A pandemic (from Greek πᾶν, pan, "all" and δῆμος, demos, "local people" the 'crowd') 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 people. A widespread endemic disease with a stable number of infected people is not a pandemic. Widespread endemic diseases with a stable number of infected people such as recurrences of seasonal influenza are generally excluded as they occur simultaneously in large regions of the globe rather than being spread worldwide.
Throughout human history, there have been a number of pandemics of diseases such as smallpox. The most fatal pandemic in recorded history was the Black Death (also known as The Plague), which killed an estimated 75–200 million people in the 14th century.[2][3][4][5][6][7] The term was not used yet but was for later pandemics including the 1918 influenza pandemic (Spanish flu).[8][9][10]
Current pandemics include tuberculosis,[11] COVID-19 (SARS-CoV-2) and HIV/AIDS.[12]
https://en.wikipedia.org/wiki/Pandemic
| Phase 1 | Phase 2 | Phase 3 | Phase 4 | Phase 5 | Phase 6 | Post peak | Possible new wave | Post-pandemic |
|---|---|---|---|---|---|---|---|---|
| Uncertain probability of pandemic | Medium to high probability | High to certain probability | Pandemic in progress | — | — | — | ||
| Animal-to-animal infection only | Animal-to-human infection | Sporadic or clustered cases in humans | — | — | — | — | — | — |
| — | (Considered a human pandemic threat) | No sustained community-level outbreaks | Sustained community-level outbreaks | Sustained in two countries in one WHO region | Sustained in-country in another WHO region | Levels drop below the peak in most countries | Activity rising again in most countries | Levels return to ordinary seasonal levels |
● Phases 3-6: "Sustained" implies human-to-human transmission. | ||||||||
Major outbreaks in countries[edit]
| Country name | Total cases | Total deaths | Total recovered | Active cases | Deaths % (of total cases) | Recovered % (of total cases) | Main article | Ref. |
|---|---|---|---|---|---|---|---|---|
| USA | 34,377,592 | 616,440 | 28,641,439 | 5,119,713 | 2.11 | 97.89 | COVID-19 pandemic in the United States | [52] |
In human history, it is generally zoonoses such as influenza and tuberculosis which constitute most of the widespread outbreaks, resulting from the domestication of animals. There have been many particularly significant epidemics that deserve mention above the "mere" destruction of cities:
- Plague of Athens (430 to 426 BC): During the Peloponnesian War, typhoid fever 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.[63]
- Antonine Plague (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.[64]
- Plague of Cyprian (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.
- Plague of Justinian (541 to 750 AD): The first recorded outbreak of bubonic plague 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.[65][66] It caused Europe's population to drop by around 50% between 550 AD and 700 AD.[67]
- Black Death (1331 to 1353): The total number of deaths worldwide is estimated at 75 to 200 million. Eight hundred years after the last outbreak, the plague returned to Europe. 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;[68] a third of the total population,[69] and up to a half in the worst-affected urban areas.[70]It was the first of a cycle of European plague epidemics that continued until the 18th century.[71] There were more than 100 plague epidemics in Europe during this period.[72] The disease recurred in England every two to five years from 1361 to 1480.[73] By the 1370s, England's population was reduced by 50%.[74] The Great Plague of London of 1665–66 was the last major outbreak of the plague in England and killed approximately 100,000 people, 20% of London's population.[75]
- Third plague pandemic (1855): Starting in China, it spread into India, where 10 million people died.[76] During this pandemic, the United States saw its first outbreak: the San Francisco plague of 1900–1904.[77] Today, sporadic cases of plague still occur in the western United States.[78]
- The 1918-1920 Spanish flu infected half a billion people[79]—around the world, including on remote Pacific islandsand in the Arctic—killing 20 to 100 million.[79][80] 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.[81] It killed more people in 25 weeks than AIDS did in its first 25 years.[82][83] Mass troop movements and close quarters during World War I 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.[84] Improved transportation systems made it easier for soldiers, sailors and civilian travelers to spread the disease.[85]
Artemisinin (/ˌɑːtɪˈmiːsɪnɪn/) and its semisynthetic derivatives are a group of drugs used in the treatment of malaria due to Plasmodium falciparum.[1] It was discovered in 1972 by Tu Youyou, who shared the 2015 Nobel Prize in Physiology or Medicine for her discovery.[2] Artemisinin-based combination therapies (ACTs) are now standard treatment worldwide for P. falciparum malaria as well as malaria due to other species of Plasmodium.[3] Artemisinin is extracted from the plant Artemisia annua, sweet wormwood, a herb employed in Chinese traditional medicine. A precursor compound can be produced using a genetically-engineered yeast, which is much more efficient than using the plant.[4]
Artemisinin and its derivatives are all sesquiterpene lactones containing an unusual peroxide bridge. This endoperoxide 1,2,4-trioxane ring is responsible for their antimalarial properties. Few other natural compounds with such a peroxide bridge are known.[5]
Artemisinin and its derivatives have been used for the treatment of malarial and parasitic worm (helminth) infections. They have the advantage over other drugs in having an ability to kill faster and kill all the life cycle stages of the parasites.[6] But low bioavailability, poor pharmacokinetic properties and high cost of the drugs are major drawbacks of their use.[7] Use of the drug by itself as a monotherapy is explicitly discouraged by the World Health Organization,[8] as there have been signs that malarial parasites are developing resistance to the drug. Therapies that combine artemisinin or its derivatives with some other antimalarial drug are the preferred treatment for malaria.[9]
https://en.wikipedia.org/wiki/Artemisinin
Plasmodium falciparum is a unicellular protozoan parasite of humans, and the deadliest species of Plasmodium that causes malaria in humans.[2] The parasite is transmitted through the bite of a female Anopheles mosquito and causes the disease's most dangerous form, falciparum malaria. It is responsible for around 50% of all malaria cases.[3][4] P. falciparum is therefore regarded as the deadliest parasite in humans. It is also associated with the development of blood cancer (Burkitt's lymphoma) and is classified as Group 2A carcinogen.
The species originated from the malarial parasite Laverania found in gorillas, around 10,000 years ago.[5] Alphonse Laveran was the first to identify the parasite in 1880, and named it Oscillaria malariae. Ronald Ross discovered its transmission by mosquito in 1897. Giovanni Battista Grassi elucidated the complete transmission from a female anopheline mosquito to humans in 1898. In 1897, William H. Welch created the name Plasmodium falciparum, which ICZN formally adopted in 1954. P. falciparum assumes several different forms during its life cycle. The human-infective stage are sporozoites from the salivary gland of a mosquito. The sporozoites grow and multiply in the liver to become merozoites. These merozoites invade the erythrocytes (RBCs) to form trophozoites, schizonts and gametocytes, during which the symptoms of malaria are produced. In the mosquito, the gametocytes undergo sexual reproduction to a zygote, which turns into ookinete. Ookinete forms oocytes from which sporozoites are formed.
As of the World Health Organization World Malaria Report 2020, there were 229 million cases of malaria worldwide in 2019, resulting in an estimated 409,000 deaths. Nearly all malarial deaths are caused by P. falciparum, and 94% of such cases occur in Africa. Children under five years of age are most affected, accounting for 67% of the total deaths. In Sub-Saharan Africa, almost 100% of cases were due to P. falciparum, whereas in most other malarial countries, other, less virulent plasmodial species predominate.[6]
https://en.wikipedia.org/wiki/Plasmodium_falciparum
Antibiotic-resistant microorganisms, which sometimes are referred to as "superbugs", may contribute to the re-emergence of diseases that are currently well controlled.[183] 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.[184] China and India have the highest rate of multidrug-resistant TB.[185] 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. There are about 40,000 new cases of XDR-TB per year, the WHO estimates.[186]
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.
https://en.wikipedia.org/wiki/Pandemic
- List of epidemics
- Asian Flu of 1957
- Biological hazard
- Bushmeat
- Compartmental models in epidemiology
- COVID-19 pandemic
- Crowdmapping
- Disease X
- European Centre for Disease Prevention and Control (ECDC)
- Hong Kong Flu of 1968
- Immunization
- Mathematical modelling of infectious disease
- Medieval demography
- Mortality from infectious diseases
- Pandemic fatigue
- Pandemic severity index
- Public health emergency of international concern
- Super-spreader
- Syndemic
- Tropical disease
- Timeline of global health
- Twindemic
- Vaccination
- WHO pandemic phases
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