Pandemic & infectious diseases in human history

In the early 20th century, there were two major epidemics, 1913 smallpox and Spanish flu in 1919. Spanish flu entered Australia after the first post-World War soldiers returned from Europe. into the population. At the height of the flu, up to 36% of the population is infected, of which 1.4% are fatal. In Sydney, the government of New South Wales ordered the closure of public theaters, people had to wear masks on public transport and offices.

Schools and pubs are closed, even in churches, horse racing is not organized. After the Spanish flu epidemic, there were two major flu pandemics spreading around the world, including the 1957 and 1968 flu, but not as severe as the 1918 flu . This is a terrifying lesson about epidemiology that today experts and health agencies in many countries around the world are concerned that bird flu spreads through people and becomes a contagious flu quickly killing people.

Severe flu epidemic in 1918 in Spain (Photo: fluwikie)

Influenza virus

Influenza viruses are divided into three categories: type A, B and C. Type A viruses, affecting chickens, ducks, pigs, and whales, as well as humans are the most dangerous types. Type A virus is divided into groups based on two proteins: haemaglutinin (HA) and neuraminidase (NA) around the surface of the virus. Scientists have discovered 16 types of HA (H1-H16) and 9 types of NA (N1-N6). This means that all 144 types of influenza A viruses are present, but only three types of infections (H1N1, H1N2, H3N2) are now known to be transmitted between humans.

Avian influenza belongs to micro-type

Virus causes flu in Spain in 1918
(Photo: zkea)

rus H5N1, scientists are concerned that the H5N1 virus will join the list of infectious viruses among humans. This bird flu first appeared in 1997 in Hong Kong, killing thousands of chickens and 6 victims. After the government destroyed more than 1.5 million chickens, the epidemic ended but the H5N1 bird flu is still circulating. In February 2004, a man died of bird flu in Hong Kong, then in January 2004, avian influenza killed chickens in South Korea, Vietnam, Japan and Thailand. At the end of February 2004, a total of 28 people were infected with H5N1, of which only 7 survived. Bird flu quickly spreads through Cambodia, Laos and Indonesia .

Through migratory birds from one place to another infected with the flu, bird flu has spread rapidly. At the end of 2005, it spread to Turkey, and recently in February 2006 spread through Nigeria (Africa), Bulgaria, France.

Can H5N1 bird flu become deadly epidemic like 1918 Spanish flu?

The Spanish flu virus is one of the variants of the H1N1 virus. It is now known that the Spanish virus is from birds jumping over people through the latest research recently. The sequence of the sequenced Spanish virus shows that the genetic system of the current bird flu virus in Asia has genetic changes that are very similar to the Spanish virus that causes a very fatal infection. fast. Only a few specific proteins on the viral protein system turn viruses into killer viruses. The Spanish virus is very different from the flu virus, which usually infects cells deep in the lungs and lung cells around the air sacs, which are normally not attacked by regular flu viruses.

H1N1 virus (Photo: spiegel)

In the laboratory, different from normal viruses, Spanish viruses and poultry viruses on humans now kill mice when they are infected. However, the untreated avian influenza virus is now spread from person to person.

In 1995, the scientist Taubenberger of the Department of Molecular Pathology (US) had the idea of ​​finding the Spanish virus to study again, hoping that the 1918 virus would show genetic changes. making human-to-human transmission happen, thereby helping people find ways to prevent the epidemic before they spread everywhere. This is a very important scientific work to find dangerous viruses and methods to expire them. In 1918, the virus was not scientifically discovered. How can scientists today find the Spanish virus and reconstruct its genetic structure?

Mr. Taubenberger recalled that his institute was working on a warehouse of cells from autopsies, set up under A. President Lincoln, who ordered every time a military doctor diagnosed and Taking tissue cells, a cell sample must also be sent and stored at the Military Hospital. Mr. Taubenberger wanted to know that he could find lung cells from soldiers who died in the 1918 flu pandemic and then took out the virus to study. He found tissue from two soldiers, whose lung tissue samples soaked with formalin in wax blocks. These lung tissue cells have been stored and have not been used for nearly 80 years, but of which the virus has been broken and degraded, only a few viral molecules remain. Fortunately, he had another third tissue, from a woman who had died in the cold Alaska area when the flu spread to her village, killing 72 adults leaving only 5 survivors.

Scientist Jeffery Taubenberger studied the virus that caused influenza in Spain in 1918 (Photo: gazette)

All victims were buried in a mass grave under permafrost. A retired pathologist, John Holtin, upon hearing about the work Taubenberger was studying, he spends his own money from San Francisco where he stayed at the grave in Alaska and with the approval of the village, took samples of frozen lung cells, sent to Mr. Taubenberger. Taubenberger's group for nearly 10 years has taken and reconstructed the genes of the Spanish virus. They published the genetic sequence of eight viral genes in Nature and Science journals.

In August 2005, Mr. Tumpey and his colleagues at the Center of Disease Control used information from the genes published by Taubenberger to reconstruct the 1918 virus. What happens if the mice in the lab and lung tissue in people infected with the 1918 virus they reconstruct. The scientists were very careful, they used a special laboratory to protect the researchers and prevent the spread of the reconstructed 1918 virus. They also questioned whether the 1918 virus was still lethal if they replaced some of the genes of the 1918 virus remodeling genes with the current normal influenza virus gene. Scientists have begun to explore the secrets of the 1918 virus.

In gene exchange experiments, they replaced the 1918 virus hemagglutini gene with the hemaglutini gene from the most recent influenza virus in humans. The unexpected result was that the reconstructed 1918 virus no longer developed in rat lungs and killed mice. And they cannot attach to lung tissue in humans in the laboratory. The most important is the protein on the deadly 1918 virus hemagglutini gene with only the proteins of avian influenza in two amino acids. This shows the dangers and unpredictable harms of the current bird flu virus if the hemagglutini gene on the virus is deformed through mutations or gene exchange with other human viruses to become the hemaglutini gene on the 1918 virus.

Diseases transmitted from animals to humans

Jared Diamond showed that when humans tamed animals into cattle, this close contact caused many infectious diseases caused by animals and viruses from animals. new environment in people. Smallpox and pulmonary tuberculosis are caused by bacteria from cows to humans adapting to human-to-human transmission. AIDS caused by viruses starts from monkeys jumping to humans, malaria caused by protozoa Falciparum malaria organisms originating from similar protozoa in birds.

Examining animal-to-human diseases shows that there are four evolutionary stages of human viruses and bacteria. The first stage we can see is that diseases that we sometimes get directly from livestock such as fevers from cat scratches, leptospirosis fever from pigs, dogs, cats, psittacosis fever from chickens and birds. These bacteria are still in a new state of evolution in human bacteria, they are not directly transmitted from person to person. In the second stage, the bacteria evolve to the point where they can directly infect people and cause infectious disease.

However, some of these contagious diseases disappear due to reasons such as the disease that has been prevented by modern medicine or ceased when the group of infected or dead infected people cannot spread out. . For example, in 1959 in East Africa, a fever that has never been known as Ónyong-nyong has spread several million people. This disease can be derived from monkey viruses and transmitted to humans from mosquitoes. Because patients recover quickly and become immune, this new disease disappears quickly.

Hygienic health workers during the Lassa fever outbreak in Nigeria in 1969 (Photo: terasz) The third stage in the evolution of diseases transmitted by mammal microorganisms is that they are present in humans and not yet. disappears, can recur very quickly, not knowing when. Like murderous Lassa fever must be caused by a virus from mice, which spread very quickly in Nigeria in 1969 so that hospitals have to close down only one case of hospitalization. The last stage of evolution is infectious diseases that have occurred in people many times and still remain, they have been firmly established in the society of people after having gone through many stages of evolution jumping from animals to humans and self arising from people through people.

Coping and prevention of bird flu

In the latest study published in the Journal of the Academy of Sciences in the US, after genetic analysis of H5N1 viruses from birds and birds in China showed that the virus was present and spread in southern China. from a decade ago. So it can be assured that South China is the starting point, generating H5N1 bird flu.

  Scientists also showed that migratory birds played an important role in the spread and spread of poultry viruses around the world. In South China, many healthy poultry are immune but still carry the virus. This is a big problem that must be solved to prevent spread to poultry that have not been sick elsewhere. After analyzing the genetic sequence of the H5N1 virus in wild birds, chickens in the Hong Kong swamp, Pu Yang Lake in eastern China and the chicken and duck markets in South China, the researchers showed, through interrelated diagrams of viruses, poultry from South China have infected ducks in early 2005.

These mallards brought the virus to Pu Yang Lake in eastern China, and from there went to Qinghai Lake, western China, c. Migratory birds have played an important role in the spread and spread of poultry viruses around the world. (Photo: cbsnews) The yoke of more than 1700km killed many of these protected and sheltered birds. From Qinghai Lake, the virus is transmitted to Russia and other countries in the Middle East, Mongolia and Europe.

From South China, there have been many times of contagion from neighboring Vietnam and beyond (Indonesia). In these places, the virus establishes a new residence and exacerbates preventive measures to prevent bird flu from jumping to people. Therefore, in order to prevent and control pandemic flu, it is necessary to blockade the source of the epidemic in South China first.

In Saigon and many provinces, I noticed that there are many posters and banners informing people about the dangers that avian influenza can spread to people and how to take precautions, from basic information such as thorough cooking. Chicken, H5N1 flu when spread through humans and infectious will kill up to 2 million people in Vietnam, transport vehicles carrying poultry must avoid peak traffic hours and certain paths. It must be said that in Vietnam there is an active implementation of preventing bird flu. The World Health Organization (World Health Organization) has appreciated the achievement of Vietnam in dealing with bird flu and considers Vietnam a model for developed countries to follow.

Also according to the study mentioned above, genetic analysis of virus families shows that there are many different types in birds and birds, while previous virus analysis on infected people shows only two types. different. Preventive and curative drugs for a virus may only be a little or ineffective with other viruses. Researchers suggest that a number of different drugs are manufactured and pre-reserved to be available when dispersal spreads around the world in humans.