Pandemic

toc =What does pandemic mean?= A disease epidemic occurs when there are more cases of that disease than normal. A pandemic is a worldwide epidemic of a disease.

A pandemic is a disease that is infectious. An epidemic is a widespread occurrence of a disease (infectious and non-infectious). For example, cancer is an epidemic, since it is not contagious. An example of a pandemic would be HIV or AIDS. There are 6 phases before an infectious disease is identified as a pandemic. Prior to this identification, the disease would be identified as an epidemic. =How does a pandemic develop?= There are various ways that previous pandemics have developed. The Black (Black Plague) for example, developed from a pathogen (Yersinia pestis) which initially replicated within the midguts of fleas. The replication process of the pathogen created a blockage, which then resulted in starvation and aggressive feeding behaviour by the fleas “which repeatedly attempt to clear their blockage by regurgitation, resulting in thousands of plague bacteria being flushed into the feeding site, infecting the host. The bubonic plague mechanism was also dependent on two populations of rodents—one resistant to the disease, who act as hosts, keeping the disease endemic, and a second who lack resistance. When the second population die, the fleas move on to other hosts, including people, thus creating a human epidemic.”

Alternatively, the more recent ‘swine flu’ pandemic of 2009 was an outbreak of a new strain of H1N1 influenza virus (which was the virus that caused “the Spanish flu”). The new strain of H1N1 resulted when a triple reassortment of bird, swine and human flu viruses further combined with a Eurasian pig flu virus. These viruses generally just reside within the animal host (e.g. birds). Although, a major change within the virus can occur, which allows it to infect and be easily transmitted between humans. These major changes can occur one of two ways:
 * 1) Reassortment, which is the mixing of the genes from an animal or bird virus and a human influenza virus
 * 2) Adaptive mutation, which is change in the genes of an animal influenza virus, which allows it to infect humans

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The WHO has studied the development of previous pandemics in detail and stated that the next pandemic is likely to develop by moving through the following steps: The length of time it takes for a virus to develop from one which can only affect birds or animals, to one that can cause a human pandemic is unknown. In the past, when a pandemic virus has emerged, the virus has affected all continents over one to two years, often in waves lasting a few months at a time.
 * First, an influenza virus in birds or animals develops the ability to be able to infect humans and cause serious disease. During this initial phase, although the virus can cause disease in humans, the virus is unable to transmit efficiently between humans. Contact with infected animals is needed for human infection to occur.
 * Following further genetic change, the virus may become more efficient at passing from human to human, first within small groups or clusters (families or community networks) and later over wider but still localised areas.
 * Finally, the virus is able to transmit readily between humans. It spreads rapidly because of the short incubation period and the infectious nature of influenza. Rapid global spread is aided by the large amount of international travel that takes place every day between virtually every country in the world.

If an influenza pandemic were to occur today, we could expect the virus to spread rapidly due to the interconnected nature of the world and the high level of global travel.

=Examples of pandemics (timeline):=

Table

The Black Death
1348 – 1771 The Black Death

Approximately 150 million people died worldwide Killed 30%-60% of Europe’s population

In [|towns] and cities people lived very close together and they knew nothing about contagious diseases. Also the disposal of bodies was very crude and helped to spread the disease still further as those who handled the dead bodies did not protect themselves in any way. The filth that littered streets gave rats the perfect environment to breed and increase their number. It is commonly thought that it was the rats that caused the disease. This is not true – the fleas did this. However, it was the rats that enabled the disease to spread very quickly and the filth in the streets of our [|towns] and cities did not help to stop the spread of the disease. Lack of [|medical knowledge] meant that people tried anything to help them escape the disease. One of the more extreme was the flagellants. These people wanted to show their love of God by whipping themselves, hoping that God would forgive them their sins and that they would be spared the Black Death.

Malaria
1600 – Now Malaria

Kills about approximately 3 million people annually (one death every 30 seconds) Death rate could double in the next in the next 20 years

Cholera
1817 – Now Cholera

First: 1817-1823, Second: 1829-1851, Third: 1852-1859, Fourth: 1863-1879, Fifth: 1881-1896, Sixth: 1899-1923: Seventh: 1961- 1970, and some would argue that we are in the Eighth: 1991 to the present. Each pandemic, save the last, was accompanied by many thousands of deaths. As recently as 1947, 20,500 of 30,000 people infected in Egypt died. Despite modern medicine, cholera remains an efficient killer.

"The Spanish Flu" - Virus Type A (H1N1)
1918 – 1919 "Spanish" Virus Type A (H1N1)

Worldwide, 40-50 million people died (double the amount of Australia’s current population) 25% of the world’s population was affected Most of the people affected were young and healthy people aged 15-35 years Killed more people than Hitler, nuclear weapons and all there terrorists of history combined

After the lethal second wave struck in the autumn of 1918, new cases dropped abruptly — almost to nothing after the peak in the second wave. In Philadelphia for example, 4,597 people died in the week ending October 16, but by November 11 influenza had almost disappeared from the city. One explanation for the rapid decline of the lethality of the disease is that doctors simply got better at preventing and treating the pneumonia which developed after the victims had contracted the virus, although John Barry states in his book that researchers have found no evidence to support this. Another theory holds that the 1918 virus mutated extremely rapidly to a less lethal strain. This is a common occurrence with influenza viruses: there is a tendency for pathogenic viruses to become less lethal with time, providing more living hosts.

The Asian Flu - Virus Type A (H2N2)
1957 – 1958 "Asian" Virus Type A (H2N2)

High number of infected people, but the illness was relatively mild compared to the Spanish flu, which meant milder effects and fewer deaths First wave was amongst school children Caused 2 million deaths worldwide The virus arose from a genetic reassortment of a bird virus

The Hong Kong Flu - Virus Type A (H3N2)
1968 – 1970 "Hong Kong" Virus Type A (H3N2)

Affected the elderly Caused 1 million deaths worldwide

HIV and AIDS
1969 – Now HIV and AIDS (Acquired Immune Deficiency Syndrom)

AIDS death toll in Africa may reach 90-100 million by 2025

H1N1 influenza virus
2009 H1N1 influenza virus (derived from human, swine and avian strains)

37,636 cases of the pandemic 191 associated deaths

=Future pandemics=

Viral hemorrhagic fevers
Some Viral Hemorrhagic Fever causing agents like [|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]. Their ability to spread efficiently enough to cause a [|pandemic] is limited, however, as transmission of these [|viruses] requires close contact with the infected vector, and the vector only has a short time before death or serious illness. Furthermore, the short time between a vector becoming infectious and the onset of symptoms allows medical professionals to quickly quarantine vectors, and prevent them from carrying the pathogen elsewhere. Genetic mutations could occur, which could elevate their potential for causing widespread harm; thus close observation by contagious disease specialists is merited.

Antibiotic resistance
Antibiotic-resistant microorganisms, sometimes referred to as "superbugs", may contribute to the re-emergence of diseases which are currently well-controlled. For example, cases of [|tuberculosis] that are resistant to traditionally effective treatments remain a cause of great concern to health professionals. Every year, nearly half a million new cases of multidrug-resistant [|tuberculosis] (MDR-TB) are estimated to occur worldwide. After India, China has the highest rate of multidrug-resistant TB. The World Health Organization (WHO) reports that approximately 50 million people worldwide are infected with MDR TB, with 79 percent of those cases resistant to three or more antibiotics. In 2005, 124 cases of MDR TB were reported in the United States. Extensively drug-resistant [|tuberculosis] (XDR TB) was identified in Africa in 2006, and subsequently discovered to exist in 49 countries, including the United States. About 40,000 new cases of XDR-TB emerge every year, the WHO estimates.

The plague bacterium Yersinia pestis could develop drug-resistance and become a major health threat. Plague epidemics have occurred throughout human history, causing over 200 million deaths worldwide. The ability to resist many of the antibiotics used against plague has been found so far in only a single case of the disease in Madagascar. In the past 20 years, common bacteria including [|Staphylococcus aureus], Serratia marcescens and Enterococcus, have developed resistance to various antibiotics such as vancomycin, as well as whole classes of antibiotics, such as the aminoglycosides and cephalosporins. Antibiotic-resistant organisms have become an important cause of healthcare-associated (nosocomial) infections (HAI). In addition, infections caused by community-acquired strains of methicillin-resistant [|Staphylococcus aureus] (MRSA) in otherwise healthy individuals have become more frequent in recent years. Inappropriate antibiotic treatment and overuse of antibiotics have been an element in the emergence of resistant bacteria. The problem is further exacerbated by self-prescribing of antibiotics by individuals without the guidelines of a qualified clinician and the non-therapeutic use of antibiotics as growth promoters in agriculture

SARS
In 2003, there were concerns that Severe Acute Respiratory Syndrome (SARS), a new and highly contagious form of atypical [|pneumonia], might become [|pandemic]. It is caused by a coronavirus dubbed SARS-CoV. Rapid action by national and international health authorities such as the World Health Organization helped to slow transmission and eventually broke the chain of transmission. That ended the localized epidemics before they could become a [|pandemic]. However, the disease has not been eradicated. It could re-emerge. This warrants monitoring and reporting of suspicious cases of atypical [|pneumonia].

Influenza
Wild aquatic birds are the natural hosts for a range of [|influenza] A [|viruses]. Occasionally, [|viruses] are transmitted from these species to other species, and may then cause outbreaks in domestic poultry or, rarely, in humans.

H5N1 (Avian Flu)
In February 2004, avian [|influenza] [|virus] was detected in birds 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 bird 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 the United Kingdom. By November 2007, numerous confirmed cases of the [|H5N1] strain had been identified across Europe. However, by the end of October only 59 people had died as a result of [|H5N1] which was atypical of previous [|influenza pandemics].

Avian flu cannot yet be categorized as a "[|pandemic]", because the [|virus] cannot yet cause sustained and efficient human-to-human transmission. Cases so far are recognized to have been transmitted from bird to human, but as of December 2006 there have been very few (if any) cases of proven human-to-human transmission. Regular [|influenza] [|viruses] establish infection by attaching to receptors in the throat and lungs, but the avian [|influenza] [|virus] can only attach to receptors located deep in the lungs of humans, requiring close, prolonged contact with infected patients, and thus limiting person-to-person transmission.13

=Pandemic Biological Warfare= In 1346, the bodies of Mongol warriors who had died of plague were thrown over the walls of the besieged Crimean city of Kaffa (now Theodosia). After a protracted siege, during which the Mongol army under Jani Beg was suffering the disease, they catapulted the infected corpses over the city walls to infect the inhabitants. It has been speculated that this operation may have been responsible for the arrival of the Black Death in Europe.

The Native American population was devastated after contact with the Old World due to the introduction of many different fatal diseases. There is, however, only one documented case of germ warfare, involving British commander Jeffrey Amherst and Swiss-British officer Colonel Henry Bouquet, whose correspondence included a reference to the idea of giving [|smallpox]-infected blankets to Indians as part of an incident known as Pontiac's Rebellion which occurred during the Siege of Fort Pitt (1763) late in the French and Indian War. It is uncertain whether this documented British attempt successfully infected the Indians. During the Sino-Japanese War (1937–1945), Unit 731 of the Imperial Japanese Army conducted human experimentation on thousands, mostly Chinese. In military campaigns, the Japanese army used biological weapons on Chinese soldiers and civilians. Plague fleas, infected clothing, and infected supplies encased in bombs were dropped on various targets. The resulting [|cholera], anthrax, and plague were estimated to have killed around 400,000 Chinese civilians.

Diseases considered for weaponization, or known to be weaponized include anthrax, ebola, [|Marburg virus], plague, [|cholera], typhus, Rocky Mountain spotted fever, tularemia, brucellosis, Q fever, machupo, Coccidioides mycosis, Glanders, Melioidosis, Shigella, Psittacosis, Japanese B [|encephalitis], [|Rift Valley fever], [|yellow fever], and [|smallpox]. China possibly suffered a serious accident at one of its biological weapons plants in the late 1980s. The Soviets suspected that two separate epidemics of hemorrhagic fever that swept the region in the late 1980s were caused by an accident in a lab where Chinese scientists were weaponizing [|viral diseases]. In January 2009, an Al-Qaeda training camp in Algeria had been wiped out by the plague, killing approximately 40 Islamic extremists. Experts said that the group was developing biological weapons.

=Scenario of potential existential threat= Humanity’s existence can be

=How we deal with pandemics=

Pandemic Literature [|The Andromeda Strain] a 1969 [|science fiction] novel by [|Michael Crichton] [|Company of Liars] (2008), by [|Karen Maitland] [|The Decameron], a 14th century writing by Italian author [|Giovanni Boccaccio], circa 1353 [|Earth Abides], a 1949 novel by [|George R. Stewart] [|I Am Legend], a 1954 science fiction/horror novel by American writer [|Richard Matheson] [|The Last Canadian], a 1974 novel by [|William C. Heine] [|The Last Town on Earth], a 2006 novel by [|Thomas Mullen] [|Pale Horse, Pale Rider], a 1939 short novel by [|Katherine Anne Porter] [|The Stand], a 1978 novel by [|Stephen King] [|Two Journeys], a 2009 novel by [|Clemens P. Suter] The time-travel fiction of [|Connie Willis] (such as [|The Doomsday Book] and [|To Say Nothing of the Dog]) set in the mid-twenty-first century, frequently references a pandemic that occurred in the early part of the century.

Pandemic Films [|28 Days Later] (2002), a fictional horror film following the outbreak of an infectious 'rage' virus that destroys all of mainland Britain. [|28 Weeks Later] (2007), the sequel film to 28 Days Later, involving the NATO-led, United States Army supported repatriation of the British people, following the cessation of quarantine measures, and the complete erasure of infection surrounding mainland Britain. The film ends with the evident spread of 'rage' infection to Paris, and the remainder of mainland Europe. [|After Armageddon] (2010), fictional [|History Channel] [|docudrama] [|End Day] (2005), a fictional BBC docudrama [|The Horseman on the Roof] (Le Hussard sur le Toit), a 1995 French film [|The Last Man on Earth], a 1964 Italian horror/science fiction film based upon the [|Richard Matheson] novel [|I Am Legend]. The film was directed by [|Ubaldo Ragona] and [|Sidney Salkow], and stars [|Vincent Price]. [|The Omega Man], a 1971 English science fiction film directed by [|Boris Sagal], based on the [|Richard Matheson] novel I Am Legend [|Smallpox 2002] (2002), a fictional BBC docudrama [|I Am Legend], a 2007 film staring Will Smith based on the [|Richard Matheson] novel "I Am Legend" [|Twelve Monkeys] (1995), in a future world devastated by disease, a convict is sent back in time to gather information about the man-made virus that wiped out most of the human population on the planet.

(1) (2) (3) [] (4) [] (5) http://www.health.gov.au/internet/panflu/publishing.nsf/Content/how-develop-1 (6) [] (7) http://en.wikipedia.org/wiki/Black_Death#cite_note-0 (8) [] (9) [] (10) [] (11) http://en.wikipedia.org/wiki/1918_flu_pandemic#End_of_the_pandemic (12) [] (13) [] http://www.news-medical.net/health/Future-Pandemics.aspx