The biggest killer diseases in history

The current Ebola outbreak has put the disease firmly in the global spotlight as cases exceed 10,000, with more than 4,900 deaths, according to the World Health Organisation (WHO).

However, compared to other viruses and global epidemics in history, the Ebola virus’ impact has, so far, been minimal.

Ebola first showed up in the world in 1976, according to the WHO, and has since led to the deaths of approximately 6,250 people in total.

By contrast, Malaria is reported to have wiped out half of all people who have ever lived – and continues to be one of the biggest killers today.

BusinessTech takes a look at some of the world’s deadliest diseases, and the death tolls they have left in their wake.

Due to the complexity and inaccuracy with recording causes of death on a global scale across history, the totals listed below are estimates based on available information.

HIV/AIDS was first regognised at a disease in the early 1980s, and has since grown into a global pandemic affecting millions across the globe.

According to data compiled by UNAIDS, approximately 30 million people have died due to AIDS-related illnesses since 2001 (an average of over 2.3 million people a year), with the total deaths since its discovery pegged at around 36 million people.

It’s estimated that 35.3 million people are currently living with the disease, mostly in Africa.

Cholera pandemics have struck since the 1800s, and to this day continues to affect millions of people, resulting in tens of thousands of deaths each year.

Big cholera pandemics in regions such as China, Russia and India have lead to the deaths of almost 40 million people.

One of the largest outbreaks hit India in the early 20th century, killing over 800,000 people in just over two decades.

The WHO estimates the total death toll from the 1918 flu pandemic at around 50 million casualties – however other experts on the matter believe the global impact could be as high as 100 million people.

Before and since the 1918 crisis, there have been a number of flu outbreaks, including viral strains from animals such as birds and pigs, which have also claimed millions of lives.

Record of various global flu outbreaks between as early as 1760 and up to 2009 put additional deaths due to flu close to 50 million people.

Often cited as one of the deadliest epidemics in the world, the black plague is said to have killed almost half of the population in Europe between 1346 and 1350 – with the highest death figure reported at 200 million people.

Recent scientific research into The Black Death revealed that the epidemic was a type of plague caused by the Yersinia pestis organism, which is the same organism responsible for the bubonic plague and various other plague forms.

This includes early plagues such as the Plague of Justinian (541-542AC), which reportedly claimed as many as 25 million lives, and later outbreaks of the bubonic plague in 1850s, which killed over 12 million people.

All-in-all plagues caused by Yersinia pestis have claimed the lives of well over the 200 million potential victims of the Black Death.

Smallpox is known as the only disease to be successfully eradicated, thanks in large part to global vaccination drives.

The disease had been prevalent since as early as the 16th century, and according to academics, is said to have caused the deaths of as many as 500 million people in the 20th century, alone.

Historically, smallpox had a fatality rate of 30%, though its most severe forms were almost always fatal. The last diagnosed case of the disease occurring naturally was in 1977, while the WHO declared it eradicated in 1979.

Tuberculosis, along with HIV/AIDS holds the title as the leading cause of adult mortality in the world today, killing between 1.5 million and 2 million people a year.

The WHO estimates that approximately one-third of the world’s population is infected, with less than half of all TB cases ever diagnosed.

Research suggests that as many as 1 billion people have lost their lives to TB over the past two centuries – and projections by the WHO to 2020 have a best- and worst-case scenario pointing to 60 million – 90 million deaths, respectively.

The idea that malaria could have been the cause of death for 50 billion people in human history derives from a statement from journalist Sonia Shah, whose book, “The Fever: How Malaria Has Ruled Humankind for 500,000 Years” explores the history of the disease.

Taking the statement at face-value – and assuming the speculative figures from demographer Carl Haub that over 100 billion people have lived on earth are accurate – this would mean that malaria has killed more than 50 billion people.

The figure is startling – but not completely implausible.

Author of “Parasites: Tales of Humanity’s Most Unwelcome Guests”, Rosemary Drisdelle, crunched the numbers using both Haub’s numbers and Shah’s claim, noting that if most people died between 8000BC and 1650AD, this could account for 5.4 million deaths a year.

Considering the lack of treatment that would have been available, and the fact that the disease has apparently been with humanity for 500,000 years, it’s not completely implausible.

In 1999, the WHO reported that malaria could have claimed the lives of close to 200 million people in the 19th century alone – and the group’s contemporary death figures say as many as 1.2 million deaths a year are still being attributable to the disease.

Taking this into account, it’s clear that malaria is the world’s biggest killer disease, having claimed billions of human lives.

“Did malaria kill between 53 and 54 billion of the 96 billion who lived before 1900? I’m neither an epidemiologist nor a statistician…We’ll never know for sure, but based on my reading I think it’s possible,” Drisdelle said.

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