The worst epidemics in human history. The largest epidemics in the history of the USSR
Infectious diseases have decimated mankind for many centuries. Epidemics destroyed entire nations and sometimes claimed even more lives than war, because doctors did not have antibiotics and vaccines in their arsenal to fight diseases. Today, medicine has stepped far forward and it seems that now a person has nothing to fear. However, most viruses can adapt to new conditions and again become a danger to our lives. Consider the worst epidemics in the history of mankind and hope that we do not have to face such terrible things.
1. Malaria
Malaria is considered one of the oldest diseases. According to some scientists, it was from this disease that the Egyptian pharaoh Tutankhamun died. Malaria, caused by the bite of a mosquito, affects up to 500 million people every year. Malaria is especially common in African countries, this is due to the presence of polluted stagnant water and the reproduction of mosquitoes in it.
After the bite of an infected mosquito, the virus enters the human blood and begins to actively multiply inside the red blood cells, thereby causing their destruction.
2. Smallpox
To date, smallpox is absent in nature and is the first disease completely defeated by man.
The most terrible was the smallpox epidemic in America. The virus came to North and South America with European settlers. At the beginning of the 16th century, the smallpox virus caused a 10-20-fold decrease in the population of America. Smallpox claimed the lives of about 500 million people. Scientists suggest that the smallpox virus first appeared in ancient Egypt. Evidence of this was obtained after studying the mummy of Pharaoh Ramses V, who died in 1157 BC. e., on which traces of smallpox were found.
3. Plague
The most famous pandemic in history is the Black Death. An outbreak of the bubonic plague decimated the population of Europe from 1346 to 1353. The skin of those infected was covered with inflamed and swollen lymph nodes. The patients suffered from a terrible fever and coughed up blood, which meant that the disease had hit the lungs. Mortality from bubonic plague in the Middle Ages was about 90% of those infected. According to historians, the "Black Death" claimed the lives of 30 to 60% of the population of Europe.
4. Plague of Justinian
The Black Death was not the only major plague in human history. In the VI century, the so-called "Justinian Plague" raged, this epidemic is considered to be the first epidemic that was officially recorded in historical documents. The disease struck the Byzantine Empire around 541 AD. e. and is believed to have claimed the lives of 100 million people. Outbreaks of the "Justinian Plague" arose for another 225 years before disappearing completely. It is assumed that the disease came to Byzantium from China or India along the sea trade routes.
5 Spanish Flu
The Spanish flu epidemic, which caused the death of a third of the world's population, began in 1918. According to some reports, the disease killed between 20 and 40 million people in two years. It is assumed that the virus appeared in 1918 in China, from where it got to the United States, after which it spread by American soldiers throughout Europe. By the summer of 1918, influenza had spread throughout Europe. The governments of the countries categorically forbade the media to induce panic, so the epidemic became known only when the disease reached Spain, which remained neutral. Hence the name "Spanish flu". By winter, the disease swept almost the entire world, without affecting Australia and Madagascar.
Attempts to create a vaccine have not been successful. The Spanish flu epidemic lasted until 1919.
6. Plague of Antoninus
The Plague of Antoninus, also known as the Plague of Galen, raged through the Roman Empire from 165 to 180 AD. e. During the epidemic, about 5 million people died, including several emperors and members of their families. The disease was described by Claudius Galen, who mentioned that a black rash appeared on the body of those who fell ill, which suggests that the epidemic was caused by smallpox, and not plague.
7. Typhus
There have been several epidemics of typhus in history. The disease caused the greatest damage during the First World War, causing the death of more than 3 million people. The typhoid vaccine was invented during World War II.
8. Tuberculosis
Tuberculosis has been the cause of death for countless people throughout history.
The worst epidemic of tuberculosis, known as the Great White Plague, began in Europe in the 1600s and raged for more than 200 years. The disease has claimed the lives of about 1.5 million people.
In 1944, an antibiotic was developed to help effectively fight the disease. But, despite the development of medicine and treatment, every year about 8 million people worldwide fall ill with tuberculosis, a quarter of whom die.
9. Swine flu
The swine flu pandemic, which lasted from 2009 to 2010, killed 203,000 people worldwide.
This viral strain consisted of unique influenza virus genes that had not previously been identified in either animals or humans. The closest to the swine flu virus were the North American swine H1N1 virus and the Eurasian swine H1N1 virus.
Swine flu in 2009-2010 is considered one of the worst modern pandemics, and shows how vulnerable modern people are to certain flu strains.
10. Cholera
One of the first modern pandemics is the cholera outbreak from 1827 to 1832. Mortality reached 70% of all infected, which amounted to more than 100,000 people. The disease came to Europe through British colonists returning from India.
For a long time it seemed that cholera had completely disappeared from the face of the earth, but the outbreak of the disease began in 1961 in Indonesia and spread to most of the world, killing more than 4,000 people.
11. Plague of Athens
The Athenian plague began around 430 BC. e. during the Peloponnesian War. The plague killed 100,000 people in three years, it should be noted that at that time this number was about 25% of the total population of Ancient Athens.
Thucydides gave a detailed description of this plague to help others identify it later. According to him, the epidemic manifested itself in a rash on the body, high fever and diarrhea.
Some scientists believe that smallpox or typhus were the cause of the epidemic in ancient Athens.
12. Moscow plague
In 1770, an outbreak of bubonic plague occurred in Moscow, which killed between 50,000 and 100,000 people, that is, a third of the city's population. After the epidemic in Moscow, bubonic plague disappeared from Europe.
13. Ebola virus
The first cases of Ebola were detected in Guinea in February 2014, it was here that the epidemic began, which lasted until December 2015, and spread to Liberia, Sierra Leone, Senegal, the USA, Spain and Mali. According to official figures, 28,616 people fell ill with Ebola and 11,310 people died.
The disease is highly contagious and can cause damage to the kidneys and liver. Ebola fever requires surgical treatment. A vaccine against the disease was discovered in the US, but because it is extremely expensive, it is not available worldwide.
14. HIV and AIDS
AIDS is the cause of death for more than 25 million people. Scientists believe the disease originated in Africa in the 1920s. HIV is a viral form of the disease and attacks the human immune system. Not everyone infected with HIV develops AIDS. Many people with the virus are able to lead normal lives thanks to the use of antiretroviral drugs.
In 2005, 3.1 million people died of AIDS. The average death rate per day was about 8,500.
The death of one person is a tragedy. The death of millions is already a statistic. Alas, in the history of our civilization there have been such large-scale epidemics that even the most seasoned statistician would have a chill.
1. Plague of Thucydides
Very little information has been preserved about the epidemics of antiquity. Probably the largest of these was the Thucydides Plague that broke out in Athens from 431 to 427 BC. An epidemic began during the Peloponnesian War, when Athens was overwhelmed with refugees. Several outbreaks of the disease cost the city thirty thousand inhabitants. Among the victims of the disease was one of the fathers of Athenian democracy, Pericles. The Greek historian Thucydides, who himself suffered from the disease, but survived, spoke in detail about the tragedy of Athens. Modern scientists argue that the cause of the epidemic was not the plague, but a combination of measles and typhus.
2. Plague of Justinian
The Plague of Justinian is the oldest pandemic about which more or less reliable information has come down to us. The disease originated in the Nile Delta. Plague carriers, rats and fleas, sailed from plague-stricken Egypt to Constantinople on ships with wheat. The beginning of the nightmare occurred just during the reign of the Byzantine emperor Justininan I. The first plague fire raged on the territory of the then civilized world for almost two centuries, from 541 to 750 AD. In Europe, died, according to various sources, from 25 to 50 million people. In North Africa, Central Asia and Arabia - twice as much.
3. Smallpox
China and Japan got no less than Europe. In the 4th century, an epidemic of smallpox swept across China, in the 6th century it reached Korea. In 737, smallpox in Japan killed about 30% of the population. The disease left such a deep mark in the history of the Asian peoples that the Indians even had a separate goddess of smallpox - Mariatale. But in 1796, the English physician Edward Jenner invented vaccination. And now it is officially believed that the variola virus exists in only two laboratories in the world.
4. Black Death
The second tour of the plague around the world happened in the Middle Ages. Starting this time in China and India, the epidemic has swept across Asia, North Africa and even reached Greenland. Because of the disease, half of the population of Italy died out, every nine out of ten inhabitants of London and more than a million inhabitants of Germany became victims of the disease. By 1386, only five people remained alive in the Russian city of Smolensk. In total, Europe has lost about a third of the population. Modern sanitation rules and ... fires came to the rescue of people. So, in London, the plague disappeared after a great fire in 1666.
5. English sweat
The most famous epidemic with a still unknown cause. Tudor England suffered the most between 1485 and 1551. In August 1485, Henry Tudor won the Battle of Bosworth, entered London and became King Henry VII. His French and Breton mercenaries brought an unknown deadly disease to the island. Francis Bacon and Thomas More wrote about this disease. Historians have described it as the English plague or relapsing fever. But the reasons for the English sweat that raged in Britain, the Holy Roman Empire, the Grand Duchy of Lithuania, Norway and Sweden are still unclear.
6. Dance of St. Vitus
In July 1518, in Strasbourg, a woman named Troffea went out into the street and began to perform dance steps, which continued for several days. By the end of the first week, 34 local residents had joined. Then the crowd of dancers grew to 400 participants. This strange disease was called "dancing plague" or "epidemic of 1518". Experts believe that the cause of such mass phenomena was the spores of mold that formed in the stacks of wet rye that got into the bread. During this most epidemic in world history, hundreds of people literally danced to death.
7. Cholera
The cholera pandemic started in 1817 in Southeast Asia and claimed the lives of forty million people in India alone. Soon cholera reached Europe. Despite the fact that medicine had made great progress by that time, about seven thousand people died from cholera in London alone, and more than a hundred thousand in Europe as a whole. Five outbreaks of the disease also occurred in Russia in the first half of the 19th century. One of them forced Alexander Pushkin to sit without getting out at the Boldino estate, waiting out the cholera quarantine. Do I need to explain what the words "Boldino Autumn" mean for Russian literature?
8 Spanish Flu
The Spanish flu was probably the most massive influenza pandemic in human history. In 1918-1919, in just eighteen months, up to 100 million people, or 5% of the world's population, died. About 30% of the world's population fell ill with the "Spanish flu". The epidemic began in the last months of the First World War and quickly overshadowed this largest bloodshed in terms of casualties. In Barcelona, 1,200 people died every day. In Australia, a doctor counted 26 funeral processions in one hour on the street alone. Entire villages from Alaska to South Africa died out.
9. Ebola
An outbreak of this disease was first documented in 1976 in neighboring areas of Sudan and Zaire. Oblivion was named after a river in that region of Africa. The Ebola virus is incredibly contagious, with fever death rates reaching 90% even today. There is still no specific treatment or vaccine for Ebola. The only way to control outbreaks of an epidemic is a strict quarantine. And despite this, in 2014, the worst Ebola epidemic in history broke out in West Africa. The number of victims has already exceeded a thousand.
10 Bird Flu
The first epidemic of the post-information era. Its appearance and development took place with television cameras turned on and broadcast on the Internet in real time. Bird flu has been known about since the 19th century. However, the first case of human infection with the H5N1 influenza strain was recorded in Hong Kong only in 1997. The whole world put on gauze bandages, switched to pork and raced for injections. Vaccination, personal hygiene and quarantine measures have taken their toll: according to the World Health Organization, from February 2003 to February 2008, only 227 cases of human infection with the avian influenza virus became fatal.
When we study history, we pay little attention to pandemics, and yet some of them have claimed more lives and influenced history more than the longest and most destructive wars. According to some reports, no less people died in a year and a half of the Spanish flu than during the entire Second World War, and numerous outbreaks of the plague prepared people's minds for the overthrow of absolutism and the transition from the Middle Ages to the New Age. The lessons of pandemics have cost humanity too much, and, alas, even now, in the era of advanced medicine, we continue to pay these bills.
Children's writer Elizaveta Nikolaevna Vodovozova was born in 1844 - 2 years before the third cholera pandemic (the deadliest of all) appeared in Russia. The epidemic ended only in the early 1860s, during which time it claimed more than a million lives in Russia and one and a half million in Europe and America. Elizaveta Nikolaevna recalls that in just a month cholera took 7 members of her family. Later, she explained such a high mortality rate by the fact that the household did not follow the simplest rules of prevention: they spent a lot of time with the sick, did not bury the dead for a long time, did not follow the children.
But one should not accuse the writer's family of frivolity: despite the fact that the cholera that came from India was already familiar to Europeans, they knew nothing about the causative agents of the disease and the ways of penetration. It is now known that the cholera bacillus, living in dirty water, provokes dehydration, due to which the patient dies a few days after the onset of the first symptoms. In the middle of the 19th century, no one suspected that sewage was the source of the disease, and people needed to be treated for dehydration, and not for fever - at best, the sick were warmed up with blankets and heating pads or rubbed with all kinds of spices, and at worst, they bled, they gave him opiates and even mercury. The cause of the disease was considered the stench in the air (which, however, brought some benefits - residents removed garbage from the streets and installed sewers to get rid of the destructive smell).
The English doctor John Snow was the first to pay attention to water. In 1854, cholera killed over 600 people in Soho, London. Snow drew attention to the fact that all the sick people drank water from the same pump. Soho lived in the worst conditions of unsanitary conditions: the area was not connected to the city's water supply, so drinking water was mixed with contaminated sewage. Moreover, the contents of the overflowing cesspools fell into the Thames, which is why the cholera bacillus spread to other areas of London.
For a modern person, it is obvious that the most terrible epidemics in the history of mankind were provoked precisely by such cases of blatant unsanitary conditions, but the inhabitants of the 19th century were in no hurry to believe the far-sighted Snow - the version that contaminated air was to blame for everything was too popular. But in the end, the doctor persuaded the inhabitants of Soho to break the handle of the ill-fated column, and the epidemic was stopped. Slowly but surely, the ideas of John Snow were adopted by the governments of different countries, and water supply systems were finally established in the cities. However, before that, 4 more cholera epidemics happened in the history of Europe.
Valentin Kataev in the story "Sir Henry and the Devil" described one terrible disease that many Russian soldiers suffered from at the beginning of the 20th century. The patient tossed about in the heat, he was tormented by hallucinations, as if rats were wound up in his ear, which were constantly squeaking and scratching. The light of an ordinary light bulb seemed to the patient almost unbearably bright, some kind of suffocating smell spread around the room, and there were more and more rats in the ears. Such terrible torments did not seem unusual to ordinary Russian people - typhoid ones appeared in every village and every regiment. Doctors hoped only for luck, because there was nothing to treat typhus until the middle of the 20th century.
Typhus became a real scourge for Russian soldiers during the First World War and the Civil War. According to official data, in 1917-1921. 3-5 million fighters died, but some researchers who analyzed the losses in the civilian population estimate the scale of the disaster at 15-25 million lives. Typhus is transmitted to humans through body lice - it was this fact that became fatal for Russian peasants. The fact is that lice were then treated quite condescendingly, as something normal and not subject to destruction. They were among the inhabitants of peaceful villages and, of course, were bred in large numbers in conditions of military unsanitary conditions, when soldiers massively lived in places unsuitable for habitation. It is not known what losses the Red Army would have suffered during the Second World War, if in 1942 Professor Alexei Vasilyevich Pshenichnov had not made a vaccine against typhus.
When the Spanish conquistador Hernán Cortés landed on the shores of present-day Mexico in 1519, about 22 million people lived there. After 80 years, the local population barely numbered a million. The mass death of the inhabitants is not connected with the special atrocities of the Spaniards, but with a bacterium that they unknowingly brought with them. But only 4 centuries later, scientists found out which disease wiped out almost all indigenous Mexicans. In the 16th century it was called cocolizzli.
It is rather difficult to describe the symptoms of a mysterious disease, since it took a wide variety of forms. Someone died from a severe intestinal infection, someone especially suffered from fever syndromes, while others choked in the blood accumulated in the lungs (although the lungs and spleen failed in almost everyone). The disease lasted 3-4 days, the mortality rate reached 90%, but only among the local population. The Spaniards, if they picked up cocolizzli, then in a very mild, non-lethal form. Therefore, scientists came to the conclusion that the Europeans brought the dangerous bacterium with them, who probably developed immunity to it long ago.
At first it was thought that cocolizzli was typhoid fever, although some symptoms contradicted this conclusion. Then scientists suspected hemorrhagic fever, measles and smallpox, but without DNA analysis, all these theories remained highly controversial. Studies conducted already in our century have established that the Mexicans of the colonization period were carriers of the bacterium Salmonella enterica, which causes paratyphoid C. In the DNA of people who lived in Mexico before the arrival of the Spaniards, there is no bacteria, but Europeans were ill with paratyphoid back in the 11th century . Over the past centuries, their bodies have become accustomed to the pathogenic bacterium, but it almost completely destroyed the unprepared Mexicans.
spanish flu
According to official figures, the First World War claimed about 20 million lives, but this should be added another 50-100 million people who died due to the Spanish flu pandemic. The deadly virus, which originated (according to some sources) in China, could well have died there, but the war spread it around the world. As a result, in 18 months, a third of the world's population fell ill with the Spaniard, about 5% of the people on the planet died, choking in their own blood. Many of them were young and healthy, had excellent immunity - and literally burned out in three days. History did not know more dangerous epidemics.
"Pneumonic plague" appeared in the provinces of China as early as 1911, but then the disease did not have the opportunity to get further, and it gradually faded away. A new wave came in 1917 - the world war made it a global epidemic. China sent volunteers to the West, which was in dire need of workers. The Chinese government decided to quarantine too late, so sick lungs arrived along with the working hands. And then - a well-known scenario: in the morning in the American military unit, symptoms appeared in one person, by the evening there were already about a hundred patients, and a week later there would hardly be a state in the United States that was not touched by the virus. Together with the British troops stationed in America, the deadly flu arrived in Europe, where it reached first France and then Spain. If Spain was only 4th in the chain of the disease, then why was the flu called "Spanish"? The fact is that until May 1918, no one informed the public about the terrible epidemic: all the “infected” countries participated in the war, therefore they were afraid to announce a new misfortune to the population. Spain remained neutral. About 8 million people fell ill here, including the king, that is, 40% of the population. It was in the interests of the nation (and of all mankind) to know the truth.
The Spaniard killed almost instantly: on the first day the patient did not feel anything but fatigue and headache, and the next day he was constantly coughing up blood. Patients died, as a rule, on the third day in terrible agony. Before the advent of the first antiviral drugs, people were absolutely helpless: they limited contacts with others in every possible way, tried not to go anywhere once again, wore bandages, ate vegetables and even made voodoo dolls - nothing helped. But in China, by the spring of 1918, the disease began to decline - the inhabitants again developed immunity against the Spanish flu. Probably the same thing happened in Europe in 1919. The world got rid of the influenza epidemic - but only for 40 years.
Plague
“On the morning of April 16, Dr. Bernard Rieux, leaving his apartment, stumbled on a dead rat on the landing” - this is how the beginning of a big disaster is described in the novel “The Plague” by Albert Camus. The great French writer knowingly chose this deadly disease: from the 5th century. BC e. and up to the 19th century. n. e. there are more than 80 plague epidemics. This means that the disease has been with humanity more or less always, sometimes subsiding, sometimes attacking with renewed vigor. Three pandemics are considered the most ferocious in history: the Plague of Justinian in the 5th century, the famous "Black Death" in the 14th century, and the third pandemic at the turn of the 19th-20th centuries.
Emperor Justinian the Great could remain in the memory of posterity as a ruler who revived the Roman Empire, revised Roman law and made the transition from antiquity to the Middle Ages, but fate decreed otherwise. In the tenth year of the emperor's reign, the sun literally dimmed. Ash from the eruption of three major volcanoes in the tropics polluted the atmosphere, blocking the path of the sun's rays. Just a few years later, in the 40s. In the 6th century, an epidemic came to Byzantium, the equal of which the world had never seen. For 200 years of the plague (which at times covered the entire civilized world, and all other years existed as a local epidemic), more than 100 million people died in the world. Residents were dying from suffocation and ulcers, from fever and insanity, from intestinal disorders and even from invisible infections that killed seemingly completely healthy citizens on the spot. Historians noted that the sick did not develop immunity to the plague: those who survived the plague once or even twice could die, becoming infected again. And after 200 years, the disease suddenly disappeared. Scientists are still wondering what happened: the finally retreating ice age took the plague with it, or did people still develop immunity?
In the XIV century, a cold snap returned to Europe - and with it the plague. The rampant nature of the epidemic was facilitated by complete unsanitary conditions in the cities, on the streets of which sewage flowed in streams. Contributed their mite of war and famine. Medieval medicine, of course, could not fight the disease - doctors gave herbal infusions to patients, cauterized buboes, rubbed ointments, but all in vain. The best treatment turned out to be good care - in very rare cases, the sick recovered, simply because they were properly fed and kept warm and comfortable.
The only way to prevent it was to limit contact between people, but, of course, panic-stricken residents fell into all sorts of extremes. Someone began to actively atone for sins, fasting and self-flagellation. Others, on the contrary, before imminent death decided how to have fun. Residents greedily grabbed every opportunity to escape: they bought pendants, ointments and pagan spells from scammers, and then immediately burned witches and staged Jewish pogroms to please the Lord, but by the end of the 50s. the disease gradually disappeared on its own, taking with it about a quarter of the world's population.
The third and final pandemic was nowhere near as devastating as the first two, but it still killed nearly 20 million people. The plague appeared in the middle of the 19th century in the Chinese provinces - and did not leave their borders until almost the end of the century. 6 million Europeans were ruined by trade ties with India and China: at first, the disease slowly crept up to local ports, and then sailed on ships to the shopping centers of the Old World. Surprisingly, the plague stopped there, this time without making its way into the depths of the continent, and by the 30s of the 20th century it had almost disappeared. It was during the third pandemic that doctors determined that rats were carriers of the disease. In 1947, Soviet scientists first used streptomycin in the treatment of plague. The disease that destroyed the population of the Earth for 2 thousand years was defeated.
AIDS
Young, slender, very attractive blond Gaetan Dugas worked as a flight attendant for Canadian Airlines. It is unlikely that he was going to ever get into history - and yet he did, albeit by mistake. Gaetan from the age of 19 led a very active sex life - according to him, he slept with 2,500 thousand men throughout North America - this was the reason for his, unfortunately, notorious fame. In 1987, 3 years after his death, journalists called the young Canadian "patient zero" of AIDS - that is, the person who started the global epidemic. The results of the study were based on a scheme in which Dugas was marked with a "0", and rays of infection radiated from him throughout all the states of America. In fact, the “0” sign in the scheme did not mean a number, but a letter: O - out of California. In the early 80s, in addition to Dugas, scientists examined several more men with symptoms of a strange disease - all of them, except for the imaginary "patient zero", were Californians. The real number of Gaetan Dugas is only 57. And HIV appeared in America back in the 60s and 70s.
HIV was transmitted to humans from monkeys around the 1920s. XX century - probably during the butchering of the carcass of a dead animal, and in human blood it was first discovered in the late 50s. Just two decades later, the virus became the cause of the AIDS epidemic - a disease that destroys the human immune system. In 35 years of activity, AIDS has killed about 35 million people - and so far the number of those infected is not falling. With timely treatment, the patient can continue a normal life with HIV for several decades, but it is not yet possible to completely get rid of the virus. The first symptoms of the disease are persistent fever, prolonged intestinal disorders, constant cough (in the advanced stage - with blood). The disease, which in the 80s was considered the scourge of homosexuals and drug addicts, now has no orientation - anyone can catch HIV and in a few years get AIDS. That is why it is so important to follow the simplest rules of prevention: avoid unprotected sexual intercourse, check the sterility of syringes, surgical and cosmetic instruments, and regularly take tests. There is no cure for AIDS. Having shown negligence once, you can suffer from the manifestations of the virus for the rest of your life and sit on antiretroviral therapy, which has its own side effects and is definitely not a cheap pleasure. You can read more about the disease.
An epidemic is the spread of an infectious disease that is significantly higher than the normal incidence in the area. For the emergence of an epidemic, a number of prerequisites are necessary: violation of sanitary rules, the presence of sources of infection, for transmissible infections and susceptible populations, insufficient preventive work by health authorities, etc.
The usual (minimal) incidence for a given area and under given historical conditions is called sporadic. These are most often unrelated isolated cases of diseases. Only in relation to certain infectious diseases, such as influenza, sporadic incidence is expressed by a sufficiently large number of cases.
An increase in the incidence, limited to a small area [one settlement, part of a city (village), hostel, barracks, etc.] and occurring for a short time, is commonly called an epidemic outbreak.
The spread of an infectious disease over a large area, sometimes in several countries or on several continents with a mass defeat of the population, is called.
In cases where infectious morbidity in a certain area is recorded constantly, for many years, it is customary to speak of endemia or endemicity of a particular disease. If the incidence in a certain area is recorded for a long time due to poor sanitary conditions (dysentery with poor water supply and cleaning, with lice), then they talk about the so-called statistical endemicity. If this incidence is associated with the presence of certain natural conditions (constant circulation of the pathogen among marmots, ground squirrels or gerbils, the presence in the area of such guardians of the infection as a tick at or, etc.), then they speak of the true endemicity of this disease.
Infectious diseases that are unusual, unusual for a given area (country) and imported from other, more often distant places, are called exotic (for the USSR - smallpox, etc.).
In the movement of infectious morbidity, quantitative fluctuations are observed according to the time of year (seasonality). They are due to the influence of natural conditions. So, seasonal rises in incidence can be determined by seasonal fluctuations in the activity of vectors (malaria, mosquito fever, etc.), some features of the life of animals - sources of infection, for example, during winter ground squirrels, marmots, possible human contact with them is cut off and thereby the possibility of the appearance of plague is prevented; mass murine in the autumn-winter period and the appearance of tularemia among them cause massive morbidity among people. The appearance of vegetables and fruits, their consumption without observing the rules of hygiene entails intestinal infections, etc.
An epidemic (Greek epidemia, from epi - among and demos - people) is a high degree of intensity of the epidemic process.
An epidemic process is a continuous process of transmission of infection from sick people or sick animals (sources of infection) to healthy people. According to L. V. Gromashevsky, the epidemic process is a continuous chain of infectious conditions following one after another. The intensity of the epidemic process, i.e. the degree of dynamics of infection transmission, depends on the period of incubation of the disease (the shorter this period, the faster the process of new infections), the activity and nature of infection transmission factors, and the susceptibility of the population to infection. All these elements constitute the biological essence of the epidemic process and determine its intensity.
Sociobiological factors influencing the dynamics of infection transmission include the number of people at risk of infection. With single diseases in a family or apartment, the likelihood of new infections is more or less limited. If the disease occurred in a hostel, school, kindergarten, orphanage, etc., this probability is much higher. Bacterial contamination of the water supply system threatens the health and life of an immeasurably greater number of people, etc.
Numerous other causes, representing a combination of biological and social factors, also affect the dynamics of transmission. They can be divided into two groups. The first group consists of factors that restrain, slow down the transmission of infection: low population density; absence of natural foci of transmissible infections; the stability of the local population; communal improvement of populated areas; favorable living conditions and free accommodation in dwellings; sufficiently good sanitary conditions at work; high level of sanitary culture of the population, including employees of children's institutions, food industry enterprises, public catering and food trade; the possibility of carrying out planned mass specific prevention of infections; high level of clinical and laboratory services for the population; well-organized and conducted hygienic and anti-epidemic work among the population (control over the sanitary condition, working and living conditions of the population, communal, children's institutions, public catering and the sale of food products; well-conducted surveys of epidemic foci, work in foci of infection, identification and neutralization of carriers of infection , measures against the introduction of infections from abroad, etc.), etc.
The second group consists of factors that accelerate the process of infection transmission: high population density in a given territory; the presence of natural foci of transmissible infections; the mobility of the local population (permanent or periodic replenishment of the population at the expense of visitors and other places in the country or from abroad); lack of public amenities and overcrowding in dwellings; violations of the sanitary regime of labor at work; insufficient level of sanitary culture of the population; poor organization of the vaccination business or the impossibility of carrying out mass specific prophylaxis (lack of scientifically proven means of specific prophylaxis for a number of infections, lack or shortage of drugs for mass immunization, etc.); unsatisfactory organization of clinical, laboratory and sanitary and anti-epidemic assistance to the population. The number of factors of both groups is not limited to this list.
The following degrees of intensity of the epidemic process are distinguished: sporadic incidence, focality, epidemic outbreak, seasonal epidemic, local or more widespread epidemic, pandemic. Different degrees of intensity of the epidemic process have a certain biological and social basis.
Sporadic morbidity is characterized by the registration in a given area of single infectious diseases, undoubtedly having sometimes very distant epidemiological links with each other, which is why the sources of infection in them very often cannot be found. Sporadic incidence may indicate the attenuation of the epidemic process, which may depend on many reasons, among which are the depletion of susceptible contingents of the population, the widespread use of specific prophylaxis, a progressive decrease in the number of long-term carriers of infection, the growth of the sanitary culture of the population and the communal and sanitary improvement of dwellings and populated areas , active detection of primary foci of infection and their timely and reliable neutralization, etc. Under these favorable conditions, the attenuation of the epidemic process can become stable and progress to the complete disappearance of diseases. But it can also be temporary - until the period of the next activation of the relevant infection transmission factors, until violations of the specific prophylaxis regime or the sanitary regime in the broad sense.
Focality - characterizes the intensity of the epidemic process in the focus of an infectious disease. The degree of focality is determined by the number of diseases in the epidemic focus (see). Sometimes in the epidemic focus, several homogeneous diseases occur simultaneously or within a short time. In other cases, diseases in the focus occur sequentially, one after another, at intervals equal to the incubation period of the disease. There may be other options for the occurrence of diseases in the foci. With the current level of anti-epidemic work, the incidence in the foci is often limited to one case. With simultaneous diseases, one can think of a common source of infection for all sick people and a food or water route of infection transmission. In the second case (subsequent diseases), the source of infection is the first patient in the focus with household factors of infection transmission. A consistent increase in the number of cases in the same focus characterizes the work of an epidemiologist from an unfavorable side.
An epidemic outbreak is characterized by the simultaneous or sequential appearance of diseases among people related to a common food, water supply, food supply point, simultaneous contact with patients with an airborne infection transmission mechanism, etc., but of limited, local significance.
Some authors believe that the term "epidemic outbreak" is contrived; that such group diseases are nothing but an epidemic. However, there is a significant difference between these concepts. For example, a group of diseases of local importance among people who used water from a contaminated well or from a faulty and contaminated water column cannot be distinguished from a widespread epidemic due to a malfunction of the head water treatment plant, when diseases appear simultaneously in many areas of the city. The degree of intensity of the epidemic process, and, consequently, the number of cases in both cases is far from being the same.
Seasonal epidemics are characterized by an annual increase in the level of diseases in certain months of the year to a maximum, followed by a more or less slow decrease to the level observed in the off-season period. The frequency of seasonal epidemics is associated with biological, climatic and social factors that determine the activation of infection transmission factors, possibly with an increase in the susceptibility to infection of the population or its individual age groups, the emergence of conditions for more frequent violations of hygiene requirements and the sanitary regime, especially with an unsatisfactory sanitary culture of significant parts of the population.
Thus, during seasonal epidemics, a periodic increase in the intensity of the epidemic process is observed. The leading causes of seasonal epidemics can be eliminated by targeting transmission factors, population susceptibility, and social order factors.
Epidemics - a high level of the spread of infectious diseases among the population, associated with the action of biological and social factors. Among the latter are wars, famines, natural disasters, leading to a deterioration in the sanitary and economic conditions of work and life of the population, increasing the migration of the population. Under these conditions, infectious diseases can spread over vast areas and appear where before they were few or not observed at all. Along with these, local epidemics can also be observed, usually associated with emergency causes (accidents in the sewer and water supply networks, pollution of open reservoirs with fecal effluents that serve as sources of drinking water supply, discharge of undisinfected wastewater from infectious diseases hospitals into public reservoirs, the introduction of especially dangerous infections, etc.). d.). Local epidemics, under appropriate conditions, can spread far beyond the area of original appearance.
The high degree of intensity of the epidemic process during epidemics is determined by the multiplicity of sources of infection, the high susceptibility to infection of the population, the lack of reliable means of specific prevention, the increased likelihood of encountering an infection when traveling in transport, in public premises, and depends on the nature of the leading factors of infection transmission.
A pandemic is characterized by a wide spread of an infectious disease, covering the territory of the entire country, neighboring states, and sometimes many countries of the world. The most famous is the Spanish flu pandemic, which struck most of the countries of the world in 1918-1920, the pandemic of relapsing fever and typhus in our country in the same years. Can be considered a pandemic and the worldwide spread of polio after the Second World War.
Pandemic spread is characteristic of infections to which the susceptibility of the population is extremely high, mainly with a short incubation period and airborne transmission mechanism, especially infections that do not leave strong post-infection immunity. A typical example of such an infection is influenza, whose pandemics recur periodically.
Observing for centuries a bewildering variety of deadly fevers, medical scientists have tried to connect the typical patterns of contagious diseases with specific causes, in order to identify and classify diseases on this basis, and then develop specific methods of counteracting them. Considering the evolution of our knowledge of some of the major epidemic diseases, we can trace the formation of the modern concept of the epidemic.
Plague. In the Middle Ages, the plague epidemics were so devastating that the name of this particular disease, in a figurative sense, became synonymous with all sorts of misfortunes. Plague pandemics following one after another in the 14th century. killed a quarter of the then population of Europe. In vain was the quarantine isolation of travelers and arriving ships.
Plague is now known to be a disease of wild rodents, particularly rats, that is transmitted by the Xenopsyllacheopis flea. These fleas infect people living in close proximity to infected rats, a reservoir of infection. With bubonic plague, human-to-human transmission begins only with the development of a highly contagious pulmonary form of the disease in the patient.
At the end of the 17th century the plague disappeared from Europe. The reasons for this are still unknown. It is assumed that with a change in housing conditions in Europe, the population began to live further from the reservoirs of infection. Due to the lack of wood, houses began to be built of brick and stone, which, to a lesser extent than old-style wooden buildings, is suitable for rats to live.
Cholera. In the 19th century cholera pandemics occurred in most countries of the world. In a classic study by the London physician J. Snow, the water route of infection transmission during the cholera epidemic of 1853–1854 was correctly identified. He compared the number of cases of cholera in two neighboring districts of the city, which had different sources of water supply, one of which was contaminated with sewage. Thirty years later, the German microbiologist R. Koch, using microscopy and bacterial cultivation to identify the causative agent of cholera in Egypt and India, discovered the "cholera comma", later called vibrio cholerae (Vibriocholerae).
Typhus. The disease is associated with unsanitary conditions of existence, usually during the war. It is also known as camp, prison or ship fever. When in 1909 the French microbiologist Ch. Nicol showed that typhus is transmitted from person to person by body lice, its connection with overcrowding and poverty became clear. Knowing the route of transmission allows health workers to stop the spread of epidemic (lice) typhus by spraying insecticidal powder on the clothes and bodies of those at risk of infection.
Smallpox. Modern vaccination as a method of preventing infectious diseases was developed on the basis of the early successes achieved by medicine in the fight against smallpox by immunization (inoculation) of susceptible individuals. To vaccinate, liquid from the smallpox vesicle of a patient with an active infection was transferred to a scratch on the skin of the shoulder or hand of the person being immunized. In case of luck, a mild illness arose, leaving lifelong immunity after recovery. Sometimes immunization caused the development of a typical disease, but the number of such cases was so small that the risk of vaccination complications remained quite acceptable.
In Europe, immunization began to be used from 1721, but long before that it was used in China and Persia. It was thanks to her that by 1770 smallpox had ceased to occur in the wealthy segments of the population.
The merit of further improvement of smallpox immunization belongs to the rural doctor from Gloucestershire (England) E. Jenner, who drew attention to the fact that people who had mild cowpox do not get smallpox, and suggested that cowpox creates immunity to human smallpox.
At the beginning of the 20th century smallpox vaccine has become readily available throughout the world due to its mass production and cold storage. The last chapter in the history of smallpox was marked by a mass vaccination campaign carried out in all countries by the World Health Organization.
Yellow fever. In the 18-19 centuries. among the epidemic diseases of the Western Hemisphere, yellow fever occupied a prominent place in the United States, as well as in the countries of Central America and the Caribbean. Doctors, who assumed that the disease was transmitted from person to person, demanded the isolation of the sick to fight the epidemic. Those who linked the origin of the disease with atmospheric pollution insisted on sanitary measures.
In the last quarter of the 19th century yellow fever was associated with mosquito bites. In 1881, the Cuban physician K. Finlay suggested that Aëdesaegypti mosquitoes served as carriers of the disease. Evidence of this was presented in 1900 by the commission on yellow fever that worked in Havana and was headed by W. Reid (USA).
The implementation of the mosquito control program over the next few years contributed not only to a significant reduction in the incidence in Havana, but also to the completion of the construction of the Panama Canal, which almost stopped due to yellow fever and malaria. In 1937, M. Theiler, a doctor from the Republic of South Africa, developed an effective vaccine against yellow fever, more than 28 million doses of which were produced by the Rockefeller Foundation from 1940 to 1947 for tropical countries.
Polio. Paralytic poliomyelitis (infantile paralysis) as an epidemic disease appeared at the turn of the 19th and 20th centuries. Strikingly, in underdeveloped countries with poor, unsanitary living conditions, the incidence of polio has remained low. At the same time, in highly developed countries, on the contrary, epidemics of this disease began to occur with increasing frequency and severity.
The key to understanding the epidemic process in poliomyelitis was the concept of asymptomatic carriage of the pathogen. This type of latent infection occurs when a person, having become infected with a virus, in the absence of any symptoms of the disease, acquires immunity. Carriers, while remaining healthy themselves, can shed the virus, infecting others. It has been found that in conditions of poverty and crowded living conditions, the likelihood of exposure to the virus increases dramatically, as a result of which children become infected with polio very early, but the disease is quite rare. The epidemic process proceeds like an endemic, secretly immunizing the population, so that only isolated cases of infantile paralysis occur. In countries with a high standard of living, such as North America and Northern Europe, there was a marked rise in the incidence of paralytic poliomyelitis from the 1900s to the 1950s.
The polio virus was isolated by K. Landsteiner and G. Popper already in 1909, but methods for preventing the disease were found only much later. Three serotypes (i.e., the type present in the blood serum) of polioviruses have been identified, and strains of each of them, as it turned out in 1951, were able to multiply in tissue culture. Two years later, J. Salk announced his virus inactivation method, which made it possible to prepare an immunogenic and safe vaccine. Salk's long-awaited inactivated vaccine has been available for mass use since 1955.
The polio epidemic in the United States has stopped. Since 1961, a live attenuated vaccine developed by A. Seibin has been used for mass immunization against poliomyelitis.
AIDS. In 1981, when acquired immunodeficiency syndrome (AIDS) was first described as a specific clinical form, its causative agent was not yet known. The new disease was initially recognized only as a syndrome, i.e. a combination of characteristic pathological symptoms. Two years later, it was reported that the basis of the disease is the suppression of the body's immune system by a retrovirus, which was called the human immunodeficiency virus (HIV). In patients, there is an increased susceptibility to a variety of infectious pathogens, which manifests itself clinically only in the late stages of HIV infection, but at first for a very long time, up to 10 years, the disease may be in the incubation period.
Homosexual men were the first to become ill, then there were reports of transmission of the infection through the transfusion of blood and its components. Subsequently, the spread of HIV infection has been identified among injecting drug users and their sexual partners. In Africa and Asia, AIDS is transmitted predominantly through sexual contact. Currently, the disease is spreading around the world, acquiring the character of an epidemic.
Ebola fever. Ebola virus as the causative agent of African hemorrhagic fever was first identified in 1976 during an epidemic in southern Sudan and northern Zaire. The disease is accompanied by high fever and heavy bleeding, mortality in Africa exceeds 50%. The virus is transmitted from person to person through direct contact with infected blood or other bodily secretions. Medical personnel are often infected, to a lesser extent, household contacts contribute to the spread of infection. The reservoir of infection is still unknown, however, it is possible that these are monkeys, therefore strict quarantine measures have been introduced to exclude the import of infected animals.
