meaning of the epidemic

What is a pandemic? Why do health authorities around the world pay attention to following up, following up, studying, and trying to besiege new viruses from their inception?

Many contagious viral diseases appear, but their risk depends on the speed and extent of their spread in humans. Therefore, the concerned health authorities set definitions of the extent of infection and the seriousness of the spread.

The World Health Organization has developed a classification of the stages of the spread of infectious viruses to educate the public and define the meaning of the epidemic, so what is the meaning of each stage?

The first stage: viruses are in animals only, and no virus has been detected in humans, and the possibility of transmitting the virus to humans is weak.

The second stage: No virus has been discovered in humans yet, but viruses in animals can be transmitted to humans.

The third stage: the emergence of infection in humans, but the virus has not yet been able to transmit from one person to another except in very rare cases.

The fourth stage: transmission of the virus from one person to another, but in a few and limited human groups, as the virus has not yet adapted to cause infection in humans.

Fifth stage: transmission of infection to large groups of people, but the virus is still confined to certain groups and areas, and this means that the virus has begun to adapt to cause infection in humans, but it has not yet developed to cause rapid, widespread infection.

The sixth stage (the epidemic stage "the current stage of Covid-19"): The infection spreads in an epidemic manner, and its transmission to humans is rapid and epidemiological.

Why do health authorities around the world pay attention to following up, following up, studying, and trying to besiege new viruses from their inception?

The fear always remains that any emerging virus will be able to quickly infect a person and move from person to person quickly, as happens these days with the Corona virus, which may lead to the spread of a general (pandemic) epidemic.

And because this virus is genetically new to humans, the human immunity against it is very weak or non-existent, so the probability of a general epidemic is higher, as happened with the emerging corona virus.

The general epidemic is the spread of the virus worldwide and occurs when a new virus appears that the human body has not previously been exposed to and there is no immunity to it yet. In the twentieth century, there were three general epidemics for one of the respiratory viruses, namely the influenza virus, which caused many infections and deaths:

1919-1918: It was known with the Spanish flu (it is believed that it began in China), and it was type A (H1N1). More than five hundred thousand people died in the epidemic in the United States and 20-50 million people died worldwide. Deaths reached 100 million, and it was estimated that about half of the dead were healthy young adults.

1958-1957: It was known as the Asian influenza A (H2N2) type, and the infection occurred in its beginning in China and caused the death of seventy thousand people in the United States.

1969-1968: It was known as Hong Kong flu and it was type A (H3N2), and the epidemic resulted in the death of thirty-four people in the United States.

Preparation: Prof. Dr. Ahmed Salem Bahamam