10 dangerous viruses. Viruses: types of viruses, treatment, causes, symptoms, signs, diagnosis, prevention
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Incredible facts
Modern medicine has done a lot to eradicate and cure diseases, but unfortunately, there are still many horrific diseases for which there is no cure.
1. Ebola hemorrhagic fever
Ebola is a virus of the filovirus family that causes severe and often fatal viral hemorrhagic fever. Outbreaks of this disease have been observed in primates such as gorillas and chimpanzees and in humans. The disease is characterized by high fever, rash, and excessive bleeding. In humans, the fatality rate is 50 to 90 percent.
The name of the virus comes from the Ebola River in the northern Congo Basin of central Africa, where it first appeared in 1976. That year, outbreaks in Zaire and Sudan led to hundreds of deaths. Ebola virus closely related to Marburg virus, which was discovered in 1967, and both of these viruses are the only members of the filoviruses that cause epidemics in humans.
The hemorrhagic virus spreads through bodily fluids and, just as patients often vomit blood, caregivers often contract the disease.
2. Poliomyelitis
Poliomyelitis or spinal paralysis is an acute viral infectious disease of the nervous system that begins with general symptoms such as high fever, headache, nausea, fatigue, pain and muscle spasms, sometimes followed by more severe and permanent muscle paralysis one or more limbs, throat or chest. More than half of all polio cases occur in children under 5 years of age. The paralysis that is so often associated with the disease actually affects less than one percent of people infected with the polio virus.
Only 5 to 10 percent of infected people show the above-mentioned common symptoms, and more than 90 percent of people show no signs of illness. For those who have become infected poliovirus, there is no treatment. Since the mid-20th century, hundreds of thousands of children have suffered from this disease every year. Since the 1960s, thanks to the widespread distribution of the polio vaccine, polio has been eliminated in most countries of the world and is now endemic only in a few countries in Africa and South Asia. Every year, about 1,000-2,000 children are left paralyzed by polio.
3. Lupus erythematosus
Lupus erythematosus is an autoimmune disease that leads to chronic inflammation in different parts of the body. There are three main forms of lupus: discoid lupus erythematosus, systemic lupus erythematosus and drug-induced lupus.
Discoid lupus affects only the skin and usually does not involve internal organs. It is characterized by a rash or various patches of redness covered in grayish-brown scales that may appear on the face, neck, and scalp. In about 10 percent of cases in people with discoid lupus, the disease will develop into the more severe systemic form of lupus.
Systemic lupus erythematosus is the most common form of this disease. She can affect almost any organ or body structure, especially the skin, kidneys, joints, heart, gastrointestinal tract, brain and serous membranes.
And while systemic lupus can affect any area of the body, most people experience symptoms in only a few organs. The skin rash may resemble that found in discoid lupus. It is also known that rarely do two people have the same symptoms. This disease is very varied in nature and is marked by periods when the disease becomes active and periods when symptoms are not so obvious.
4. Flu
Influenza is an acute viral infection of the upper and lower respiratory tract, which is characterized by high fever, chills, a general feeling of weakness, muscle pain, and various types of soreness in the head and abdomen.
Influenza is caused by several strains of the family of viruses Ortomyxoviridae, which are divided into types A, B and C. The three main types tend to cause similar symptoms, although they are not antigenically related. So, if you are infected with one type, it does not provide immunity against other types. Type A viruses lead to large epidemics of influenza, and type B causes small localized outbreaks, while type C viruses generally do not cause illness in humans. Between periods of pandemic, viruses undergo constant rapid evolution(a process called antigenic variation) in response to immune onslaught in humans.
Periodically, influenza viruses undergo major evolutionary changes due to the acquisition of new genome segments from another influenza virus, in fact becoming a new subtype from which there is no immunity.
5. Croitfeldt-Jakob disease
Croitfeldt-Jakob disease is a rare fatal degenerative disease of the central nervous system. It is found all over the world and appears with probability one in a million, with slightly higher incidence rates among certain populations, such as Libyan Jews.
The disease most often occurs among adults aged 40 to 70 years, although there have been cases among younger people. Both men and women suffer from it equally.
The onset of the disease is usually characterized by vague psychiatric and behavioral changes, followed by progressive dementia accompanied by visual impairment and involuntary movements. There is no cure for the disease and it is usually is fatal within a year from the onset of symptoms.
The disease was first described in 1920 by a German neurologist Hanz Gerhard Kreutfeld And Alphonse Jacob. Croitfeldt-Jakob disease is similar to other neurodegenerative diseases such as kuru, which occurs in humans, and scabies, which occurs in sheep. All three diseases are types of transmitted spongiform encephalopathy due to the characteristic spongy pattern of neural destruction in which the brain tissue appears to be filled with holes.
6. Diabetes
Diabetes mellitus is a disorder of carbohydrate metabolism, characterized by an impairment of the body's ability to produce or respond to insulin, and thereby maintain the desired blood sugar level.
There are two main forms of diabetes. Diabetes mellitus type 1, formerly called insulin-dependent diabetes and juvenile diabetes, and it usually begins in childhood. This is an autoimmune disease in which the immune system of a person with diabetes produces antibodies that destroy the beta cells that produce insulin. Since the body can no longer produce insulin, daily injections of the hormone are required.
Diabetes mellitus type 2 or non-insulin-dependent diabetes usually appears after age 40, and becomes more common as age increases. It occurs due to sluggish insulin secretion from the pancreas or decreased response in the target cells that secrete insulin. He associated with heredity and obesity, especially upper body obesity. People with type 2 diabetes can control their blood sugar levels through diet and exercise, as well as insulin injections and other medications.
7. AIDS (HIV)
AIDS, or acquired immunodeficiency syndrome, is a transmitted disease of the immune system that is caused by HIV (immunodeficiency virus). HIV attacks slowly destroying the immune system, the body's defense system against infections, which makes a person susceptible to various infections and certain malignancies, which ultimately leads to death. AIDS is the final stage of HIV infection, during which fatal infections and tumors occur.
HIV/AIDS spread in the 1980s, especially in Africa, where it is believed to have originated. Several factors contributed to the spread, including increased urbanization and long-distance travel to Africa, international travel, changing sexual morals, and intravenous drug use.
According to the 2006 UN report on HIV/AIDS, about 39.5 million people are living with HIV, about 5 million people become infected each year, and about 3 million die from AIDS each year.
8. Asthma
Asthma is a chronic airway disease in which the inflamed airways tend to constrict, causing episodes of suffocation, difficulty breathing, coughing and chest tightness that range in severity from mild to life-threatening. Inflamed airways become hypersensitive to a variety of stimuli, including dust mites, animal dander, pollen, air pollution, cigarette smoke, medications, weather conditions and exercise. Wherein stress can make symptoms worse.
Asthmatic episodes may begin suddenly or may take several days to develop. Although the first episode can occur at any age, half of cases occur in children under 10 years of age, and it occurs more often in boys than in girls. Among adults, the incidence rate is approximately the same in women and men. When asthma develops in childhood, it is often associated with inherited susceptibility to allergens, such as pollen, dust mites, animal dander, which cause an allergic reaction. In adults, asthma can also develop in response to allergens, but viral infections, aspirin and exercise can also trigger the disease. Polyps and sinusitis are also common in adults with asthma.
9. Cancer
Cancer refers to a group of more than 100 different diseases characterized by the uncontrolled growth of abnormal cells in the body. Cancer affects one in three people born in developed countries and is one of the leading causes of illness and death worldwide. Although cancer has been known since ancient times, significant improvements in cancer treatment were made in the mid-20th century, mainly through timely and accurate diagnosis, surgery, radiation therapy and chemotherapy drugs.
Such advances have led to a decline in cancer mortality and have also led to optimism in laboratory research in elucidating the causes and mechanisms of the disease.
Thanks to ongoing advances in cell biology, genetics and biotechnology, researchers now have fundamental knowledge of what happens in cancer cells and in cancer patients, facilitating further progress in preventing, diagnosing and treating the disease.
10. Cold
The common cold is an acute viral illness that begins in the upper respiratory tract, sometimes spreads to the lower respiratory tract, and can cause secondary infections in the eyes or middle ear. Cold can cause more than 100 viruses, including parainfluenza virus, influenza virus, respiratory syncytial virus, reoviruses and others. However, rhinoviruses are considered the most common cause.
The term cold is associated with the feeling of cold or exposure to a cold environment. It was originally thought that colds were caused by hypothermia, but research has shown that this is not the case. They catch a cold in contact with infected people, not from the cold, cold wet feet or drafts.
People can carry the virus and not experience symptoms. The incubation period is usually short, ranging from one to four days. Viruses begin to spread from an infected person before symptoms appear and spread peaks during the symptomatic phase.
There is such a variety of viruses that cause colds that It is practically impossible for a person to develop immunity to colds. To date, there are no medications that can significantly shorten the duration of the disease, and most treatment is aimed at mitigating symptoms.
A mild cough is often where diseases, outbreaks of epidemics and even pandemics begin, which can spread across entire continents. However, modern medicine and hygiene rules have given us the opportunity to repel the most destructive infections.
Today it seems that we have the epidemic situation under control. Indeed, humanity has coped, for example, with smallpox, eradicated the plague and other deadly dangers. However, most infections still remain with us, periodically manifesting themselves in the poorest (and therefore vulnerable) countries.
What infectious diseases have claimed the greatest number of lives on our planet? From which infections has humanity suffered more than from all the wars that have ever happened on Earth?
And another, most important question: what infections can become potential killers of humanity? What infectious diseases currently claim millions of lives every year? We present to your attention a list of the 27 most famous and terrible infectious diseases.
Black pox
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In one hospital in Dhaka, the capital of Bangladesh, the mortality rate was 46 percent. In 1959, there was a small outbreak of smallpox in Moscow, where the infection came from India (it was “brought” by a citizen of the USSR who visited India). Thanks to the efforts of Soviet doctors, the disease was stopped, although three people still died.
Some scientists believe that smallpox, which leaves characteristic scars on human skin, began its destructive path from Egypt three thousand years ago. The blackpox virus, which is the cause of smallpox, killed at least a third of those infected. The rest were left disfigured.
The World Health Organization (WHO) announced in 1980 that the disease had been completely eradicated thanks to an unprecedented vaccination campaign that took decades. The latest strains of the virus are stored in special centers under certain conditions in Russia and the United States of America.
Plague
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There are three types of plague, but the best known form is bubonic plague, which causes painful inflammation of the lymph nodes, called buboes. Plague still occurs in representatives of the animal world throughout the planet, but especially in the western United States and Africa.
In September 2016, WHO reported 783 cases of plague worldwide, 126 of which were fatal. In Russia, the bubonic plague manifested itself quite recently, in Altai, where a 10-year-old boy became infected with it through contact with a sick animal. In total, according to historians, in our era the plague took the lives of about 150 million people (mainly during major epidemics).
Malaria
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Rabies used to be called hydrophobia, since the sound of pouring water causes a spasm, it is impossible to take a sip. To date, medicine knows of fewer than ten cases of survival after a person infected with rabies exhibited the symptoms described above.
Regardless, there is a rabies vaccine that has been shown to be most effective as a preventative measure and also as a method of treating an infected person before he or she develops the symptoms discussed above.
Rabies has been known to mankind since time immemorial. The specificity of infection (through animal saliva) saved our species from massive pandemics of this infection. However, even in our time, there are reports of surges of this infection in a number of backward countries or even tribes. Usually the cause is contact with one or another infected animal.
Pneumonia
While not usually as awe-inspiring as rabies or bubonic plague, this lung infection is a fatal disease. Pneumonia is especially dangerous for children under five years of age and elderly people over 65 years of age. Many people underestimate the danger of pneumonia. If powerful outbreaks of plague have sunk into oblivion, then, according to WHO, almost a million children around the world died from lung disease in 2015. In general, this disease claims seven million lives a year, with almost half a billion people affected.
Rotavirus infection
Rotavirus infection, caused by rotaviruses, is the most common cause of acute gastroenteritis in children, accompanied by acute diarrhea. This disease, which causes inflammation of the intestines and stomach, is also fatal. According to WHO, in 2013, rotavirus killed 215 thousand children under the age of five worldwide. About 22 percent of deaths occurred in India. This viral infection leads to dehydration of the body resulting in severe diarrhea and vomiting. In total, there are up to 25 million cases of this infection per year in the world; 660 to 900 thousand die.
Causative agents of infectious diseases in humans
Ebola
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Some Ebola patients experienced bleeding from the mouth and nose during the later stages of the disease, a condition known as hemorrhagic syndrome. The most recent Ebola outbreak occurred in South Africa in 2014; This is by far the largest outbreak in history.
By April 2016, 28,652 cases were known. Of these, almost 11,300 people died. Ebola is transmitted from person to person through body fluids. There is also a risk of contracting the virus through contact with the blood of an infected person, saliva, sweat (or by touching, for example, clothing or bedding that has absorbed an infected substance).
Creutzfeldt-Jakob disease
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These infections tend to be transmitted from animals (cattle) to people. The word “spongy” in the name appeared because infections lead to the degradation of brain tissue and the appearance of characteristic holes in the cerebral cortex, which, when enlarged, resemble a sponge.
A person can become infected with this infection, for example, by eating beef contaminated with bovine spongiform encephalopathy. Essentially, this is the same disease, only in animals.
As mentioned above, this is a rare infection. Its geography is not particularly tied to backward countries, as is the case with, say, malaria. For example, between 1996 and March 2011, 225 cases of the disease were recorded in the UK. Cases of infection have also been reported in France.
It is noteworthy that until 1996, scientists had no idea that a person could acquire spongiform encephalopathy by eating meat contaminated with spongiform encephalopathy. Before this, it was known only about the hereditary nature of the disease, and also that the disease could be introduced into the body of the person being operated on during surgery on the brain or eyes.
Despite its non-prevalence, this infection is extremely merciless. It is known that in the case of mild forms of mad cow disease, the survival rate of patients is 85 percent. If we are talking about a severe form of this disease, then the death of the patient is inevitable.
Marburg hemorrhagic fever
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The fever itself is transmitted from person to person through body fluids (like Ebola). In general, the Marburg virus has a lot in common with Ebolavirus, which is not surprising, since the latter also belongs to the filovirus family.
Humans can become infected with this disease from bats of the fruit bat family. Some of those infected exhibit acute hemorrhagic fever. According to various sources, the mortality rate for this disease ranges from 60 to 90 percent.
This virus was first identified in Germany in 1967. Then, employees of a scientific laboratory who conducted experiments with monkeys from Uganda became infected with Marburg disease. As it turned out, monkeys, just like people, are susceptible to this infection.
But in bats, which are carriers of the virus, it does not cause the corresponding disease (as is the case with Ebola). Despite appropriate treatment, fever leads to serious complications, which may include long-term mental disorders.
Middle East respiratory syndrome
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This disease first became known in 2012, after cases of infection in Saudi Arabia. Three years later, WHO published information about 1,154 cases of infection in 23 countries, of which 431 cases were fatal.
Some people who become infected with this infection may not show any symptoms. But most often, those infected develop a fever, cough, and shortness of breath. In more severe cases, organs (for example, kidneys) fail to function and breathing stops.
An infectious disease that threatens billions of people
Dengue fever
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It is noteworthy that without the complicity of these two species, a healthy person cannot catch dengue fever from an infected person. The symptoms are initially almost the same as for the flu: the patient has a fever, he coughs, the temperature rises, and chills appear.
At more serious stages, the symptoms become much more numerous. Sometimes the virus leads to a potentially fatal condition known as severe dengue. We are talking about dengue hemorrhagic fever, which causes stomach pain, vomiting, bleeding and difficulty breathing.
According to WHO, an average of 400 million people suffer from dengue fever each year. Some scientists who are seriously studying the ways of dengue spread claim that almost 4 billion people in 128 countries of the world are at risk of spreading this fever.
Yellow fever
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This fever got its name due to one of the symptoms (recorded, by the way, in a small percentage of people who get sick) - the appearance of yellowness of the skin and eyes. However, the vast majority of those who have encountered this disease have never encountered such a symptom.
The color of the skin and whites of the eyes changed in those people who had a second, more severe phase of fever, which has a destructive effect on human organs, including the liver and kidneys. According to the WHO, half of patients in the second phase of yellow fever (hemorrhagic fever) died within seven to ten days.
The mortality rate for this disease is quite high: for every two hundred thousand infected, there are 30 thousand deaths. Almost 90% are in Africa. Fortunately for many people in the 47 countries at risk (including Central and South America), there is a highly effective vaccine against the disease.
This was not the case at all in the 17th century, when the yellow fever virus, which first appeared in North America and then in Europe, caused severe epidemic outbreaks of the disease, sending many thousands of people to the next world.
Hantavirus pulmonary syndrome
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The world first learned about one of these viruses, most often causing hantavirus pulmonary syndrome (Sin Nombre Virus), after its discovery in the United States in 1993. Then, several young people died mysteriously in the southwestern region of the country, called the “four corners.”
24 people were taken to the hospital, half of whom subsequently died. Then the world first learned about a new virus, which was later dubbed the Sin Nombre virus (actually, “unnamed virus” in Spanish), leading to a severe respiratory infection.
Outside the United States—in Asia, Europe, and parts of Central and South America—hantaviruses also cause a serious illness known as hemorrhagic fever with renal syndrome.
The initial symptoms of this disease are similar to those of hantavirus pulmonary syndrome (fever, vomiting, nausea), but it can cause bleeding and kidney failure. The disease is extremely dangerous, since diseases from hantaviruses are tens of times more common than rabies, for example.
Spread of infectious diseases
anthrax
(anthrax) belongs to the category of especially dangerous infectious diseases. This infection is caused by anthrax, a type of bacteria called Bacillus anthracis that lives in soil. Initially, wild and domestic animals (cattle, sheep, goats, etc.) are infected. Humans usually become infected while caring for animals or from animal products. Bacterial spores can penetrate a person's skin, but sometimes they can be inhaled (for example, when working with animal skins or hair). The pulmonary form of the disease is much more deadly - death occurs in 92 percent of cases of infection.
Anthrax has been known about for a long time. A similar disease was mentioned in Chinese manuscripts about five thousand years ago. The bacterium Bacillus anthracis is believed to have wiped out entire animal species. It is no coincidence that anthrax spores are considered a bacteriological weapon intended for the mass destruction of the enemy.
Whooping cough
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However, the fungal type of meningitis is not contagious, although it can cause an outbreak of this disease, as happened, for example, in the United States in 2012, when hundreds of patients were infected through injections of a drug containing fungal spores. Several dozen people died.
Meningococcal meningitis is caused by the bacterium Neisseria meningitidis, which causes flu-like symptoms - nasal discharge, nausea, sensitivity to light, and confusion. A fatal outcome remains possible, although the situation has changed dramatically over a hundred years: then the mortality rate could exceed 90 percent.
Syphilis
is an infectious disease of a chronic nature. This is a sexually transmitted disease, that is, the main route of infection is sexual contact with an infected person. However, there are many cases of infection through blood (among drug addicts; through the use of the same toothbrush, where microscopic particles of blood from the patient’s gums remain, and so on). Syphilis can now be cured quite simply, but it is a very insidious disease. If the infection is started, it leads to severe complications. At the first stage of the disease, syphilitic ulcers appear on the patient's genitals and anus.
They are usually very small, although painful, and go away on their own. A sick person can immediately forget about temporary inconveniences, attributing them to temporary pimples that popped up for some reason not worth attention.
At the second stage of this disease, syphilis begins to express itself clearly - a rash begins to appear in one or different parts of the body. However, even in this case, the rash may not be very bright and may not be accompanied by itching. The patient may not even pay attention to these rednesses.
In other cases, the rash may be accompanied by fever, swollen lymph nodes, and muscle pain. And if syphilis was not treated during the development of the first and second stages, subsequent problems for the patient will be simply catastrophic.
It also happens that syphilis does not reach the late stage for a very long time. According to some reports, this can last from 10 to 30 years. However, at a later stage, the patient loses the ability to coordinate muscle contractions, paralysis, rigor, bleeding occurs, and dementia is noted. If internal organs are damaged, the patient may die.
According to data for 2016, up to three hundred thousand patients with syphilis are registered in Russia annually. Currently, the disease is only fatal if left untreated (in about a third of patients with advanced disease). During the Renaissance, syphilis destroyed tens of millions of people, being almost the main cause of death in some periods of history.
Infectious diseases causing deformities
Leprosy
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Leprosy affects the affected person's skin, peripheral nerves, upper respiratory tract and eyes. If left untreated, it leads to muscle atrophy, physical deformities and permanent damage to the nervous system.
Although people at one time tried to protect themselves from contact with people with leprosy, this infectious disease is not so contagious. The infection is spread through airborne droplets when an infectious person sneezes or coughs.
If you simply touch someone with leprosy, there is no particular risk of becoming infected. Moreover, according to WHO, the immune system of a healthy person is usually able to resist this infection when the bacteria gets inside. However, the most vulnerable category is children.
According to WHO, in 2017, more than two hundred thousand new cases of leprosy were registered in the world. In approximately 40 percent of cases, patients face disability. If there is no proper treatment, a person is doomed within 5-10 years.
Measles
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The infection leads to the appearance of a characteristic rash on the skin, which is accompanied by general intoxication of the body. Other symptoms of this dangerous disease are not much different from the symptoms of a common cold.
Measles is such a contagious disease that simply being indoors with an infected person can be dangerous. According to WHO, 134,200 people died from measles in 2016. Before the spread of vaccination (that is, in 1980), this disease claimed the lives of 2.6 million people.
Fortunately, vaccination has proven to be extremely successful in combating this viral infection. It is known that out of every thousand people vaccinated against measles, 997 have never encountered this disease.
Atypical pneumonia
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Bats help spread this disease (as in the case of the Ebola virus, Marburg fever and Middle East respiratory syndrome). In this case, the distributors are the so-called horseshoe bats.
The virus began its movement from China, but quickly spread to other countries and continents due to the fact that the Chinese authorities initially tried to hide information about the outbreak of this disease. The SARS case showed humanity how important it is to act together when it comes to such formidable opponents as viral and bacterial infections.
Staphylococcal infection
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The main problem is that this Staphylococcus aureus (as it is called for simplicity) is able to resist most antibiotics. The history of the “fight” of staphylococcus with antibiotics began back in 1940, when doctors began treating staphylococcal infections with penicillin.
An overdose of the drug (or its misuse) led to the fact that microbes developed resistance to penicillin over a period of ten years, which forced scientists to try a new way to combat staphylococci - using an antibiotic called methicillin.
However, staphylococci have also demonstrated the ability to develop resistance to this drug. Today, this microbe is able to resist the effects of many antibiotics of the penicillin group, such as amoxicillin, oxacillin, dicloxacillin and all other beta-lactam antibiotics.
As a result, humanity has received a powerful enemy in the form of a sort of super microbe that causes infections that are difficult to diagnose and disguise themselves as other diseases. They reduce the body's defenses, facilitating the penetration of toxins into the blood and tissues, causing many dangerous pathologies.
Staph skin infections usually start as small red rashes that can develop into pus-filled boils that require surgery. These infections can cause even more serious consequences by affecting the blood, heart, bones and other internal organs of a person. Sometimes they lead to the death of the patient.
Zika virus
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It belongs to the genus of flaviviruses transmitted by the already known genus of biting mosquitoes (Aedes). The disease caused by this virus, called Zika disease, is not particularly dangerous for most people. But today the disease has pandemic status.
According to research, every fifth person infected with the Zika virus eventually develops the disease of the same name. However, the virus threatens serious complications for the human body developing in the womb and for newborn children.
Those infected experience a fever, a rash, joint pain, and conjunctivitis, but these symptoms are mild and last only a few days. However, the virus causes miscarriages in pregnant women and leads to congenital malformations (for example, microcephaly).
So what is the deadliest virus on Earth? You'd think this would be a simple enough question to answer, but it turns out there's more than one way to determine how lethal a virus is. For example, is it a virus that kills the most people (overall mortality rate) or is it a disease that has a high mortality rate, i.e. kills the most number of infected people. For most of us it will be the disease with the highest mortality rate, it is definitely a death sentence if you ever contract it.
Ironically, it is a series of diseases that have a reassuringly low mortality rate that actually kill millions of people. There is a reason for this - they are viruses that cause the most dangerous diseases, usually killing themselves by killing their hosts faster than they can spread. Two particularly good examples of this phenomenon are the Ebola virus, which has a 90% case fatality rate and has killed around 30,000 people to date, and the Spanish flu pandemic, which has killed an estimated 100 million people despite the fact that it has a fatality rate of less than 3%.
Apart from the two measures of overall mortality rate and death rate mentioned above, there is also a historical dimension: which virus has killed the most people throughout history?
Considering these various criteria to determine which virus is the most deadly, we will take all these indicators into account to not only compile the TOP 10 viruses, but also provide some individual statistics at the end of the article.
10. Dengue fever
Photo. Mosquito
Dengue fever is a mosquito-borne infection that was first described nearly 2,000 years ago in China. After gradually spreading to other countries with yellow fever mosquitoes (lat. Aedes aegypti), the spectrum of diseases expanded significantly in the 18th century. This was due to the slave trade, as well as human activity during World War II, when the spread accelerated, especially of more dangerous forms of disease.
In recent years, globalization has had its impact on dengue fever rates, which have increased 30 times since the 1960s.
As with many of these diseases, the vast majority of people either had no symptoms or experienced fairly mild symptoms not typical of a fever. Dengue fever is sometimes referred to as “breakbone fever,” which describes the severe pain that can be felt in the muscles and joints.
For those unlucky enough, the disease can develop into "severe dengue" with the risk of potential death as a result of dengue hemorrhagic fever and dengue shock syndrome. This occurs in less than 5% of cases, the main reason for this is increased permeability of blood vessels. This can lead to vomiting blood, organ damage, and shock.
Today, dengue fever infects up to 500 million people each year in 110 countries where dengue fever is endemic, resulting in approximately 20,000 deaths. The grim reality is that these numbers will continue to rise.
9. Smallpox
Photo. Smallpox patient
Smallpox has been eradicated, right? WHO claims that it has not happened since 1979, however, the USA and the former USSR conducted scientific research on samples of the virus. According to some rumors after the collapse of the Soviet Union, some of these samples went missing. Even if the variola virus became extinct, it could conceivably be re-engineered from the digital viral genome and inserted into the poxvirus shell.
The good news is that all targets of smallpox are now extinct in the wild. Although historically this has led to devastating effects. Smallpox appeared around 10,000 BC, at that time it led to mass death. Smallpox is contagious and, of course, in those early days the mortality rate reached up to 90%.
The most terrible period for people was when smallpox was brought to the New World by European explorers in the 18th century. Whether it was by accident or not, it is estimated that around half of Australia's Aboriginal population was killed by smallpox in the early years of British colonization. The disease also had a negative impact on the indigenous populations of the Americas.
Despite the fact that Edward Jenner developed the smallpox vaccine in 1796, an estimated 300-500 million people died due to it in the 1800s.
What's particularly shocking about smallpox is that the body becomes covered in fluid-filled blisters. It can occur in the mouth and throat and in some cases smallpox has led to complications such as blindness. The mortality rate from this disease largely depends on the course in which the disease develops; if it is malignant and hemorrhagic smallpox, it will invariably lead to death.
8. Measles
Photo. Child with measles
Most people in developed countries do not consider measles to be even remotely dangerous. We are accustomed to the fact that about 90% of all children will have had measles by the time they reach 12 years of age. Nowadays, with routine vaccination carried out in many countries, incidence rates have decreased significantly.
But what may shock you is that between 1855 and 2005, measles claimed 200 million lives worldwide. Even in the 1990s, measles killed over 500,000 people. Even today, with the advent of cheap and accessible vaccines, measles is a leading cause of death among young children, killing more than 100,000 people each year.
Measles has caused the greatest devastation in communities that had not previously been exposed to it. In the 16th century, measles was brought to Central America by Europeans. In particular, Honduras lost half of its population during a measles epidemic in 1531.
In common cases, measles results in fever, cough and rash. However, complications are quite common and this is where the danger lies. In about 30% of cases, symptoms range from relatively mild, such as diarrhea, to pneumonia and inflammation of the brain, all of which can lead to death. Other complications include blindness.
7. Yellow fever
Photo. Memorial in Savannah, Georgia
Another major killer in history is yellow fever. Also known as the "yellow plague" and "vomito negro" (black vomit), this acute hemorrhagic disease has resulted in a number of serious outbreaks over the centuries.
Most people recover completely from yellow fever, but about 15% of cases progress to a second, more serious stage of the disease. In these cases, there may be bleeding from the mouth, nose, eyes or stomach. About 50% of patients who enter this toxic phase die within 7-10 days. Although the overall mortality rate reaches 3%, during epidemics it reached 50%.
Like most similar viral infections, yellow fever originated somewhere in Africa. During the early colonial years, it was noted that outbreaks in the village among the natives did not result in serious complications, more like flu-like symptoms, while most European colonists died. This difference in disease severity is thought to be caused by long-term exposure to low doses during childhood, which results in some immunity.
It could be argued that there is a certain schadenfreude in the fact that slavery and the exploitation of Africa led to epidemics in Europe and North America in the 18th and 19th centuries. Probably the most famous of these was the 1792 outbreak in Philadelphia, then the capital of the United States. President George Washington was reported to have fled the city, while 10% of those who remained died.
Yellow fever swept across America, claiming between 100,000 and 150,000 lives in the 18th and 19th centuries.
Today, despite the existence of an effective vaccine, there are regions where yellow fever affects 200,000 people worldwide each year, claiming 30,000 lives each year.
6. Lassa fever
Photo. Electron micrograph of Lassa virus
You might think of Lassa fever as a “mild variant of Ebola,” but then again it kills as many people every year in West Africa as Ebola did at the height of the 2013-15 epidemic. In addition, the symptoms are easily confused with Ebola; they are both classified as acute viral hemorrhagic fevers. Lassa fever infects virtually every tissue in the human body and outbreaks are usually triggered by the local Mastomys rat.
If you doubt the dangers of Lassa fever, its Biosafety Level 4 (BSL-4) should reassure most of you. This is the highest level of biosafety and is designed to work with pathogens that can cause death and for which there is no vaccine or treatment. To give an overview, MRSA, HIV and hepatitis viruses are classified as Biosafety Level 2.
On average, Lassa fever kills 5,000 people every year. It is estimated that more than 300,000 people are endemicly infected each year throughout West Africa. Although most do not experience any symptoms, those who do have a mortality rate of 15-20%. During epidemics, the mortality rate of Lassa fever reaches 50%. This is not quite similar to the Ebola virus or the Marburg virus, but still the indicators are dangerous.
5. Hepatitis
Photo. Hepatitis C virus
Hepatitis is the name given to a series of viral diseases that attack the liver. There are 5 types of infectious hepatitis, which are designated by letters from A to E (A, B, C, D, E). Of all of them, the most serious are hepatitis B and hepatitis C, which together claim almost a million lives every year. They are often passed from mother to child, but can also be transmitted through blood transfusions, tattoos, dirty syringes and sexual activity.
Hepatitis B reaps the largest number of deaths per year (about 700,000). This is a rather inconspicuous disease that is asymptomatic. Most deaths are the result of a disease that slowly attacks a person's liver over several years, eventually leading to liver cancer or cirrhosis. Although hepatitis B infection in an adult usually results in an acute episode of illness, it ends in full recovery. Children tend to become infected, who are more prone to developing the disease in the long term.
Although the overall death rate from hepatitis C is lower than that of hepatitis B, it still kills approximately 350,000 people each year, mostly in developing countries. Figures show that approximately 200 million people (or 3% of the total population) are living with hepatitis C.
4. Rabies
Photo. Patient in the last stages of rabies
Rabies is one of the deadly diseases belonging to the Lyssavirus genus. This name is derived from Lyssa, the Greek goddess of rage, madness and wrath, the word itself being derived from the Latin "madness". This is one of the most terrible diseases of mankind, which has been known since ancient times and there is every reason for this.
The most well-known form of rabies is referred to as "furious rabies" and affects 80% of those infected. This stage includes the classic symptoms of confusion, psychomotor agitation, paranoia and terror. An infected person may also exhibit hydrophobia (fear of water). In this seemingly strange state, the patient panics when given something to drink. Rabies infects the salivary glands in the back of the mouth, so it can be transmitted by a simple bite. This infection also causes the throat muscles to go into painful spasms, leading to increased salivation.
Rabies is contracted when an infected animal, usually a dog or bat, bites or scratches a person. Although some flu-like symptoms may occur after the bite, the disease is usually asymptomatic during the incubation period. This usually lasts 1-3 months, but it can take years for the infection to travel through the nervous system to the brain.
Rabies is difficult to diagnose and if a suspicious bite is left undetected, neurological symptoms can develop. At this stage it is definitely too late for the patient; rabies has an almost 100% fatality rate, occurring within a few days. In fact, only 6 people have survived rabies, the first being Jeanna Giese in 2005. She was a new approach (Milwaukee protocol) in the fight against this disease, she was put into an induced coma and she survived, almost fully recovered. Despite the success in this case, this method still has approximately an 8% chance of success.
Fortunately, being bitten by an animal infected with rabies is no longer a death sentence. If you receive post-exposure prophylaxis (PEP) treatment for 10 days, you have an almost 100% chance of survival. There is also an equally effective vaccine.
However, rabies still kills nearly 60,000 people every year, mostly in Africa and South Asia. More than one-third of these deaths occur in India, where dogs are still the main culprits. More details about this disease and can be found in our other article.
3. Viral hemorrhagic fevers (Filoviruses)
Photo. 2015 Ebola outbreak
If any disease can cause fear in the 21st century, it is viral hemorrhagic fevers from the filovirus family. These include the Ebola virus and the Marburg virus, for both there is no effective treatment, there is no vaccine and the mortality rate reaches 90%. Having very unpleasant symptoms, these are potentially deadly viruses on Earth.
From a diagnostic point of view, Marburg and Ebola are clinically indistinguishable. The name of this group of viruses serves as a clue to some of the symptoms; it is obvious that these fevers are accompanied by pain throughout the body, joints, muscles, abdominal pain, and headaches. The hemorrhagic aspect is due to the fact that filoviruses interfere with the blood clotting mechanism, thereby causing bleeding from any orifice of the human body. More than likely, death is usually explained by multiple organ failure and necrosis of internal tissues.
Ebola and Marburg typically emerged in isolated villages in central Africa in small outbreaks that quickly wiped themselves out. However, in 2013, the Ebola virus arrived in the West African country of Guinea, where it was not recognized as such until it began to spread rapidly. Over the next 2 years, the Ebola epidemic raged in six countries, infecting 25,000 people, of whom about half died.
The largest outbreak of Marburg virus occurred in 2004 in Angola. Of the 252 infected, 227 died, i.e. 90%. During early epidemics, the death rate in Congo reached 83%.
The Marburg and Ebola viruses are believed to have been transmitted to humans from wild animals. Although the first cases of Marburg virus infection occurred in researchers working with African green monkeys, bats are believed to be the virus's natural host. This is also true of the Ebola virus, which is why bats are considered the main carriers of some of the most feared diseases on Earth.
2. HIV/AIDS
Photo. HIV virions infect cells
Over the past three decades, AIDS has become headline news and is a devastating disease. Tremendous advances in antiretroviral drugs mean that taking the correct medications for HIV infection is not the death sentence it used to be.
This disease is another that originated in central Africa, where it lurked in monkey populations for millions of years until it crossed paths with humans in the mid-20th century. It is not known exactly how this happened, but it is believed that the monkey SIV (simian immunodeficiency virus) transmitted the virus to humans through eating meat, the virus later mutated and we currently know it as HIV.
It is suspected that HIV had been around for some time before it became mainstream news, with the first reported case occurring in the Congo in 1959.
The main reason for not finding a direct cure for HIV is the fact that it is constantly and rapidly changing. It reproduces rapidly (about 10 billion new individual virions per day) and the rate of mutation is very high. Even within a single individual, the genetic diversity of the virus can resemble a phylogenetic tree, with different organs infected by virtually different species.
Today, approximately 40 million people are living with HIV, mostly in sub-Saharan Africa. Unfortunately, only half of infected people have access to the necessary medications, which is why the global AIDS death rate is so high. AIDS is estimated to claim about 2 million lives each year, and the virus has claimed the lives of more than 25 million people over the past 30 years.
1. Flu
Photo. Patients with Spanish flu
Influenza is the most widely known virus and is hardly the most exciting among our list of deadly viruses. Everyone had the flu and for most it didn't end well. However, every year the flu causes a large number of deaths and the most vulnerable groups of the population are the elderly, the very young and the sick. Despite the development of a safe and effective vaccine more than 60 years ago, influenza still kills up to half a million people every year.
But this is only a baseline, and there are occasional devastating epidemics when virulent strains of the virus develop. The 1918 Spanish Flu is a prime example of this. It is believed to have infected almost a third of the world's population and claimed up to 100 million lives. During the epidemic, the mortality rate was 20% compared to the usual seasonal flu of 0.1%. One of the reasons why the Spanish flu was so deadly was because it killed healthy people, a particular strain causing an overreaction of the immune system known as a cytokine storm. Therefore, people with strong immune systems were at greatest risk.
Other diseases don't even come close to these numbers, which is what makes the flu so dangerous. The influenza virus has the ability to frequently combine and mutate to form new strains. Fortunately, the most deadly strains are now different from the most contagious strains. One fear is that the potentially deadly H5N1 strain of bird flu, which cannot be transmitted from person to person, for example, would require a small genetic "event" to create a possible epidemic. Although there have been only just over 600 cases of avian influenza to date, nearly 60% of them have been fatal, making it one of the most dangerous diseases for humans.
There are a myriad of microorganisms in the world, viruses predominate among them. They can survive in the harshest conditions. Viruses have been found in the eternal ice of Antarctica, in the hot sands of the Sahara, and even in the cold vacuum of space. Although not all of them pose a danger, more than 80% of all human diseases are caused by viruses.
Back in the 40s of the last century, humanity knew about 40 diseases provoked by them. Today this figure is more than 500, not counting the fact that new species are discovered every year. People have learned to fight viruses, but knowledge is not always enough - more than 10 of their types remain the most dangerous for humanity. Viruses are causative agents of dangerous human diseases. Let's look at the main ones.
Hantaviruses
The most dangerous type of virus is hantavirus. When contacting small rodents or their waste products, there is a possibility of becoming infected. They can cause many diseases, the most dangerous of which are hemorrhagic fever and hantavirus syndrome. The first disease kills every tenth person, the probability of death after the second is 36%. The largest outbreak occurred during the Korean War. Then more than 3,000 soldiers from different sides of the confrontation felt its effect. There is a strong possibility that the hantavirus caused the extinction of the Aztec civilization 600 years ago.
Ebola virus
What other dangerous viruses exist on Earth? The epidemic created panic in the world community just a year ago. The virus was discovered in 1976, during an epidemic in the Congo. It got its name in honor of the pool in which the outbreak occurred. Ebola disease has many symptoms, making it difficult to diagnose. The most common of them include: increased body temperature, general weakness, vomiting, impaired liver and kidney function, sore throat. In some cases, internal and external bleeding is observed. In 2015, this virus took the lives of more than 12 thousand people.
How dangerous is the influenza virus?
Of course, no one would argue that the dangerous virus is an ordinary flu. More than 10% of the world's population suffers from it every year, making it one of the most common and unexpected.
The main danger to people is not the virus itself, but the complications it can cause (kidney disease, pulmonary and cerebral edema, heart failure). Of the 600 thousand people who died from the flu last year, only 30% of deaths were caused by the virus itself; the rest were the result of complications.
Mutations are another danger of the influenza virus. Due to the constant use of antibiotics, the disease becomes stronger every year. Chicken and swine flu, epidemics of which have broken out over the past 10 years, are yet another confirmation of this. In the worst-case scenario, in a few decades, drugs that can fight influenza will pose an extreme danger to humans.
Rotavirus
The most dangerous type of virus for children is rotavirus. Although the medicine for it is quite effective, about half a million babies die from this disease every year. This disease causes acute diarrhea, the body quickly becomes dehydrated and death occurs. Most of those affected live in underdeveloped countries where it is difficult to obtain a vaccine against this virus.
Deadly Marburg
The Marburg virus was first discovered in the city of the same name in Germany in the late 60s of the last century. It is one of the top ten deadly viruses that can be contracted from animals.
About 30% of diseases with this virus are fatal. In the early stages of this disease, a person suffers from fever, nausea, and muscle pain. In more severe cases - jaundice, pancreatitis, liver failure. The disease is transmitted not only by humans, but also by rodents, as well as some species of monkeys.
Hepatitis in action
What other dangerous viruses are known? There are more than 100 types of them that affect the human liver. The most dangerous of them are hepatitis B and C. It is not for nothing that this virus is nicknamed the “gentle killer”, because it can remain in the human body for many years without causing noticeable symptoms.
Hepatitis most often leads to the death of liver cells, that is, cirrhosis. It is almost impossible to cure the pathology caused by strains B and C of this virus. By the time hepatitis is detected in the human body, the disease, as a rule, is already in a chronic form.
The discoverer of this disease was the Russian biologist Botkin. The strain of hepatitis he found is now called “A”, and the disease itself is treatable.
Smallpox virus
Smallpox is one of the oldest diseases known to mankind. It only affects humans, causing chills, dizziness, headaches and lower back pain. A characteristic sign of smallpox is the appearance of a purulent rash on the body. Over the past century alone, smallpox has killed nearly half a billion people. Enormous amounts of material resources (about $300 million) were used to combat this disease. Yet virologists have achieved success: the last known case of smallpox was recorded forty years ago.
Deadly rabies virus
The rabies virus is the first of this rating, leading to death in 100% of cases. You can become infected with rabies after being bitten by a sick animal. The disease is asymptomatic until the time when it is no longer possible to save the person.
The rabies virus causes severe damage to the nervous system. In the last stages of the disease, a person becomes violent, experiences a constant feeling of fear, and suffers from insomnia. A few days before death, blindness and paralysis occur.
In the entire history of medicine, only 3 people have been saved from rabies.
Lassa virus
What other dangerous diseases are known? The virus caused by this virus is one of the most dangerous diseases in West Africa. It affects the human nervous system, kidneys, lungs, and can cause myocarditis. During the entire period of illness, body temperature does not fall below 39-40 degrees. Many painful purulent ulcers appear on the body.
Lassa virus is transmitted by small rodents. The disease is transmitted by contact. Every year, about 500 thousand people become infected, of which 5-10 thousand die. In severe forms of Lassa fever, the mortality rate can reach 50%.
Human acquired immunodeficiency syndrome
The most dangerous type of virus is HIV. It is considered the most dangerous of those known to man at this time.
Experts have found that the first case of transmission of this virus from a primate to a human occurred in 1926. The first death was recorded in 1959. In the 60s of the last century, symptoms of AIDS were discovered in American prostitutes, but then they did not attach much importance to this. HIV was considered simply a complex form of pneumonia.
HIV was recognized as a separate disease only in 1981, after the outbreak of an epidemic among homosexuals. Just 4 years later, scientists figured out how this disease is transmitted: blood and seminal fluid. The real AIDS epidemic in the world began 20 years ago. HIV is rightly called the plague of the 20th century.
This disease primarily affects the immune system. As a result, AIDS itself does not lead to death. But an HIV-infected person who simply lacks immunity can die from a simple runny nose.
All attempts to invent it to date have failed.
How dangerous is the papilloma virus?
About 70% of people are carriers of the papilloma virus, most of them are women. Papilloma is transmitted sexually. Of the more than 100 types of papilloma virus, about 40 lead to various diseases. As a rule, the virus affects the human genitals. Its external manifestation is the appearance of growths (papillomas) on the skin.
The incubation period of the virus after entering the body can last from several weeks to several years. In 90% of cases, the human body itself will get rid of foreign microbodies. The virus is dangerous only for weakened immune systems. Therefore, papilloma often appears during other illnesses, such as influenza.
The most serious consequence of papilloma can be cervical cancer in women. 14 known strains of this virus are highly oncogenic.
Is bovine leukemia virus dangerous for humans?
Viruses can infect not only people, but also animals. Since humans eat animal products, the question of the danger of such pathogens to humans is increasingly being raised.
The leukemia virus is in first place in terms of damage. It infects the blood of cows, sheep, goats and provokes serious illnesses, and in some cases, death.
Research shows that more than 70% of people have antibodies in their blood that can fight the bovine leukemia virus. However, this does not exclude the possibility of human infection with this virus. The likelihood that bovine leukemia can lead to blood cancer in humans is very low, but there is the possibility of other negative consequences. The leukemia virus can attach to human cells, causing mutations. In the future, this may create a new strain of it, which will be equally dangerous for both animals and humans.
Although viruses can benefit people, this does not outweigh their harm. More people have died from them than have died in all the world's wars throughout time. This article listed the most dangerous viruses in the world. We hope you find this information useful. Be healthy!
They have existed since the very beginning of life on Earth. Millions of years ago there were no multicellular organisms, there were no plants, there were no animals, but viruses already flourished. If an apocalypse comes on our planet, they will still survive. Over many years of evolution, they were able to adapt to all conditions. They mutate again and again to outsmart their victims.
They developed the ability to move from species to species and mutated, changing their genetic material. Today, viruses are so complex that they cannot be controlled. Over millions of years, they have developed such a level of survival that they are now beginning to win the battle with antibiotics. Today we will touch on the topic of the deadliest strains.
Rotavirus infection
According to WHO, this merciless virus kills more than half a million children every year. It is believed that by the age of five, almost every child on the planet has suffered a rotavirus infection at least once. Fortunately, our bodies have learned to develop immunity to this type of strain. Therefore, each subsequent disease occurs with milder symptoms.
However, in countries with poorly developed medicine, the first encounter with rotavirus can be fatal for a baby. Its strains are capable of living outside the host for a long time. The transmission of bacteria itself can occur through food, water, or through dirty hands that have come into contact with an infected surface. Once rotavirus enters the body, it attacks the cells lining the small intestine. Further inflammatory processes become the cause of gastroenteritis.
Ebola fever
Ebola is a rare disease and does not typically claim more than 100 lives a year. This virus rarely spreads beyond Africa, but is dangerous because there is no vaccine or effective treatment against it. Additionally, in March 2014, West Africa experienced an Ebola outbreak that killed nearly 2,000 people. This number exceeded all previous fatal cases of the virus, which caused a great resonance in the scientific world.
Once a person becomes infected through body fluids or secretions, there is an incubation period of 2 to 21 days. The danger of this virus lies in the fact that its initial stage is often asymptomatic. Later, general malaise, headache, muscle spasms, high fever, vomiting, hemorrhage in the eye area and on the oral mucosa are observed. According to statistics, in 50-90% of patients death occurs within a few days. The likelihood of death is determined by the virulence of a particular Ebola strain.
HIV
The human immunodeficiency virus claims more than 3 million lives every year. In total, from 1981 to the present day, more than 25 million people have died from HIV. The disease is relatively new and enters the immune system through the mucous membranes and blood. Important cells of the immune system, including macrophages and dendritic cells, are soon affected. This leads to a complete weakening of the immune system, and most people with HIV develop AIDS. In the final stages of the disease, patients are at high risk of dying from pneumonia and various types of herpes.
Smallpox
Medicine officially defeated smallpox, but we could not ignore the terrible disease that claimed the lives of 300-500 million people in the 20th century alone. An acute infectious disease is localized in small capillaries of the skin, in the mouth and throat. This leads to the appearance of a characteristic rash, and later to purulent blisters. It is believed that smallpox appeared in humans around 10,000 BC. e.
This disease did not spare even monarchs and was responsible for a third of cases of blindness. The survival rate was only 20 percent, and those who survived were left with disfiguring scars on their body and face for life. After a series of large-scale vaccinations throughout the world during the 19th and 20th centuries, the WHO certified the eradication of smallpox in December 1979. Let us note that by this time humanity had managed to completely defeat only two infectious diseases.
Hepatitis B
Hepatitis B causes more than half a million deaths each year. A third of the world's population has been exposed to this virus, including 350 million chronic carriers. In China and other parts of Southeast Asia, up to 10% of the adult population are carriers. Symptoms of the disease include yellowing of the skin and eyes, dark urine, nausea, vomiting, chronic fatigue, and abdominal pain. Scientists estimate that 95% of those infected develop immunity. This disease would not be so harmless if it did not provoke chronic liver failure, cirrhosis and liver cancer.
Flu
We think the flu is harmless, but it is not. Every year, its constantly mutating strains claim the lives of half a million people. Now we have effective vaccines and new generation antiviral drugs. But in human history, influenza is known as a very effective killer. The symptoms of this disease were first described by Hippocrates more than 2,400 years ago. Pandemics have occurred approximately three times every century, resulting in millions of deaths.
The record outbreak is considered to be the Spanish flu pandemic in 1918, which, according to various expert estimates, claimed the lives of 20 to 100 million people. Influenza strains easily enter the host's body through airborne droplets or through dirty hands. As soon as the protein shells of the virus cling to cells in the respiratory tract, they immediately kill them. This leads to symptoms of cough, runny nose and sore throat. Too many damaged cells in the lungs are fatal.
Rabies
Rabies would be the deadliest condition on this list if not for successful post-exposure prophylaxis. Medicine has invented an effective injection against a zoonotic virus transmitted through an animal bite. The incubation phase of rabies can last several months before the organisms reach the central nervous system. Symptoms of rabies include severe pain, depression, uncontrollable agitation and inability to drink water.
Hepatitis C
Experts estimate that approximately 300 million people worldwide are infected with the hepatitis C virus. Most of those infected do not show any symptoms for several years. However, over time, liver damage makes itself felt. Modern medicine practices organ transplants to prevent patients with chronic liver disease from dying of cirrhosis or cancer.
Measles
Despite the invention of the vaccine, measles still claims lives (about 200 thousand per year). These sad statistics are perpetuated by third world countries whose citizens are malnourished, have weak immune systems, and do not receive adequate medical care. Over its long history, the disease has been able to kill more than 200 million unfortunate people. To date, 21 strains of the measles virus have been identified.
Hantavirus infection
Hantavirus infection, transmitted through infected rodents, is responsible for about 70,000 deaths per year. This virus is considered dangerous, although rare. Its symptoms include tachycardia and tachypnea, which lead to cardiovascular shock.
Yellow fever
This acute viral disease is transmitted through the bite of infected female mosquitoes and is found only in the subtropics. Yellow fever is native to Africa, from where, through the slave trade, the disease spread to South America in the late 16th century. In the 19th century, this virus was considered one of the most dangerous, but now medicine has effective vaccines and means of protection against mosquitoes.