quarter of the human population of the eastern Mediterranean.

• The Black Death, started 1300s. Eight hundred years after the last outbreak, the bubonic plaguereturned to Europe. Starting in Asia, the disease reached Mediterranean and western Europe in 1348 (possibly from Italian merchants fleeing fighting in the Crimea), and killed twenty million Europeans in six years, a quarter of the total population and up to a half in the worst-affected urban areas.

• Cholera
  • first pandemic 1816-1826. Previously restricted to the Indiansubcontinent, the pandemic began in Bengal, then spread across India by 1820. It extended as far as Chinaand the Caspian Seabefore receding.
  • The second pandemic (1829-1851) reached Europe, Londonin 1832, OntarioCanadaand New Yorkin the same year, and the Pacific coast of North America by 1834.
  • The third pandemic (1852-1860) mainly affected Russia, with over a million deaths.
  • The fourth pandemic (1863-1875) spread mostly in Europe and Africa.
  • The sixth pandemic (1899-1923) had little effect in Europe because of advances in public health, but Russia was badly affected again.
  • The seventh pandemic began in Indonesiain 1961, called El Torafter the strain, and reached Bangladeshin 1963, India in 1964, and the USSRin 1966.

• Influenza
  • The "Asiatic Flu", 1889-1890. Was first reported in May of 1889 in Bukhara, Russia. By October, it had reached Tomskand the Caucasus. It rapidly spread west and hit North America in December 1889, South America in February-April 1890, India in February-March 1890, and Australia in March-April 1890. It was purportedly caused by the H2N8 type of flu virus and had a very high attack and mortality rate.
  • The "Spanish flu", 1918-1919. First identified early March 1918 in US troops training at Camp Funstan, Kansas, by October 1918 it had spread to become a world-wide pandemic on all continents. Unusually deadly and virulent, it ended nearly as quickly as it began, vanishing completely within 18 months. In six months, 25 million were dead; some estimates put the total of those killed worldwide at over twice that number. An estimated 17 million died in India, 500,000 in the United States and 200,000 in the UK. The virus was recently reconstructed by scientists at the CDCstudying remains preserved by the Alaskan permafrost. They identified it as a type of H1N1virus.
  • The "Asian Flu", 1957-58. An H2N2 caused about 70,000 deaths in the United States. First identified in China in late February 1957, the Asian flu spread to the United States by June 1957.
  • The "Hong Kong Flu", 1968-69. An H3N2 caused about 34,000 deaths in the United States. This virus was first detected in Hong Kong in early 1968 and spread to the United States later that year. Influenza A (H3N2) viruses still circulate today.

The epidemic disease of wartime was typhus, sometimes called "camp fever" because of its pattern of flaring up in times of strife. (It is also known as "gaol fever" and "ship fever", for its habits of spreading wildly in cramped quarters, such as jails and ships.) Emerging during the Crusades, it had its first impact in Europe in 1489 in Spain. During fighting between the Christian Spaniards and the Muslims in Granada, the Spanish lost 3,000 to war casualties and 20,000 to typhus. In 1528 the French lost 18,000 troops in Italyand lost supremacy in Italy to the Spanish. In 1542, 30,000 people died of typhus while fighting the Ottomansin the Balkans. The disease also played a major role in the destruction of Napoleon's Grande Armée in Russia in 1812. Typhus also killed numerous prisoners in the Nazi concentration campsduring World War II.

Encounters between European explorers and populations in the rest of the world often introduced local epidemics of extraordinary virulence. Disease killed the entire native (Guanches) population of the Canary Islandsin the 16th century. Half the native population of Hispaniolain 1518 was killed by smallpox. Smallpox also ravaged Mexicoin the 1520s, killing 150,000 in Tenochtitlánalone, including the emperor, and Peruin the 1530s, aiding the European conquerors. Measleskilled a further two million Mexican natives in the 1600s. As late as 1848-49, as many as 40,000 out of 150,000 Hawaiiansare estimated to have died of measles, whooping coughand influenza.

There are also a number of unknown diseases that were extremely serious but have now vanished, so the etiologyof these diseases cannot be established. Examples include the previously mentioned plague in 430 BCEGreece and the English Sweat in 16th-century England, which struck people down in an instant and was more greatly feared even than the bubonic plague.

Concern about possible future pandemics

Diseases that may possibly attain pandemic proportions include Lassa fever, Rift Valley fever, Marburg virus, Ebola virusand Bolivian hemorrhagic fever. As of 2004, however, emergences of these diseases into the human population in recent years has shown their virulence is so high they have burned out in geographically confined areas. Thus their effect on humans is currently limited.

HIV– the virus that causes AIDS– can be considered a global pandemic but it is currently most extensive in southern and eastern Africa. It is restricted to a small proportion of the population in other countries, and is only spreading slowly in those countries. If there were to be a true destruction-of-life pandemic it would be likely to be similar to HIV, i.e. a constantly evolving disease.

Antibiotic-resistant superbugsmay also revive diseases previously regarded as 'conquered'.

In 2003, there were concerns that SARS, a new highly contagious form of pneumonia, might become pandemic.

There is also a historical record of Influenza pandemics of varying severity at 20-40 year intervals. In February 2004, avian influenzavirus was detected in pigs in Vietnam, increasing fears of the emergence of new variant strains. It is feared that if the avian influenza virus combines with a human influenza virus (in a pig or a human), the new subtype created could be both highly contagious and highly lethal in humans. Such a subtype could cause a global influenza pandemic, similar to the Spanish Flu, or the lower mortality pandemics the Asian Fluand the Hong Kong Flu.

From October 2004 to February 2005, some 3,700 test kits of the 1957 Asian Fluvirus were accidentally spread around the world from a lab in the US[1].

In November 2004 the director for the western region of the World Health Organizationsaid that an influenzapandemic was inevitable and called for urgent plans to combat the virus.

In May 2005, scientists urgently call nations to prepare for a global influenza pandemicthat could strike as much as 20% of the world's population.

In October 2005, cases of the Avian flu (the deadly strain H5N1) were identified in Turkey. EU Health Commissioner Markos Kyprianou said: "We have received now confirmation that the virus found in Turkey is an avian flu H5N1 virus. There is a direct relationship with viruses found in Russia, Mongolia and China." Cases of bird flu were also identified shortly thereafter in bordering Romania, and then Greece. Possible cases of the virus have also been found in Croatia, Bulgaria and in the United Kingdom.^[2]. However, by the end of October only 67 people had died as a result of H5N1 which was atypical of previous influenza pandemics.

See also

• Endemic
• Epidemic
• List of epidemics
• Influenza pandemic

External links

• WHO - Authoritative source of information about global health issues
• Past pandemics that ravaged Europe
• CDC: Influenza Pandemic Phases
• U.S. governments's pandemic flu and avian flu information site
• The Flu Wiki - to help local communities prepare for and perhaps cope with a possible influenza pandemic.

Reference

• Awake!(magazine), December 22, 2005.bg:????????

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It uses material from the http://en.wikipedia.org/wiki/Pandemic Wikipedia article Pandemic.