Viruses. We can't see them, but we can feel their dreadful impact. In 2020, the Coronavirus outbreak is shocking the world by rapidly spreading throughout the 5 continents. The often fatal COVID-19 is considered to be a worldwide pandemic, but it's not the first known case of a deadly, easily-spread virus.

Throughout history, the impact of these small infectious organisms that live inside cells is known to have killed millions, endangering entire civilizations and wiping out enormous percentages of the world's population. No matter how evolved society gets, it seems we cannot get around it... Today, we take a look at the 37 deadliest viruses ever known to men.

Marburg Virus

472 Infected, 380 Died - %80.5 Fatality Rate

The Marburg Virus was first spotted in 1967 in the German cities of Marburg (hence the name) and Hamburg. With symptoms similar to the ones associated with the Ebola Virus, the Marburg Virus is rated as a Risk Group 4 Pathogen and considered to be one of the deadliest, most dangerous viruses ever discovered.

The Marburg Virus can cause high fever and internal bleeding, which might result in organ failure, dehydration, and death. The virus' mortality rate can go up as high as 80%. It's the value registered during one of its latest outbreaks, which took place in the Democratic Republic of Congo in the late '90s.

Ebola Virus

28,652 Infected, 11,325 Died - %39.5 Fatality Rate

The first Ebola virus outbreak happened during 1976, striking the Democratic Republic of Congo and Sudan simultaneously. The virus is known for causing a dangerous hemorrhagic fever with a very high case of fatality rate, although there are major differences between its 6 known species. It can kill up to 71% of the people infected.

The Western African Ebola virus epidemic was the largest outbreak of the disease ever. Between 2013 and 2016, the countries of Sierra Leone, Guinea, and Liberia were highly affected by the Ebola virus. The official numbers of the World Health Organization (WHO) reported a total of 11,323 deaths.

Rabies

Unknown Infected, 59,000 Died - Undetermined Fatality Rate

Over 99% of rabies cases are originated by dog bites. As a result, rabies vaccines for pets are widespread and often mandatory in the developed world. Considered to be the most deadly virus ever discovered, rabies has a mortality rate of almost 100%. Luckily, treatments for rabies are available.

Even though rabies can be cured through vaccines and antibodies, it continues to strike poor communities in Asia and Africa. The two continents register 95% of all known rabies fatalities, and the disease reportedly costs $124 billion every single year. The latest rabies outbreak happened in 2015 and resulted in approximately 17,400 deaths.

HIV

72 Million Infected, 32 Million Died - %44.4 Fatality Rate

HIV is one of the best-known and most dangerous viruses ever discovered. The life expectancy of the infected sits between 9 and 11 years, depending on the HIV strain. The HIV death rate peaked in the mid-'90s at 16.3%. Yet, the virus has resulted in the death of an estimated 36 million people since the early '80s.

HIV was first discovered in 1981 in the United States. The disease is believed to have originated in primates living in West-central Africa, but can now be found all over the world. Swaziland, where 27.3% percent of the population has the virus, is the most HIV-infected country on the planet.

Smallpox

1.6 Billion Infected, 500 Million Died - 31.3% Fatality Rate

In 1980, the WHO announced that smallpox had been eradicated from the world. Its origin is unknown, but the symptoms were unmistakable. Smallpox-infected people were characterized for having their bodies covered with fluid-filled bumps that caused scars. Other symptoms included vomiting and fever.

Fortunately, those born after 1980 have been given a chance to live in a Smallpox-free world. Throughout history, smallpox was one of humanity's biggest scourges. It killed over 400,000 people in 18th-century Europe alone, including 4 reigning monarchs. In its final 100 years of existence, smallpox killed an estimated 500 million people.

Hantavirus

728 Infected, 262 Died - 36% Fatality Rate

Hantavirus is an infectious virus spread through rodent-related fluids, such as saliva and excrement. Although scientists believed for years that it couldn't be passed between humans, the first human-to-human transmissions were registered in South America in 2005. Common amongst mice, the Hantavirus has a 36% death rate amongst infected humans.

The first human outbreak of the Hantavirus happened in South Korea, in the area surrounding the Hantan River. There are reported cases of Hantavirus in each of the world's 5 continents, but the virus is believed to be rare. The latest Hantavirus outbreak happened in 1993, in the American states of Arizona, Utah, New Mexico, and Colorado.

Influenza

45 Million Infected Annually, 61,000 Die Annually - 0.14% Fatality Rate

Influenza can be referred to as "the flu", and its symptoms include all of the things we normally associate with a regular Winter-time flu: runny nose, joint pain, constant cough, and high fever. But influenza is not only particularly deadly but also exceptionally lasting. We have been dealing with Influenza since the 19th century and there seems to be no way around it.

In the 20th century alone, three registered Influenza pandemics resulted in the dead of a whopping 103 million people. The biggest was the Spanish Influenza pandemic, which started in 1918 and affected 27% of the world's population. 100 million people died during the outbreak.

Dengue

390 Million Infected Annually, 25,000 Die Annually - 0.007% Fatality Rate

Like many other tropical viruses, Dengue is most common in low-income countries in the continents of Asia, Africa, and South America. It was first registered in 1779 and became a global problem after the end of World War II. Dengue's symptoms include a characteristic skin rash, as well as fever, vomiting, headaches, and muscle pain.

Spread through mosquitoes, Dengue can be sub-divided into 5 different strains. Although Dengue is not commonly found in developed countries, it is still unbelievably usual in third world countries, infecting 390 million people every year and resulting in approximately 25,000 yearly deaths.

Rotavirus

111 Million Infected Annually, 444,000 Die Annually - 0.4% Fatality Rate

Rotavirus can sometimes be confused with gastroenteritis due to the nature of its symptoms. Incredibly common amongst children, it is believed that almost every child over 5 years old was infected with Rotavirus at least once. Treating the virus is not that hard. However, negligent medical practices and poor living conditions allow Rotavirus to kill an estimated 37 children every year.

How can we identify Rotavirus? If a small child or young teenager is experiencing strong diarrhea, it is highly likely he/she has Rotavirus. In such cases, keeping your child hydrated should be your number 1 priority. In some of the world's countries, the Rotavirus vaccine is mandatory.

Lassa Fever Virus

400,000 Infected Annually, 5,000 Die Annually - 1.25% Fatality Rate

The Lassa mammarenavirus was first contracted in Nigeria in 1969. Only 20% of the people infected with the virus become symptomatic, which contributes to its spreading and difficult diagnosis. Most commonly known as the Lassa Fever virus, the disease is characterized by viral hemorrhagic fever and can cause deafness.

Relatively common in West African countries, the Lassa Fever virus affects about half-a-million people in the region every single year, with the annual number of fatalities sitting over the 5,000. So far, there's no cure or vaccine available to treat the Lassa Fever virus.

Hepatitis B

391 Million Infected, 750,000 Died - 0.19% Fatality Rate

Hepatitis B is a highly infectious virus affecting 5% of the world's population. Although it can be contained and there's a 95%-effective vaccine available since 1982, Hepatitis B is still one of the world's deadliest viruses, resulting in the estimated death of about 750,000 people every year.

While Hepatitis B is often a-symptomatic, the virus can be in the origin of some serious health complications, leading to the development of cirrhosis and liver cancer. It is transmitted via body fluids, such as blood and semen. In the '80s, the popularization of tattooing and acupuncture helped the virus to spread in developed countries.

Hepatitis C

143 Million Infected, 496,000 Died - 0.34% Fatality Rate

The Hepatitis C virus can be easily associated with Hepatitis B. Both viruses affect the liver and can result in cirrhosis and liver cancer. However, the Hepatitis C virus is slightly less common and cannot be prevented by vaccines. Found mostly in Africa and Asia, it is estimated to affect 11 million people every year.

The disease only infects humans and chimpanzees. It is believed that about 2% of the world's population (approximately 143 million people) is infected with Hepatitis C. The virus is usually transmitted via unsterilized blood transfusions and needle sharing, which makes it very common amongst Heroin users.

Measles

20 Million Infected Annually, 73,000 Die Annually - 0.36% Fatality Rate

The measles virus is normally associated with children, but it can affect people of all ages. Characterized by high fever, runny nose, and red eyes, it can also be in the origin of complications such as diarrhea, ear infection, and pneumonia. Luckily, measles can be prevented with a very effective vaccine.

Over the last few decades, the number of registered cases of measles virus has been dropping considerably. In 1980, 2.6 million people died from the disease, but the death rate's been fortunately getting lower. By 2014, the number of estimated deaths caused by the virus was reduced to 73,000.

Yellow Fever

200,000 Infected Annually, 30,000 Die Annually - 15% Fatality Rate

Yellow Fever is a viral disease characterized by chills, nausea, loss of appetite, and fever. Normally, these symptoms improve after 5 days, but they can sometimes result in major health complications such as liver damage and kidney problems. About 90% of all registered cases of Yellow Fever occurred in Africa, but the virus is also common in South America.

Over the last few years, climate change has helped the virus to spread. The Yellow Fever comes from mosquitoes, who have been extending their natural habitats over the last decade due to Global Warming. In 2013, 45,000 people died after being contaminated with the virus.

H5N1 (Bird Flu)

861 Infected, 455 Died - 52.8% Fatality Rate

When it first started making headlines in the news in the late '90s, the notorious Bird Flu, also known as the H5N1 virus, seemed like a much worse virus than it proved to be. The H5N1 is not, by all means, harmless, but it has a relatively low body count.

Between 2003 and 2013, the WHO registered only 375 deaths out of 630 confirmed human cases. There is no evidence that the Bird Flu can be transmitted between humans, and an effective vaccine against it is commonly used to treat possibly contaminated aviary birds.

Anthrax

2,000 Infected Annually, 480 Die Annually - 24% Fatality Rate Without Treatment

Anthrax first appeared in the news after the 2001 Anthrax attacks, which happened only a week after the 9/11 terrorist attack. Letters containing the bacteria were sent to high government officials and resulted in the assassination of 5 people, shocking an already stunned post-9/11 America.

Fortunately, Anthrax is not so dangerous if not purposely used for evil. Being a bacteria, it can be effectively cured with antibiotics, assuming that the people infected look for medical treatment as soon as possible. Although rare (about 2,000 people are affected every year), Anthrax is commonly used as a chemical weapon and it's part of the arsenal of several countries.

The 2019 Novel Coronavirus

360,674 Infected, 15,491 Died - 4.29% Fatality Rate (So far)

The 2019 novel Coronavirus has been dominating the news ever since it first appeared, and there are good reasons for it. Now considered to be a global pandemic, the virus has rapidly spread throughout the world and resulted - so far - in the death of close to 5,000 people.

The outbreak started in the Chinese province of Hubei. Since then, it has rapidly spread to Japan, South Korea, and Italy, which is the 3rd most infected country in the world. A cure is still not available, but approximately 70,000 of the 130,000 people infected have shown signs of complete recovery.

Malaria

219 Million Infected Annually, 403,000 Die Annually - 0.19% Fatality Rate

Spread through mosquitos, malaria is one of the most resilient diseases affecting the countries near the equator. Characterized by fever, headaches, vomiting, and fatigue, registered cases of malaria have increased since 2015. In 2018 alone, the virus was responsible for killing 405,000 people and infecting over 228 million.

Associated with poor communities living in under-developed countries, 94% of malaria-related deaths have occurred in Africa. The disease has a dramatic economic impact in the region, with the WHO estimating that it costs around $12 billion every year. There is no vaccine for malaria, but the virus can be prevented by controlling the mosquito population.

Tuberculosis

10 Million Infected Annually, 1.6 Million Die Annually - 16% Fatality Rate

Tuberculosis has been around since ancient times, and we still haven't been able to figure out a way to effectively deal with it. In 2017, 1.6 million people died from TB, which makes it the number 1 deadliest infectious disease in the world. As of 2018, it is estimated that 25% of the world's population is infected with tuberculosis.

This deadly bacteria is highly contagious and normally spread through the air. When logged inside the body, it usually goes for the lungs and results in night sweats, severe weight loss, and blood-filled cough. It is most commonly found in Southeast Asian countries such as India, China, and the Philippines.

Zika Virus

500,000 Infected Annually, 18 Died - 0.0036% Fatality Rate

The Zika virus is similar to Dengue in many ways. The symptoms are almost the same, and the virus can also be found in mosquitos. It was first isolated in 1947, in the Ugandan Ziika Forest. Although the virus has been studied since the early '50s, there's still no available vaccine.

The Zika virus can be transmitted during a prenatal stage, passing on from pregnant mothers to their children. At this stage, the Zika virus is incredibly dangerous. Newborn children infected with Zika can be born with microcephaly and several other brain malformations.

Human Papilloma Virus

14 Million Infected Annually, 260,000 Die Annually - 1.9% Fatality Rate

Just like TB, the human papillomavirus (HPV) has been around since ancient times. A virus exclusive to humans, it is generally transmitted through intercourse. On most occasions, a person can have HPV without even noticing it. It is safe to say that a large percentage of the population is or was infected with HPV at one point in their lives.

While common, HPV can be incredibly dangerous. In 1% of all HPV cases, the virus can cause cancer and other major health complications. Especially damaging for women, HPV can be in the origin of all sorts of genital problems and result in infertility.

Acute Flaccid Myelitis

613 Infected, 2 Died - 0.32% Fatality Rate

The number of Acute Flaccid Myelitis (AFM) cases has been rapidly increasing since 2014, although the condition is still considered to be very rare. AFM affects the spinal cord and is normally preceded by a mild infection. The virus damages the grey matter present in the spinal cord, which results in serious neurological consequences.

The condition is often compared to polio and mainly affects children. There is no exact way of avoiding AFM, which origin is still unknown, but the polio vaccine might be effective in preventing it. In 2018, official medical reports confirmed the existence of 233 new cases of AFM in the United States.

MERS-CoV

720,000 Infected Annually, 720 Die Annually - 0.1% Fatality Rate

The Middle East respiratory syndrome-related coronavirus (MERS-CoV) was discovered by the Egyptian virologist Ali Mohamed Zaki in 2012. One of the newest viral conditions known to men, the MERS-CoV is considered to be highly dangerous by the WHO, which has classified it as a probable future epidemic.

The disease can affect humans, bats, and camels, and it has a mortality rate of over 30%. As a fairly new condition, effective MERS-CoV treatment is still not available. The MERS-CoV virus was identified in over 20 countries, most of which are located in North Africa, the Middle East, and Southeast Asia, but also Europe and the U.S.

BK Polyoma Virus

Undisclosed Information

To this day, scientists have still not discovered how the BK virus is transmitted. The virus is often asymptomatic and harmless, but it can be in the origin of some troubling health complications. The medical community believes about 80% of the population has some kind of latent form of BK virus in their organism.

Although remarkably common, the BK virus is only dangerous when the body goes through some form of immunosuppression. Such is the case with organ transplants. People infected with the virus should be extremely careful when undergoing one of these tricky procedures, especially if it involves kidney transplantation.

African Sleeping Sickness

11,000 Infected, 3,500 Die Annually - 31.8% Fatality Rate

The African trypanosomiasis virus is most commonly known as African Sleeping Sickness. Transmitted via the Tsetse fly, the disease features some dreadful symptoms, which include confusion, lack of coordination, trouble sleeping (hence the name), and numbness.

Over 80% of all registered African Sleeping Sickness cases happened in the Democratic Republic of Congo. The infectious disease is also very common in other countries of the sub-Saharan region of Africa, such as Congo and Uganda. In 2015 alone, 3,500 people died after being infected with the virus. The disease affects humans and animals alike, and a large population of cows is known to be infected.

Macacine Alphaherpesvirus

31 Infected, 21 Died - 67.7% Fatality Rate

Macacine alphaherpesvirus 1 is the scientific name attributed to a specific subset of herpes. Unlike common herpes, the Macacine alphaherpesvirus 1 is extremely rare and extremely dangerous. The virus infects mostly macaque monkeys, but there are over 30 identified cases of human incidences since its identification in 1932.

The virus focuses on attacking the central nervous system and can lead to the development of encephalitis. The mortality rate of the Macacine alphaherpesvirus 1 sits near 80%, with 21 out of the 31 documented human cases resulting in death. In 1997, the macaque researcher Elizabeth Griffin got infected after being splashed in the eye by one of the primates she was studying.

Bubonic Plague

650 Infected Annually, 116 Die Annually - 17.8% Fatality Rate

Bubonic plague is a sub-type of plague which is normally associated with the Great Bubonic Plague. The Great Bubonic Plague, or Black Death, was a major bubonic plague outbreak that killed up to 200 million people in Europe and Asia in the 14th century. One of the deadliest, most impactful pandemics ever registered, the Great Bubonic Plague had major social-economical consequences.

The plague is characterized by flu-like symptoms: fever, headaches, and vomiting. It is normally spread through small animals like fleas. Today, the Bubonic plague can be treated and has a relatively short mortality rate of 10%. When untreated, it can kill up to 90% of the people infected.

Cancer (Not A Virus)

17 Million Suffer Annually, 10 Million Die Annually - 58.8% Fatality Rate

It's not surprising that most people fear cancer above all other types of diseases. This scourge is believed to kill almost 9 million people every single year, and researchers are still desperately trying to find a cure. Cancer diseases are characterized by abnormal cell growth and are sometimes hard to spot. Humans are affected by over 100 different types of cancer.

It's impossible to avoid cancer completely, but some practices can help to prevent it. Eating healthy and staying active is very important, as it is keeping away from tobacco and alcohol. Cancer can also be caused by overexposure to sunlight.

Typhoid Fever

12.5 Million Infected Annually, 149,000 Die Annually - 1.19% Fatality Rate

Typhoid fever is caused by a specific type of Salmonella bacteria and only infects humans. In 2015, over 12 million new cases were registered. The disease is spread through the feces of the people contaminated and it's associated with poor hygiene and low-quality sanitation. For that reason, it's more common in under-developed countries.

Normally treated with antibiotics, typhoid fever has a mortality rate of 20%, but the number drops to 4% in cases involving proper medical treatment. Although cases of typhoid fever in developed societies hardly involve the risk of death, the disease is known to kill close to 150,000 people every year.

Leprosy

209,000 Infected Annually, 18,810 Die Annually - 9% Fatality Rate

Leprosy is caused by the M. leprae bacteria and it's spread via contact with contaminated body fluids. One of the world's oldest contagious diseases, leprosy has been around since ancient times. It's characterized as an infection damaging the nerves, skin, eyes, and respiratory tract.

Unlike what's commonly believed, leprosy doesn't result in the loss os extremities like arms and legs. However, the infection can result in a lack of ability to feel pain, which makes it easier for the infected to contract serious injuries in their bodies, without even noticing it. In 2018, about 209,000 new cases of leprosy were registered.

Hepatitis A

114 Million Infected, 11,200 Died - 0.09% Fatality Rate

Hepatitis A is an infectious disease attacking the liver, which can result in acute liver failure. Fortunately, cases of hepatitis A don't normally get that serious. Typical hepatitis A symptoms include abdominal pain, nausea, diarrhea, fever, and icterus. Still, over 11,000 people died from hepatites A-associated causes in 2015 alone.

Hepatitis A is incredibly common in under-developed countries, with some studies claiming that 90% of children living in risk areas are exposed to the infection before turning 10 years old! Luckily, hepatitis A lasts only for about 5-8 weeks. Additionally, people normally get immune to the disease after one single infection.

Meningitis

8.7 Million Infected Annually, 379,000 Die Annually - 4.3% Fatality Rate

Meningitis is a bacteria-related disease characterized by acute inflammation of the membranes covering the brain and spinal cord. Regular symptoms include neck stiffness, fever, and headaches, but meningitis can result in serious long-lasting health complications such as deafness, epilepsy, and hydrocephalus (which causes increased pressure inside the skull).

Particularly troubling for the infected children, meningitis kills close to 380,000 people every year. It is so common in the sub-Saharan African region that the geographical area was even named the "African meningitis belt". In this area, yearly outbreaks of meningitis are normally registered between December and June.

Spanish Flu

500 Million Infected, 50 Million Died - 10% Fatality Rate

Commonly known as the Spanish Flu, the 1918 influenza pandemic was one of the deadliest epidemics in history. It had such a great impact on the U.S. citizens that it single-handedly dropped the life expectancy rate of the country by 12 years! It is known to have killed at least 17 million people, but recent studies have concluded that the real number of influenza-related deaths was probably as high as 100 million.

Investigators have pointed out that the 1918 outbreak of Spanish flu wasn't different from the previous Spanish flu outbreaks. However, the impact of the disease was heavily fueled by malnourishment and poor living conditions.