From Spaniards to Birds: Known Flu Outbreaks
Chamber for the sick in the "Spanish" / photo: Wikipedia
Outbreaks of influenza have been known for a long time, but became famous since the beginning of the 20th century, when the Spaniard took millions of lives. During the 1918-1919 pandemic, it was estimated that 550 million people, or 29.5% of the then world population.
It should also be taken into account that this happened immediately after the end of the First World War, therefore there was unsanitary conditions everywhere, bad food or its absence. The disease spread rapidly among refugees in the camps. About 50-100 million people died, that is, 2.7-5.3% of the total population (10-20% mortality). Basically, the victims were young people aged 20-40 years who were previously healthy (the usual seasonal flu kills mostly elderly people and children).
Due to the development of transport (trains, first cars, ships and airships), the epidemic has spread throughout the world and has become a pandemic. The gene structure of the H1N1 virus was discovered in 2002. After that, smaller epidemics were in 1957 (H2N2) and in 1968-1970 (H3N2).
The new "world fame" for the H1N1 flu was brought by the 21st century. In 2009, the so-called "swine flu", which was found in pigs, spread throughout the world. It is interesting that if pork is thermally treated properly, it cannot be a source of infection. The transmission to the person from the animal in this case is weakly recorded, but still possible. More virus is transmitted by airborne droplets. Even if transmission did occur, the virus does not always cause a disease; it can only be detected in antibodies in the blood. Whether pigs were the ultimate zoonosis (an animal that transfers the virus from itself to humans) is still not known for certain. Animals themselves may be infected with the human influenza virus.
And yet, a new world epidemic has occurred, although the previous season was rather “soft” in the world, without going beyond the usual framework for influenza, there were fewer deaths due to the new vaccine. In the spring of 2009, an outbreak of influenza occurred in Mexico City (Mexico), which quickly spread to the United States, and then to other countries of the world. As during the "Spanish", the virus killed mostly young people 25-45 years old. According to WHO, more than 221 thousand people fell ill, of whom nearly two thousand died.
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In addition to the "swine" flu, which was active in 2009, also known is the "bird" flu – H5N1. He (so far) does not have an epidemic among people, facts of transmission from person to person are also not found. It is a virus with a high, almost 100% mortality rate for animals. Since it actively mutates among birds, it is considered one of the main epidemiological threats to the world not only from a medical, but also anti-terrorism point of view.
Coronaviruses: New Threats
More than a decade ago, the first coronavirus epidemic occurred / photo: Getty Images
This family of viruses with 39 types first became known in 1965, it was found in a patient with acute rhinitis. The name was given due to the characteristic appearance resembling a crown. It affects the respiratory, digestive and nervous systems of both animals and humans. Usually, these are bronchitis and pneumonia with difficulty breathing.
Two epidemics of viral pneumonia have passed: SARS and MERS. The first means "severe acute respiratory syndrome", the second – "Middle East respiratory syndrome." SARS is a highly infectious disease. It is capable of widespread and high mortality, including in hospitals, and is a variant of coronavirus infection. It is transmitted by airborne droplets or through animals (moreover, causing them more severe illnesses than humans).
It is known in the world as “SARS” and also began in the PRC, in Foshan Province, back in 2002 with a “zero patient” – a farmer. However, then China did not inform WHO for a year about the course of SARS. In 2003, a businessman died in Hanoi, Vietnam – he became ill on a flight to Singapore from China. Interestingly, at first SARS was mistaken for … "bird flu." Zoonosis of the infection has not been proven (although bats and civets are suspected), the patient is considered the main source of infection.
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The Italian Carlo Urbani himself, who began research on the virus, also died from it. When WHO called for the fight against the virus, it was already in 32 countries, including the United States. On March 21, 2003, the coronavirus that caused the epidemic was isolated, but some scientists believe that there were other pathogens. In total, 8461 cases were detected in 35 countries, of which 916 were fatal (10% mortality).
After 10 years, a new species of coronavirus caused an outbreak in the Middle East. The first case occurred in 2012 with a 49-year-old Qatar citizen who came to Britain. He got sick when he was in Saudi Arabia. As of 2019, 2494 cases have been recorded in the world, of which 858 deaths. Of these, 185 cases (36 dead) occurred in South Korea in 2015. A number of studies have shown that camels can be a secondary source of the virus. The primary reservoir has not yet been established, as well as whether a person can become one. The clinical picture is still poorly understood, but similar to SARS: shortness of breath, cough, sometimes diarrhea. If there is a suspicion that the patient has been in the region where this virus spread, or has contacted patients with it, then additional diagnostics are needed.
Specific treatment, like vaccines, has not yet been developed for coronaviruses. Meanwhile, he returned to China.
Wuhan virus: is a new epidemic possible
Wuhan was the last place where the coronavirus broke out / photo: Getty Images
Even before the holidays, December 31, 2019, a new disease appeared on the illegal wildlife and meat market in Wuhan in eastern China. Such places in China are called "wet markets" – there you can buy a living animal and divide it into pieces there to carry or cook. Of course, viruses, germs and bacteria could be spread there. Beijing has already survived the H7N9 bird flu, after which it closed all markets where live birds were sold, thus stopping the spread of the disease.
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Almost immediately, it became clear that this is another new type of coronavirus, now it is called 2019-nCoV. The Wuhan virus has 70% similarity with SARS, it is part of the same virus line, but still differs enough to be considered new.
In Wuhan, the virus was detected in 41 people. The first death occurred on January 9th. Now officially known about more than 600 patients (figure, scientists from Great Britain and Hong Kong, is understated, while the real one is closer to 2000), 95 in critical condition, 17 were killed. Some who died from new pneumonia also had other diseases, which complicated the fight against the new one. The situation forced the Chinese authorities to grant the disease a hazard class B. Wuhan, where 11 million people live, and neighboring cities are thus quarantined, Wuhan full. All New Year celebrations are canceled.
Outside the PRC, cases have been confirmed in South Korea, Japan, the USA, Thailand, Macau, Hong Kong, and Taiwan.
It is still unknown which animal the virus passed from to humans, but snakes are suspected. Human-to-human transmission, although limited, has been confirmed by infection of medical staff (as is the case with SARS). There are reports that 14 doctors became infected from one patient. This allows you to identify the so-called "super-distributor" – a person who has infected more than 10 others. And this is already very similar to what happened with SARS. On average, with the worst strains of the flu, one person could infect about two others. With SARS – less than one person per 10 thousand. But even 1 or 2 percent of mortality is already a very serious situation, as we saw with the "Spaniard". As soon as it becomes clear how infectious the Wuhan virus is, it will become clear how deadly it is.
Unlike 2003, now WHO and countries are better prepared to fight coronavirus. There are known therapeutic options for treating patients, improved sanitary protocols. All of this should help contain the virus. In addition, unlike influenza, coronaviruses do not have the potential to create a pandemic, expert virologists are sure. Scientists have already developed 15 viral genomes, including Wuhan, but almost did not find mutual mutations. Now even the incubation period and mortality rate are unknown. Therefore, it can be expected that the virus will spread further. How dangerous this is, time and research will show.