A pandemic is an epidemic over a wide geographic area and affecting a large proportion of the population: It is a global disease outbreak. An influenza pandemic occurs when a new influenza virus appears against which the human population has no immunity, resulting in several, simultaneous epidemics worldwide with enormous numbers of deaths and illness.
With the increase in global transport and communications, as well as urbanization and overcrowded conditions, epidemics due the new influenza virus are likely to quickly take hold around the world.
When a pandemic influenza virus emerges, its global spread is considered inevitable. Preparedness activities should assume that the entire world population would be susceptible. Countries might, through measures such as border closures and travel restrictions, delay arrival of the virus, but cannot stop it.
Most people have little or no immunity to a pandemic virus. Infection and illness rates soar. A substantial percentage of the world's population will require some form of medical care. Nations unlikely to have the staff, facilities, equipment and hospital beds needed to cope with large numbers of people who suddenly fall ill.
Death rates are high, largely determined by four factors: the number of people who become infected, the virulence of the virus, the underlying characteristics and vulnerability of affected populations and the effectiveness of preventive measures. Past pandemics have spread globally in two and sometimes three waves.
The need for vaccine is likely to outstrip supply. The need for antiviral drugs is also likely to be inadequate early in a pandemic. A pandemic can create a shortage of hospital beds, ventilators and other supplies. Surge capacity at non-traditional sites such as schools may be created to cope with demand Difficult decisions will need to be made regarding who gets antiviral drugs and vaccines.
Travel bans, closings of schools and businesses and cancellations of events could have major impact on communities and citizens. Care for sick family members and fear of exposure can result in significant worker absenteeism.Communications and information are critical components of pandemic response. Education and outreach are critical to preparing for a pandemic. Understanding what a pandemic is, what needs to be done at all levels to prepare for pandemic influenza, and what could happen during a pandemic helps us make informed decisions both as individuals and as a nation.
Source: Department of Health and Human Services
From Wikipedia, the free encyclopedia
A pandemic (from Greek pan all + demos people) is an epidemic (an outbreak of an infectious disease) that spreads worldwide, or at least across a large region.
Common killers and pandemics
According to the World Health Organization, a pandemic can start when three conditions have been met:
A disease or condition is not a pandemic merely because it is widespread or kills a large number of people; it must also be infectious. For example cancer is responsible for a large number of deaths but is not considered a pandemic because the disease is not infectious.
World Health Organization pandemic phases
The World Health Organization (W.H.O) has developed a global influenza preparedness plan, which defines the stages of a pandemic, outlines the role of W.H.O, and makes recommendations for national measures before and during a pandemic. The phases are:
Pandemic alert period:
Pandemics and notable epidemics through history
There have been a number of significant pandemics in human history, generally zoonoses that came about with domestication of animals - such as influenza and tuberculosis. There have been a number of particularly significant epidemics that deserve mention above the "mere" destruction of cities:
* Peloponnesian War, 430 BC. Typhoid fever 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. 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. 
* Antonine Plague, 165-180. Possibly smallpox brought 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 Egypt and reached Constantinople the 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 eliminate 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 plague returned 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.
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 Italy and lost supremacy in Italy to the Spanish. In 1542, 30,000 people died of typhus while fighting the Ottomans in 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 camps during World War II.
Effects of Colonization. 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 Islands in the 16th century. Half the native population of Hispaniola in 1518 was killed by smallpox. Smallpox also ravaged Mexico in the 1520s, killing 150,000 in Tenochtitlán alone, including the emperor, and Peru in the 1530s, aiding the European conquerors. Measles killed a further two million Mexican natives in the 1600s. As late as 1848-49, as many as 40,000 out of 150,000 Hawaiians are estimated to have died of measles, whooping cough and influenza.
There are also a number of unknown diseases that were extremely serious but have now vanished, so the etiology of these diseases cannot be established. The cause of English Sweat in 16th-century England, which struck people down in an instant and was more greatly feared even than the bubonic plague, is still unknown.
Concern about possible future pandemics
Ebola virus and other quickly lethal diseases
Lassa fever, Rift Valley fever, Marburg virus, Ebola virus and Bolivian hemorrhagic fever are highly contagious and deadly diseases with the theoretical potential to become pandemics. However, genetic mutations could occur at any time which could elevate their potential for causing widespread harm, thus close observation by contagious disease specialists is merited.
Antibiotic-resistant superbugs may also revive diseases previously regarded as "conquered".
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, where it is spreading more slowly. This is because it is somewhat more controllable, with education, than H5N1 and SARS as it can only transfer in limited ways (sexual acts being the primary cause of spread).
In 2003, there were concerns that SARS, a new highly contagious form of pneumonia, might become pandemic. It has since been declared 'eradicated' by the WHO.
Main article: H5N1
In February 2004, avian influenza virus 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 such as the Asian Flu and the Hong Kong Flu.
From October 2004 to February 2005, some 3,700 test kits of the 1957 Asian Flu virus were accidentally spread around the world from a lab in the US.
In May 2005, scientists urgently call nations to prepare for a global influenza pandemic that 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 Romania, and then Greece. Possible cases of the virus have also been found in Croatia, Bulgaria and in the United Kingdom.. However, by the end of October only 67 people had died as a result of H5N1 which was atypical of previous influenza pandemics.
Despite popular newspaper reports, Avian flu cannot yet be categorised as a "pandemic" because the disease has not been considered to have mutated. It has gone from bird to human, and in recent news human to human, but this is not proven.Reference
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