WHO: What is a pandemic?

The world has experienced many pandemics, each passing pandemic has left heavy human and economic consequences. When does a disease become a pandemic?

World Health Organization - WHO defines a pandemic as follows: “A pandemic is the worldwide spread of a new disease”. An endemic disease that is widespread and stable in numbers is not a pandemic. Thus, for a disease to be called a pandemic, it must ensure two factors: it must be a new disease and it must spread widely around the world.
In May 2009, Dr. Keiji Fukuda, Interim Assistant Director-General for Health Security and Environment, WHO, told a virtual press conference on the flu pandemic that it was easy to think About the calendar it is: a pandemic is a global outbreak. Then you might wonder: what is a global outbreak? A global outbreak means we see both the spread of the agent and then we see the effects of the disease beyond the spread of viruses, bacteria.
However, we need to be careful how we think about diseases and pandemics, because we would be wrong to classify cancer as a pandemic, even though it causes many deaths. Because according to Dr. Dumar, a pandemic must also be contagious or contagious.
Thus a disease is not called a pandemic if it only spreads or kills many people. Therefore, although cancer is the cause of many deaths, it is not called a pandemic because it is not a contagious disease.
An influenza pandemic occurs when a new influenza virus emerges and spreads around the world and most people do not have immunity to the virus. Viruses that have caused pandemics in the past are mostly derived from animal influenza viruses, which then spread and caused disease in humans. Pandemic influenza usually excludes recurrent seasonal flu.
Throughout human history there have been a number of pandemics such as smallpox, tuberculosis. One of the most devastating pandemics was the Black Death, which caused the deaths of 75-200 million people in the 14th century. Some recent pandemics such as HIV, Spanish flu, H1N1 flu pandemic, ..
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According to a study in the Bulletin of the World Health Organization, an infectious disease that spreads around the world can lead to the deaths of 700,000 people and cause annual economic losses of 500 billion USD. This study applies a theoretical model to calculate expected deaths and economic losses in rare pandemic scenarios.
Thus, the impact of the pandemic on people's lives and the world's economy is not small. The damage from pandemic risks is comparable to the damage caused by climate change.
This makes us see the need for policies, national investment and international cooperation of countries to prepare and prevent the pandemic.

HIV originated in Africa and spread to the United States via Haiti between 1966 and 1972. HIV/AIDS is currently a pandemic with infection rates as high as 25% in southern and eastern Europe Fly. In 2006, the HIV prevalence rate among pregnant women in South Africa was 29.1%.
Education on safe sex practices and bacteremia prevention training have helped slow transmission in some African countries. However, infection rates are rising again in Asia and the Americas. It is forecast that the number of people dying from AIDS in Africa could reach 90-100 million people by 2025.

Since its prevalence in the 19th century, cholera has killed tens of millions of people:
First Cholera Pandemic (1817-1824) Second Cholera Pandemic (1826-1837) Third Cholera Pandemic (1846-1860) Fourth Cholera Pandemic (1863-75) Fifth Cholera Pandemic (1881-96) Sixth Cholera Pandemic (1899-1923) Seventh Cholera Pandemic (1961-1975)

Influenza was first described by Doctor Hippocrates in 412 BC.
The first influenza pandemic was recorded in 1580 and since then there has been an influenza pandemic every 10-30 years. Pandemic flu of 1889 - 1890: also known as Russian flu. The H3N8 and H2N2 subtypes of influenza A virus have been identified as possibly the cause of this epidemic. It has a very high attack and fatality rate, with an estimated 1 million deaths. Spanish Flu (1918-1919): This disease spread and became a global pandemic on all continents and eventually infected about a third of the world's population, or about 500 million people. It happened irregularly and ended quickly, completely disappearing within 18 months. The virus that causes the Spanish flu is also considered to be the cause of Lethargica encephalitis in children. Recently, this virus was reconstructed by scientists at the CDC still preserved by the Alaskan permafrost. The H1N1 influenza virus has a small but important structure similar to the Spanish flu. Asian flu (1957-1958): H2N2 virus was first identified in China in late February 1957. Hong Kong flu (1968-1969): an H3N2 influenza virus first detected in Hong Kong Kong in early 1968 and spread to the United States later that year. Influenza A virus H3N2 is still circulating to this day.

Typhus is sometimes called “camp fever” because of the pattern of outbreaks that flare up during times of conflict. It is also known as “gaol fever” and “train fever” because it spreads violently in cramped areas such as prisons and ships.

Smallpox is an infectious disease caused by the Variola virus. The disease killed about 400,000 Europeans a year by the end of the 18th century. After successful vaccination campaigns throughout the 19th and 20th centuries, in December 1979 the World Health Organization confirmed get rid of smallpox.
To this day, early season disease is the only infectious disease in humans that has been completely eliminated. And is one of two infectious viruses to be destroyed.

Historically, measles was a common disease worldwide, because it was very contagious. In the United States, up to 90% of people were infected with measles by the age of 15, before the measles vaccine was introduced in 1963.
The 2000 measles pandemic claimed the lives of approximately 777,000 people out of a total of 40 million cases. disease worldwide. Measles is an endemic disease, which means it has been and is continuously present in a community.

About a third of the world's population is currently infected with the bacterium Mycobacterium tuberculosis that causes tuberculosis. About 5-10% of these latent viral infections will progress to disease, which, if not treated promptly, will claim the lives of half of these patients. Every year, around 8 million people worldwide contract tuberculosis and 2 million die from the disease.
Until now, tuberculosis is still one of the important health problems in developing countries like Vietnam.

Leprosy, also known as Hansen's disease, is caused by the bacterium Mycobacterium leprae. It is a chronic disease with an incubation period of up to five years. Historically, leprosy has affected people since 600 BC. Countless leprosy hospitals were built during the medieval period.

Malaria is widespread in tropical and subtropical regions, including parts of the Americas, Asia and Africa. There are about 350-500 million cases of malaria each year. Resistance is occurring with the current classes of antimalarial drugs, with the exception of Artemisinin. Malaria was once common in most of Europe and North America, where the disease is now under control.

Yellow fever was the source of several devastating epidemics. Cities in the north such as New York, Philadelphia, Boston have been hit by this disease. In 1793 there was the largest outbreak of yellow fever in American history, causing about 5,000 deaths in Philadelphia. About half of the residents here have fled the city, including President George Washington.

Black Death is the name of an epidemic of bubonic plague that occurred in Asia and Europe in the 14th century, peaking in 1346-1351 with the death toll in Asia and Europe being about 75 - 200 million people . This is considered one of the deadliest pandemics in human history.
Plague is a disease caused by the bacterium Yersinia pestis and is spread by fleas that live on black rats. Once infected, the patient can only live about 60 - 180 hours. During the past 2000 years, the plague has caused three pandemics:
The first occurred in the 6th century. The second occurred in the XIV century. The third time in the nineteenth century, started in China and then spread to Asia, America. Article references source: Who.in, Sciencedaily.com