There are 3,20,000 different types of viruses that can infect mammals alone. The deadliest of these viruses are responsible for killing 15 million people every year. They are ancient....   they are deadly ...... and they are found everywhere......  killing millions of people every year!

So far, there is no known form of life on earth that viruses can not infect! Let's go over the top 10 deadliest viruses the world has ever seen.


Rotavirus also is known as the child killer, is a merciless virus that causes the deaths of more than half a million children every year. It is the leading cause of severe diarrheal illness among babies and young children. 


Smallpox is one of the world's deadliest viruses that had killed more humans than any other virus in human history. With a fatality rate of up to 90%, it is responsible for killing 300 to 500 million people in the 20th century. The good news is that thanks to modern medicine, smallpox has been eradicated worldwide.


Measles has done a pretty good job of killing people throughout the ages. Over the last 150 years, the virus has been responsible for the deaths of around 200 million people. It has a yearly mortality rate of 1,97,000 deaths.


Dengue is one of the deadliest viruses humanity ha sever encountered. The virus spreads via mosquitoes. Now endemic in 110 countries dengue infects more than 100 million people a year and causes 20,000 deaths.

Yellow Fever

One of history's biggest killers is yellow fever. In severe cases of yellow fever, the virus causes bleeding from the mouth, nose, eyes or stomach. Around 50% of the patients who enter this toxic phase are dead within 7 to 10 days. Today the virus infects 2,00,000 people worldwide, killing 30,000 people each year.


Everybody gets flu and for the majority, it may not be nice but no big deal. That being said, every year, influenza is responsible for up to 5,00,000 deaths worldwide.

Spanish Flu

The most deadly flu pandemic was the Spanish flu that killed 50-100 million people. The pandemic is described as the greatest medical holocaust in history.


Rabies has been one of mankind's most feared disease since ancient times and with good reason. Infection with rabies occurs when bitten or scratched by an infected animal- most commonly by dogs and bats. Nearly 60,000 people die of rabies every year. Most of these deaths occur in Africa and southern Asia.

Hepatitis B

Hepatitis B causes the largest share of fatalities each year, with a death toll of 7,00,000. The virus attacks liver which results in either liver cancer or cirrhosis. Although the overall death rate from Hepatitis C is lower than Hepatitis B. It still kills an estimated 3,50,000 people every year.


If a virus can cause fear in the 21st century, it is the Ebola and Marburg viruses. Combined with some very unpleasant symptoms, these are potentially the deadliest viruses on earth today. Both these viruses have no effective treatment, no vaccine and a fatality rate of up to 90%.


Today, about 40 million people are living with HIV. Sadly, only around half of those infected have access to the required drugs needed for treatment, so the death rate from AIDS is still shockingly high. Estimates suggest there are nearly 2 million deaths every year and over the last 30 years the virus has claimed over 25 million lives.