Portal: Pandemias

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El portal de pandemias y epidemias

Una pandemia ( / pænˈdɛmɪk / pan - DEM-ik ) es una epidemia de una enfermedad infecciosa que presenta un aumento repentino de casos y se propaga por una región extensa, por ejemplo, varios continentes o el mundo entero, afectando a un número considerable de personas. Las enfermedades endémicas generalizadas con un número estable de individuos infectados, como las recurrencias de la gripe estacional , generalmente se excluyen, ya que ocurren simultáneamente en grandes regiones del mundo en lugar de propagarse por todo el mundo.

A lo largo de la historia de la humanidad , ha habido varias pandemias de enfermedades como la viruela . La Peste Negra , causada por la Peste , causó la muerte de hasta la mitad de la población de Europa en el siglo XIV. El término pandemia no se había utilizado entonces, pero se utilizó para epidemias posteriores, incluida la pandemia de influenza A H1N1 de 1918 , más comúnmente conocida como gripe española , que es la pandemia más mortal de la historia . Las pandemias más recientes incluyen la pandemia de VIH/SIDA , la pandemia de gripe porcina de 2009 y la pandemia de COVID-19 . Casi todas estas enfermedades todavía circulan entre los humanos, aunque su impacto ahora es a menudo mucho menor.

En respuesta a la pandemia de COVID-19, 194 estados miembros de la Organización Mundial de la Salud iniciaron negociaciones sobre un Tratado Internacional sobre Prevención, Preparación y Respuesta ante Pandemias , con el requisito de presentar un borrador de este tratado a la 77.ª Asamblea Mundial de la Salud durante su convención de 2024. Además, el 6 de mayo de 2024, la Casa Blanca publicó una política oficial para gestionar de forma más segura los proyectos de investigación médica que involucran patógenos potencialmente peligrosos , incluidos virus y bacterias , que pueden representar un riesgo de pandemia. ( Artículo completo... )

Una epidemia (del griego ἐπί epi "sobre o por encima" y δῆμος demos "pueblo") es la propagación rápida de una enfermedad a un gran número de huéspedes en una población determinada en un corto período de tiempo. Por ejemplo, en las infecciones meningocócicas , una tasa de ataque superior a 15 casos por cada 100.000 personas durante dos semanas consecutivas se considera una epidemia.

Las epidemias de enfermedades infecciosas suelen ser causadas por varios factores, entre ellos un cambio en la ecología de la población huésped (por ejemplo, aumento del estrés o aumento de la densidad de una especie vectora), un cambio genético en el reservorio del patógeno o la introducción de un patógeno emergente en una población huésped (por movimiento del patógeno o del huésped). En general, una epidemia se produce cuando la inmunidad del huésped a un patógeno establecido o a un nuevo patógeno emergente se reduce repentinamente por debajo de la que se encuentra en el equilibrio endémico y se supera el umbral de transmisión.

Una epidemia puede limitarse a un lugar; sin embargo, si se propaga a otros países o continentes y afecta a un número considerable de personas, puede denominarse pandemia . La declaración de una epidemia suele requerir un buen conocimiento de una tasa de incidencia de referencia ; las epidemias de ciertas enfermedades, como la gripe , se definen como aquellas que alcanzan un aumento definido en la incidencia por encima de esta tasa de referencia. Algunos casos de una enfermedad muy rara pueden clasificarse como epidemia, mientras que muchos casos de una enfermedad común (como el resfriado común ) no lo serían. Una epidemia puede causar enormes daños en forma de pérdidas financieras y económicas, además de deterioro de la salud y pérdida de vidas. ( Artículo completo... )

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Imagen 1
Un médico de la peste y su vestimenta típica durante el siglo XVII.

La segunda pandemia de peste fue una serie importante de epidemias de peste que comenzaron con la Peste Negra , que llegó a la Europa medieval en 1346 y mató hasta la mitad de la población de Eurasia en los siguientes cuatro años. Siguió a la primera pandemia de peste que comenzó en el siglo VI con la Peste de Justiniano , pero que había terminado en el siglo VIII. Aunque la peste se extinguió en la mayoría de los lugares después de 1353, se volvió endémica y reapareció regularmente. Una serie de epidemias importantes ocurrieron a fines del siglo XVII, y la enfermedad reapareció en algunos lugares hasta fines del siglo XVIII o principios del siglo XIX. Después de esto, una nueva cepa de la bacteria dio lugar a la tercera pandemia de peste , que comenzó en Asia alrededor de mediados del siglo XIX.

La peste es causada por la bacteria Yersinia pestis , que existe en pulgas parásitas de varias especies en la naturaleza y de ratas en la sociedad humana. En caso de un brote, puede matar a todos sus huéspedes inmediatos y así extinguirse, pero puede permanecer activo en otros huéspedes a los que no mata, causando así un nuevo brote años o décadas después. ( Artículo completo... )
Imagen 2

La pintura de Pavel Fedotov muestra una muerte por cólera a mediados del siglo XIX.

The third cholera pandemic (1846–1860) was the third major outbreak of cholera originating in India in the 19th century that reached far beyond its borders, which researchers at University of California, Los Angeles (UCLA) believe may have started as early as 1837 and lasted until 1863. In the Russian Empire, more than one million people died of cholera. In 1853–1854, the epidemic in London claimed over 10,000 lives, and there were 23,000 deaths for all of Great Britain. This pandemic was considered to have the highest fatalities of the 19th-century epidemics.

It had high fatalities among populations in Asia, Europe, Africa and North America. In 1854, which was considered the worst year, 23,000 people died in Great Britain. (Full article...)
Image 3

Rash caused by epidemic typhus

Epidemic typhus, also known as louse-borne typhus, is a form of typhus so named because the disease often causes epidemics following wars and natural disasters where civil life is disrupted. Epidemic typhus is spread to people through contact with infected body lice, in contrast to endemic typhus which is usually transmitted by fleas.

Though typhus has been responsible for millions of deaths throughout history, it is still considered a rare disease that occurs mainly in populations that suffer unhygienic extreme overcrowding. Typhus is most rare in industrialized countries. It occurs primarily in the colder, mountainous regions of central and east Africa, as well as Central and South America. The causative organism is Rickettsia prowazekii, transmitted by the human body louse (Pediculus humanus corporis). Untreated typhus cases have a fatality rate of approximately 40%. (Full article...)
Image 4

A child with smallpox in Bangladesh in 1973. The bumps filled with thick fluid and a depression or dimple in the center are characteristic.

Smallpox was an infectious disease caused by variola virus (often called smallpox virus), which belongs to the genus Orthopoxvirus. The last naturally occurring case was diagnosed in October 1977, and the World Health Organization (WHO) certified the global eradication of the disease in 1980, making smallpox the only human disease to have been eradicated to date.

The initial symptoms of the disease included fever and vomiting. This was followed by formation of ulcers in the mouth and a skin rash. Over a number of days, the skin rash turned into the characteristic fluid-filled blisters with a dent in the center. The bumps then scabbed over and fell off, leaving scars. The disease was transmitted from one person to another primarily through prolonged face-to-face contact with an infected person or (rarely) via contaminated objects. Prevention was achieved mainly through the smallpox vaccine. Once the disease had developed, certain antiviral medications could potentially have helped, but such medications did not become available until after the disease was eradicated. The risk of death was about 30%, with higher rates among babies. Often, those who survived had extensive scarring of their skin, and some were left blind. (Full article...)
Image 5

"Chrysotis chloronota" (Festive Amazon). Catalogue of the Birds in the British Museum, Vol. 20 (1891).

The 1929–1930 psittacosis pandemic, also known as the psittacosis outbreak of 1929–1930 and the great parrot fever pandemic, was a series of simultaneous outbreaks of psittacosis (parrot fever) which, accelerated by the breeding and transportation of birds in crowded containers for the purpose of trade, was initially seen to have its origin in parrots from South America. It was shortly found to have spread from several species of birds from several countries worldwide to humans between mid 1929 and early 1930. Diagnosed by its clinical features and link to birds, it affected around 750 to 800 people globally, with a mortality of 15%. Its mode of transmission to humans by mouth-to-beak contact or inhaling dried bird secretions and droppings was not known at the time. The cause, Chlamydia psittaci, which usually remains dormant in birds until activated by stress of capture and confinement, was discovered after the pandemic.

Cases of psittacosis were reported in mid 1929, in Birmingham, United Kingdom, and linked to parrots from Buenos Aires, Argentina, where an ongoing outbreak of the disease had led to cautioning bird owners to declare their sick parrots. The origin of the outbreak in the Argentine city of Córdoba was traced to an import of 5,000 parrots from Brazil. Although the Argentine parrot trade was stopped, a number of birds were illegally sold on to visitors at its seaports, with the consequence that psittacosis was transmitted to several countries. (Full article...)
Image 6

Painting by Domenico Gargiulo, made during the first year of the outbreak

The Naples Plague was an epidemic of plague in the Kingdom of Naples, lasting from 1656 to 1658. The epidemic affected mostly Central Italy and Southern Italy, killing up to 1,250,000 people throughout the Kingdom of Naples according to some estimates.

In the city of Naples alone, approximately 150,000–200,000 people died in 1656 due to the plague, accounting for more than half of the population. The epidemic had a severe impact on the economic and social structure of Naples and some other affected areas. (Full article...)
Image 7
Colored Scanning electron microscope (SEM) image of SARS-CoV-2, speculated in 2020 as being the first virus to create Disease X

Disease X is a placeholder name that was adopted by the World Health Organization (WHO) in February 2018 on their shortlist of blueprint priority diseases to represent a hypothetical, unknown pathogen that could cause a future epidemic. The WHO adopted the placeholder name to ensure that their planning was sufficiently flexible to adapt to an unknown pathogen (e.g., broader vaccines and manufacturing facilities). Director of the US National Institute of Allergy and Infectious Diseases Anthony Fauci stated that the concept of Disease X would encourage WHO projects to focus their research efforts on entire classes of viruses (e.g., flaviviruses), instead of just individual strains (e.g., zika virus), thus improving WHO capability to respond to unforeseen strains. In 2020, experts, including some of the WHO's own expert advisors, speculated that COVID-19, caused by the SARS-CoV-2 virus strain, met the requirements to be the first Disease X. (Full article...)
Image 8

Smallpox vaccine and equipment for administering it

A vaccine is a biological preparation that provides active acquired immunity to a particular infectious or malignant disease. The safety and effectiveness of vaccines has been widely studied and verified. A vaccine typically contains an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins. The agent stimulates the body's immune system to recognize the agent as a threat, destroy it, and recognize further and destroy any of the microorganisms associated with that agent that it may encounter in the future.

Vaccines can be prophylactic (to prevent or alleviate the effects of a future infection by a natural or "wild" pathogen), or therapeutic (to fight a disease that has already occurred, such as cancer). Some vaccines offer full sterilizing immunity, in which infection is prevented. (Full article...)
Image 9
The Hong Kong flu, also known as the 1968 flu pandemic, was a flu pandemic that occurred in 1968 and 1969 and which killed between one and four million people globally. It is among the deadliest pandemics in history, and was caused by an H3N2 strain of the influenza A virus. The virus was descended from H2N2 (which caused the Asian flu pandemic in 1957–1958) through antigenic shift, a genetic process in which genes from multiple subtypes are reassorted to form a new virus. (Full article...)
Image 10

Soldiers sick with Spanish flu at a hospital ward at Camp Funston in Fort Riley, Kansas

The 1918–1920 flu pandemic, also known as the Great Influenza epidemic or by the common misnomer Spanish flu, was an exceptionally deadly global influenza pandemic caused by the H1N1 subtype of the influenza A virus. The earliest documented case was March 1918 in the state of Kansas in the United States, with further cases recorded in France, Germany and the United Kingdom in April. Two years later, nearly a third of the global population, or an estimated 500 million people, had been infected in four successive waves. Estimates of deaths range from 17 million to 50 million, and possibly as high as 100 million, making it one of the deadliest pandemics in history.

The pandemic broke out near the end of World War I, when wartime censors in the belligerent countries suppressed bad news to maintain morale, but newspapers freely reported the outbreak in neutral Spain, creating a false impression of Spain as the epicenter and leading to the "Spanish flu" misnomer. Limited historical epidemiological data make the pandemic's geographic origin indeterminate, with competing hypotheses on the initial spread. (Full article...)
Image 11

A world map illustrating the proportion of population infected with HIV in 2019

The global pandemic of HIV/AIDS (human immunodeficiency virus infection and acquired immunodeficiency syndrome) began in 1981, and is an ongoing worldwide public health issue. According to the World Health Organization (WHO), by 2023, HIV/AIDS had killed approximately 40.4 million people, and approximately 39 million people were infected with HIV globally. Of these, 29.8 million people (75%) are receiving antiretroviral treatment. There were about 630,000 deaths from HIV/AIDS in 2022. The 2015 Global Burden of Disease Study estimated that the global incidence of HIV infection peaked in 1997 at 3.3 million per year. Global incidence fell rapidly from 1997 to 2005, to about 2.6 million per year. Incidence of HIV has continued to fall, decreasing by 23% from 2010 to 2020, with progress dominated by decreases in Eastern Africa and Southern Africa. As of 2023, there are about 1.3 million new infections of HIV per year globally.

According to the WHO, the prevalence of HIV in the Africa Region was estimated at 1.1 million people as of 2018. The African Region accounts for two thirds of the incidence of HIV around the world. Sub-Saharan Africa is the region most affected by HIV. As of 2020, more than two thirds of those living with HIV are living in Africa. HIV rates have been decreasing in the region: From 2010 to 2020, new infections in eastern and southern Africa fell by 38%. Still, South Africa has the largest population of people with HIV of any country in the world, at 8.45 million, 13.9% of the population as of 2022. (Full article...)
Image 12

Medical professionals treating a COVID-19 patient in critical condition in an intensive care unit in São Paulo in May 2020

The COVID-19 pandemic (also known as the coronavirus pandemic and COVID pandemic), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began with an outbreak of COVID-19 in Wuhan, China, in December 2019. It spread to other areas of Asia, and then worldwide in early 2020. The World Health Organization (WHO) declared the outbreak a public health emergency of international concern (PHEIC) on 30 January 2020, and assessed the outbreak as having become a pandemic on 11 March.

COVID-19 symptoms range from asymptomatic to deadly, but most commonly include fever, sore throat, nocturnal cough, and fatigue. Transmission of the virus is often through airborne particles. Mutations have produced many strains (variants) with varying degrees of infectivity and virulence. COVID-19 vaccines were developed rapidly and deployed to the general public beginning in December 2020, made available through government and international programs such as COVAX, aiming to provide vaccine equity. Treatments include novel antiviral drugs and symptom control. Common mitigation measures during the public health emergency included travel restrictions, lockdowns, business restrictions and closures, workplace hazard controls, mask mandates, quarantines, testing systems, and contact tracing of the infected. (Full article...)
Image 13

The angel of death striking a door during the plague of Rome: an engraving by Levasseur after Jules-Elie Delaunay

The Antonine Plague of AD 165 to 180, also known as the Plague of Galen (after Galen, the Greek physician who described it), was a prolonged and destructive epidemic, which impacted the Roman Empire. It was possibly contracted and spread by soldiers who were returning from campaign in the Near East. Scholars generally believe the plague was smallpox,due to the skin eruptions over the entirety of the body which appeared to be red and black (Horgan), although measles has also been suggested, and recent genetic evidence strongly suggests that the most severe form of smallpox only arose in Europe much later. As yet, there is no genetic evidence from the Antonine plague.

In AD 169 the plague may have claimed the life of the Roman emperor Lucius Verus, who was co-regnant with Marcus Aurelius. These two emperors had risen to the throne by virtue of being adopted by the previous emperor, Antoninus Pius, and as a result, their family name, Antoninus, has become associated with the pandemic. (Full article...)
Image 14
The Persian plague epidemic of 1772–1773, also simply known as the Persian Plague, was a massive outbreak of plague, more specifically Bubonic plague, in the Persian Empire, which claimed around 2 million lives in total. It was one of the most devastating Plague epidemics in recorded human history. The outbreak resulted in the introduction of several quarantine measures for the first time in the Persian Gulf regions. (Full article...)
Image 15
Crimson Contagion was a joint exercise conducted from January to August 2019, in which numerous national, state and local, private and public organizations in the US participated, in order to test the capacity of the federal government and twelve states to respond to a severe pandemic of influenza originating in China.

The simulation, which was conducted by the Department of Health and Human Services in a series of exercises that ran from January to August 2019, involved a scenario in which a group of about 30 tourists returning from China spread a novel influenza A respiratory virus in the United States, beginning in Chicago. In less than two months the virus had spread from a single index case (a 52-year-old man returning to Chicago) to infect 110 million Americans; 7.7 million patients would require hospitalization, and 586,000 people would die from the novel virus. The 70-page report issued at the conclusion of the exercise outlined the government's limited capacity to respond to a pandemic. States experienced "multiple challenges" requesting resources from the federal government "due to a lack of standardized, well-understood, and properly executed resource request processes," the report said. Federal agencies lacked the funds, coordination, and capacities to implement an effective response to the virus. (Full article...)

Imágenes generales -cargar nuevo lote

Las siguientes son imágenes de varios artículos relacionados con pandemias y epidemias en Wikipedia.

Image 1Eliminación de cadáveres durante la epidemia de cólera en Palermo en 1835 (de Historia del cólera )
Image 2Cadáveres de refugiados ruandeses que murieron durante la epidemia de cólera, octubre de 1994 (de Historia del cólera )
Image 3Los distintos tipos de virus de la gripe en los seres humanos. Los cuadrados sólidos muestran la aparición de una nueva cepa, que provoca pandemias de gripe recurrentes. Las líneas discontinuas indican identificaciones de cepas inciertas. (de Pandemia de gripe )
Image 4La plaga de Atenas ( c. 1652-1654 ) de Michiel Sweerts , que ilustra la devastadora epidemia que azotó Atenas en el año 430 a. C. , tal como la describe el historiador Tucídides (de Epidemia )
Image 5Ejemplos a escala de pandemias de gripe pasadas y temporadas de gripe pasadas. Se incluye un esquema de colores para representar las estimaciones correspondientes de muertes por gripe hipotéticas en la población estadounidense de 2010, con la misma escala de colores que la figura anterior. (del Marco de evaluación de la gravedad de la pandemia )
Image 6Ejemplo de una epidemia que muestra el número de nuevas infecciones a lo largo del tiempo. (de Epidemia )
Image 7Diferencia entre las distribuciones por edad de la mortalidad por influenza de la epidemia de 1918 y las epidemias normales. Muertes por cada 100.000 personas en cada grupo de edad, Estados Unidos, para los años interpandémicos de 1911 a 1917 (línea discontinua) y el año pandémico de 1918 (línea continua). (de Influenza pandémica )
Image 8Pabellón de gripe del Hospital Walter Reed , en Washington, DC, durante la pandemia de gripe de 1918 (de Pandemia de gripe )
Image 9El 12 de febrero de 2009, el número de casos de infección por cólera en el África subsahariana había llegado a 128.548 y el número de víctimas mortales, a 4.053. (de Historia del cólera )
Image 10Intervalos de influenza en el Marco de Intervalos Pandémicos de los CDC (de Influenza pandemia )
Image 11Registro de pacientes del Hospital Naval de Gosport, casos de cólera de agosto de 1832 (de Historia del cólera )
Image 12Una bomba en memoria de John Snow por su estudio del agua contaminada como una posible fuente de cólera durante el brote de cólera de Broad Street de 1854 (de Historia del cólera )
Image 13Pacientes afectados de cólera en 1854 (de Historia del cólera )
Image 14Un tribunal para el rey Cólera. Ilustración de Punch (1852). (de Epidemic )
Image 15Estructura del virus de la gripe. Las proteínas hemaglutinina (HA) y neuraminidasa (NA) se muestran en la superficie de la partícula. Los ARN virales que forman el genoma se muestran como espirales rojas dentro de la partícula y unidos a proteínas ribonucleares (RNP). (de Influenza pandémica )
Image 16Mosquito Anopheles, vector de la malaria (de Epidemic )
Image 17Primera pandemia de cólera (de Historia del cólera )
Image 18Brote de cólera en Hamburgo en 1892 , sala de hospital (de Historia del cólera )
Image 19Posibilidades de transmisión de enfermedades zoonóticas (de Epidemia )
Image 20Estimaciones de muertes hipotéticas por influenza en la población de los Estados Unidos en 2010 (308.745.538 personas) a través de diferentes valores de la tasa de letalidad y la incidencia acumulada de infección en la población. Las cifras estimadas de muertes seleccionadas se indican con una línea negra, a lo largo de cada combinación relevante de tasa de letalidad e incidencia acumulada. Además, el color de fondo pasa de azul a amarillo y luego a rojo a medida que aumenta la cantidad absoluta estimada de muertes. La tasa de letalidad es un ejemplo de una medida de gravedad clínica y la incidencia acumulada de infección es un ejemplo de una medida de transmisibilidad en el Marco de evaluación de la gravedad de la pandemia. (del Marco de evaluación de la gravedad de la pandemia )
Image 21Factura de la Junta de Salud de la Ciudad de Nueva York , 1832. Los consejos de salud pública obsoletos demuestran la falta de comprensión de la enfermedad y sus factores causales reales. (de Historia del cólera )