Top 10 Deadliest Viruses in Human History

Viruses and viral infections existed in human beings from more than 12,000 years ago during the Neolithic period. Early human beings lived in isolation, small in numbers and epidemic diseases didn’t exist. But, the modern human being is more displaced and large in numbers that has caused a variety of epidemics and viral infections. The most lethal and devastating Smallpox virus first emerged in India’s agricultural communities some 11,000 years ago. Herpes viruses are known to have infected the ancestors of modern human beings some 80 million years ago. During those times of the world, the immune system was not prepared for the new foreign agent, and people infected would succumb to the virus. The acquired immunity got passed on and on from our ancestors, the human body adapted to the more common viruses easily. But, due to mutations of the strain within human beings or within animals has caused sudden pandemics and epidemics in the world killing millions. Many variations of the same viruses are prevalent in the society today. One of the most common stain is the influenza that starts with H1N1 (Spanish Flu and Swine Flu), H2N2 (Asian flu), H3N2 (Hong Kong Flu), H5N1 (Bird Flu) and so on. So which are the top 10 deadliest viruses in human history?

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Here is the list of 10 deadliest viruses in human that caused diseases with high mortality rates:

10. Influenza A virus subtype H5N1 (Mortality Rate – 60%)

H5N1 Virus - Bird Flu

Influenza A virus subtype H5N1 is also known as “Bird Flu” virus. The deadly H5N1 virus first infected the humans in 1997, since than it has killed 60% of the infected patients. The virus gets transmitted to humans by birds. A study conducted by few researchers has confirmed why the virus is so deadly to humans. The research revealed that the virus can trigger 10 times more inflammatory proteins than H1N1 virus. These unusual levels of viral inflammatory proteins lead to severe life-threatening pneumonia and acute respiratory distress in human beings. The avian influenza is actually a poultry virus that is deadly to even birds. Apart from respiratory complications other symptoms such as vomiting, diarrhea and common flu-like symptoms are also prevalent. The virus causes severe multi-organ failures as well.

9. Lujo virus (Mortality Rate – 80%)

Lujo Virus

Lujo virus got its name after the 2008 outbreak in Lusaka (Zambia) and Johannesburg (Republic of South Africa). The first two letters of the two cities led to the name Lujo virus. Luju virus is a cruel virus that has a case fatality rate of 80%. In the 2008 outbreak that infected 5 people, 4 people died. Scientists have described this virus as fatal as Ebola virus. The first outbreak is known to have been due to a female travel agent living in the outskirts of Lusaka. She suffered from severe fever that grew worse over time. The deadly Lujo virus is known to cause viral hemorrhagic fever (VHF) in humans. The virus is known to cause symptoms similar to Ebola like bleeding gum and nose.

8. Herpes B Virus (Mortality Rate – 80%)

Herpes B Simplex Virus

Herpes B Virus is highly harmful and has a case fatality rate of 80%. Herpes simian B virus is a simplex virus of macaque monkeys that travel from one host to another using the peripheral nerves. The virus affects the central nervous system and leads to nervous breakdown or death if untreated. Proper on-time diagnosis and treatment is required for human survival. Since the discovery of the Herpes B Virus in 1932, there are 31 documented cases of the infection, 21 of which led to death. The disease is rare among humans, but it is easily transmissible via monkeys or animal bites. It has been found that about 80 to 90% of the rhesus monkeys are carrying the Herpes B Virus. Some of the important symptoms of the viral infection include shortness of breath, muscle in-coordination and fever.

7. Dengue Virus (Mortality Rate – 20-30%)

Dengue Virus

Dengue virus is another lethal virus in the world that is transmitted through mosquitoes to human beings. The mosquito-borne RNA virus causes the deadly dengue fever. Researches have shown that there are several types of strains. Developing a vaccination against the virus has been difficult to scientists as the vaccination should be effective against all the strains of dengue virus. The virus is closely related to another deadly mosquito-borne virus called zika virus. The combination of dengue virus with zika virus or chikungunya can cause extremely fatal complications, especially in pregnant ladies. When this virus strikes, the symptoms can range from vomiting, fever to headaches. In some cases the virus can cause the life-threatening dengue hemorrhagic fever where the patient bleeds from nose and the blood pressure drops to dangerously low levels. Approximately 10,000 to 20,000 people die each year due to this virus out of the 50 to 500 million infected.

6. Rabies Virus (Mortality Rate – 100%)

Rabies Virus Microscopic

Rabies virus is a neurotropic virus that causes rabies in human beings. The virus is transmitted through saliva of animals and via human fluids. In 2009, a severe outbreak of rabies killed 93 children in Angola. Close to 55,000 people die annually of rabies. The zoonotic viral disease spreads via animals like cats, bats, dogs, monkeys and mongoose. In 2010, rabies virus killed 78 people in the islands of Bali, Indonesia. Rabies virus is dangerous when the patient is not treated with vaccinations. The virus acts 100% when symptoms develop. The virus is fatal because it directly affects the brain and nervous system of human beings and animals. Symptoms of the viral infection could range from hydrophobia to inability to move. If symptoms appear the fatality rate is nearly 100% always.

5. 1918 “Spanish Flu” Virus – The H1N1 Influenza Virus (Mortality rate – 2.5-50%)

Spanish Flu Virus - H1N1 Virus

Spanish flu virus is one of the first H1N1 influenza virus that caused a deadly pandemic in the 1918. The 1918 pandemic that killed 50 million people – the fastest kill ratio in history by a virus. The virus killed more people than in the Great War or the World War I. The virus had caused a devastating scene in the United States that decreased the average life span in the US by 10 years. Even after nearly a century, epidemiologists today are still plagued by the mysterious epidemic. The name Spanish Flu came for the reason that it killed 8 million people in Spain (The highest mortality rate in any country) during 1918 and Spain media was the first to report it. The exact origin of the virus is still unknown. Some believe that the deadly strain of influenza originated somewhere from China. A reverse-genetics team of scientists have controversially recreated the virus from a dead soldier’s body in 2014. The move has been highly condemned by the scientific community worldwide. The H1N1 strain is known to have caused some of the major damages to the human society in terms of kills by pandemics such as Spanish Flu, Russian Flu, Asian flu and Swine Flu.

4. Ebola Virus (Mortality rate – up to 90%)

Ebola Virus

Ebola virus is a deadly virus which causes the Ebola Virus Disease which was formerly called as Zaire Ebola virus. The virus was first discovered near a river by name Ebola in Zaire in 1976. Ebola Virus Disease was previously known as Ebola hemorrhagic fever which is a severe and fatal illness among human beings. The virus has a high human mortality rate of 90% and some Sudan variant has 53% mortality rate. The initial symptoms of the virus are similar to the common viral influenza with sore throat, fever, muscle pain and headache. The next stage symptoms could be vomiting, diarrhea, blood in stool, rashes, and kidney and liver impairments. If the patient is not treated early on could be deadly and life threatening.

3. Smallpox Virus (Mortality rate – 95%)

Smallpox Virus

Pic Credit: Photography by

Smallpox virus is one of the world’s deadliest viruses that had killed more humans than any other virus in human history. In 20th century alone the virus killed about 200-500 million people worldwide. The virus was evident in history from 10,000 BC. Today, smallpox is a disease that has been completely eradicated. The highly contagious, acute and fatal smallpox is caused by orthopoxvirus which is distinguished by high fever, bumpy rashes, pus-filled blisters, vomiting and body aches. There is a chance of death by up to 30% in smallpox cases. The mortality rate due to smallpox is approximately 95% which is fatally high.

2. Marburg Virus (Mortality rate – 23-90%)

Marburg Virus

Marburg virus is a deadly infectious virus that causes Marburg Virus Disease also known as Marburg Hemorrhagic Fever. The virus has a very high mortality rate of 23 to 90% in patients who are untreated. In most of the cases hemorrhage or blood loss is not the cause of death but due to multiple organ dysfunction syndrome (MODS). The virus is considered to be extremely dangerous. The dangerous agent was first discovered in 1967, when an outbreak occurred in Germany’s Frankfurt and Marburg laboratories synchronously. 31 patients developed symptoms of hemorrhagic fever that resulted in deaths of 7. Survivors of the disease have experienced prolonged ocular problems, hearing loss, muscle weakness, hepatitis and many other problems.

1. HIV (Mortality rate – 80-90%)

HIV Virus

A. Harrison, P. Feorino; E. L. Palmer

Human Immunodeficiency Virus is the world’s most dangerous and deadliest virus known to human beings that kills millions of people each year. HIV in itself is not a deadly virus to human beings, but the virus has lots of tricks to shut down the cells responsible for the body’s immune system. HIV causes a serious condition well-known by the name Acquired Immunodeficiency Syndrome (AIDS). HIV attacks a special type of immune cell in the body known as CD4 lymphocyte. When the body loses its defense system due to the attack from HIV, the body gets serious infections which otherwise is not contracted. The virus ultimately kills its victim due to other respiratory infections like tuberculosis and pneumonia. The virus can even cause certain cancers. The person gets weaker day by day leading to death. People with diabetes and asthma are more likely to get killed sooner. But, healthy people if treated can live long. There is no particular cure, but scientists are trying hard to find a cure. Soon there will be medicines to cure AIDS completely. AIDS is transmitted via physical contacts, bodily fluid contacts and via pregnancy to the child. In 2014, 36.9 million people were infected with AIDS, out of which 1.2 million people died due to AIDS related diseases.


Vinod Suthersan is an young tech enthusiast, Blogger addict, Internet craze and thriving to learn new things on the world of Internet.

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