But in the fall of 1918 an unexpected virus occurred in North America and Europe. The cause was a subtype of avian influenza H1N1 from which humans died within a few hours to a few days. Within four months, Spanish fever, as she remained in the history of medicine as the most productive, has spread to the world and has reached even the most isolated societies.
By next spring, about 5 percent of the world's population had already died. A hundred years later, the 1918 pandemic seemed like something a long time ago and impossible as goddesses, plagues or other fatal diseases that we mostly wiped out. However, the grip never left us completely. He still dies between 250,000 and 500,000 people annually. Every year, there is a slightly changed load. Apart from 1918, pandemics occurred in 1957, 1968, 1977 and by 2009.
Experts agree that it's only time when a new type of virus will appear as infectious and lethal as the Spanish fever, and perhaps even worse than it.
"The influenza pandemic is similar to earthquakes, hurricanes or tsunami – it's never clear how strong it will be," says Michael Osterholm, Head of the Center for Research and Policies for Infectious Diseases at the University of Minnesota.
"The idea that it will not be repeated in 1918 is stupid," he says, although he agrees that this is impossible to predict, but at least it can be guessed.
"To begin with, the impact of the virus will depend on whether we have taken it early enough," said Robert Webster, expert. There are systems that can do this: The World Health Organization, has a fight against influenza virus and continuously monitors their development in six key laboratories around the world, as well as in farm laboratories that cause pigs and pigs.
"Surveillance is, of course, good, but we can not check every bird or any pig in the world," said Webster.
The reality is that the virus will be displayed safely.
"When this happens, it will go around the world and, in view of people's mobility, within a few weeks will come to different parts of the world," said Herardo Chauvel, Professor of Epidemiology and Biostatistics at the University of Georgia, adding:
"The infected person spreads the virus one day before he knows the first symptoms."
Since the number of people on the planet has more than tripled over the past hundred years, it is likely that this time there would be more deaths. If it killed 50 million people in 1918, it could now be more than 200,000,000 worldwide.
"In 2009, in Mexico, many people came to the hospital only after they became very, and it was just too late," he says. For many of these victims, this was an economic decision: going to a doctor means one day out of profit and without pay.
If the pandemic hits the United States, there would also be major differences if the infected person is insured or has no health insurance. Those without health insurance are likely to wait later to go to the hospital.
"Vaccine is the best way to stop a pandemic," says Lon Simonsen, an epidemiologist of communicable diseases from Denmark.
But first of all, it requires identification of the virus, the creation of a vaccine and its distribution around the world – a task that is easier said than done. Influenza vaccines are now produced faster than 50-60 years ago, but this process still requires a certain amount of time and lasts for months.
"In the world over the first six to nine months, only 1-2 percent of the population had access to vaccines, and the problem is that at best the vaccine still has only 60 percent efficiency," he said.
If a pandemic occurred in 1918, cities around the world were likely to collapse. Companies and schools would be shut down; public transport would not be transported it would shut down the electricity, and dead bodies would start accumulating on the streets. The supply of food and medicine would be interrupted.
Even after the virus was extinguished independently, the consequences would be long lasting. The virus from 1918 was "very terrible", says Simonsen, because 95% of those who killed him were not very young or very old but in force so a large number of workers disappeared and the flu has had major repercussions on the whole family because the children were without parents.
The researchers found out why it was in 2005 when researchers built the Spanish influenza virus from samples taken from Brevig's mission in Alaska. Of the 80 people 72 died in less than a week, but they managed to test the lungs from the lungs because the body of a victim was preserved in permafrost. They discovered that the 1918 type of influenza has increased well enough. Namely, the body killed itself because the virus initiated natural immunity and the so-called "cytokine storm", where the body exposes compounds that are intended to prevent virus attacks. Cytokines are somewhat toxic – they are responsible for the pains we feel when we have flu, and for Many can damage the organs and cause a breakdown of the immune system.
Because adults have a stronger immune system than children and elderly, scientists believe that their stronger response to the grip has proven to be fatal.
"We finally realized why the virus was so incredibly pathogenic. The body was most killed," said Webster.
In the coming decades, researchers have developed various therapies that can help relieve "cytokine storms". But these treatments are not completely perfect, and they are not widely available. The huge loss of young people and middle-aged people can endanger the world economy in this case. Nevertheless, there is a chance of salvation: universal influenza vaccine. Efforts to develop such a vaccine are gaining momentum, but they are still waiting. "Studies are ongoing, so we hope that such a hypothetical virus appears at the moment, this vaccine is already ready. For now we have not managed," said Webster.