The 10 Worst Diseases Ever


#1 Bubonic Plague:

Also known as “The Black Death,” getting infected used to be like being stopped by Death and asked to flip a coin.  Heads you live, tails you die.

Death is pretty horrible, with parts of your body bubbling into large nodes, blood vomiting and your skin partially peeling off.

One sweep of this epidemic killed one out of three people in Europe.  It’s that bad, and a faster form can kill you several hours after exposure.

Yet this disease was conquered by the invention of antibiotics.  With the ever happening evolution and change, however, it is entirely possible that Black Death will develop resistance to the medications we have.

Death count: 200 million people total

Poster against TB

#2 Tuberculosis (TB):

You don’t hear much about this disease, romantically named “The White Plague.”  Which is downright mind-boggling.

Currently, 1/3 people in the entire world are infected with TB.  It is the worst killer disease currently on the market, reaping several million deaths a year.  One person is infected per second.

Thankfully, most cases don’t result in disease.  That said, 10% do.  Symptoms typically start off mild, then progress to a severe cough, extreme exhaustion and weight loss.  Over time, TB eats away at your lungs, and you spit out blood.

Also known as “consumption,” because being infected is much like slowly being consumed alive.

Like its cousin The Black Death, TB can be treated by antibiotics.  Doing so, however, can take up to six months, meaning that hardly anyone follows the treatment regime and progressively more resistant and nasty strains are emerging by the year.

Death count: 2 million annually

Kaposi's Sarcoma on skin

#3 Acquired Immunodeficiency Syndrome, AIDS:

We didn’t know that AIDS or the virus that causes it, HIV, existed thirty years ago.

Yet since then it has killed more than 20 million people.  AIDS has almost caught up with Tuberculosis in terms of just how many million lives it takes a year, with one key difference:  There is no permanent cure.

The symptoms of this disease are confusing and many.

They can range from weight loss and diarrhea, to railroad rings of fungus growing in your throat and tumorous blotches of red and blue spreading over your skin.  In many cases, the disease reaches the brain and causes dementia.

By itself, AIDS reduced life expectancy in many African countries from 50 years to something like 25 years.  So in parts of Africa, the coming of AIDS meant that the average person could expect to live half as long.

Nothing about this disease is comforting, besides some of the excellent yet still lacking research and innovation it has prompted.  Even with the treatment we have, a combination of drugs, life expectancy after infection with HIV is sharply reduced.

Death count: 2 million per year


Mosquito taking a blood meal

#4 Malaria:

Malaria is a heartbreaking disease.  It kills 1-3 million people annually, and infects up to half a billion people per year.

Yet most of these cases occur in poor parts of the world.  It is my belief that if malaria were endemic to wealthier parts, such as the USA, more effective treatments and even a vaccine might have been found already.

Until that happens, half a billion people annually can expect to suffer from vomiting, intense shivering, and even convulsions that occur cyclically every few days.

Death count: 1-3 million per year


A child infected with Smallpox

#5 Smallpox:

Smallpox is mostly a historical issue because it is the first disease we, together, eliminated from the world.  And thank God we did.

Doing so was made easier by how nasty and vicious it is.  Highly contagious, smallpox kills roughly 30% of those infects, and typically permanently scars those it doesn’t.  That made it relatively easy to figure out where in the world it is.

Because smallpox doesn’t mutate rapidly, we were able to develop a vaccine to it.  Then we initiated mass vaccine efforts, getting as many people vaccinated as possible.  And then we carefully figured out where it was occurring, vaccinated everyone in those areas, and kept reducing its territory.

In 1979, a monumental date for people who study diseases (that’s me!), we officially kicked this disease off the planet.

That is except for the medical weapon research facilities where it still exists.  Because people aren’t vaccinated against it anymore, smallpox could theoretically come back at any time, possibly by a terrorist attack.

Death count: 300-500 million in 1900s alone

a human heart

#6 Heart Failure:

By one way or another, your heart stops working.  Not exciting, not dramatic, not infectious or contagious.  But it means this: you die.

Heart disease is by far the single worst killer of men and woman in the United States, easily outdoing cancer.

A lot of things cause heart failure, ranging from the quick and nasty – a heart attack – to the slow and insidious – high blood pressure, or high cholesterol.

Death count: 1 person per 34 seconds in the USA alone


No.5, 1948 Jackson Pollock Painting

#7 Schizophrenia:

What if I told you that you had a one in a hundred chance of waking up tomorrow and either hallucinating, becoming paranoid, or delusional?

Pretty scary.  Yet some estimates put the prevalence of schizophrenia, a psychological disorder, at about that rate.

It’s hard to do justice to this condition, which takes away your most precious asset: your mind.

Not to mention that there is still no cure, although we do have treatments.  Treatment, however, is far from ideal, and long term use can cause permanent twitches, diabetes and other problems.

And even if you take the strongest dose of anti-psychotics, that doesn’t guarantee that the psychosis will stop.  For a condition so common, we know almost nothing about it.


3D Influenza virus

#8 Influenza:

A quiet disease that typically takes you out of commission for a week, but not much more.  While it kills tens of thousands of people per year in the USA, that doesn’t make it one of the worst diseases ever.

What does is this:  About once every 20-40 years, influenza mutates and a pandemic happens.  That can turn the tens of thousands of deaths into tens of millions.

The good news is that we can make vaccines to the flu.  The bad news?  That it mutates so rapidly that in just one year our vaccines are outdated.

Most experts agree it’s only a matter of time before another deadly flu pandemic arises.  Imagine a swine flu that kills 10% of those infects.

Death count: 100 million total


a worm

#9 Schistosomiasis:

Now this one I could almost bet you haven’t heard of.

Schistosomiasis is a condition where a worm crawls into your skin, takes up residence in your liver, and starts chewing, occasionally spitting out eggs that are covered in spikes.

Doesn’t sound fun, and for the 200 million people currently infected with this disease, it isn’t.  Being infected with blood sucking worms really, really sucks.  Here’s just one problem it causes: Sometimes the eggs embed in your genitals, causing you to urinate blood.

And the worm is simply too tough for your immune system to kill.

Of course, most cases are caused by contaminated water.  And we have drugs that kill the worm pretty quickly and efficiently.  So in wealthier countries, this condition is simply not a major problem.

Of course, because most cases are in poor countries, people don’t get treated, and the poor water supply keeps the epidemic going.

The economic impact of “schisto” is tremendous, and just one more problem too often overlooked.


Epidemic typhus Burundi

#10 Typhus:

Another disease you don’t hear much about, but one that’s taken its share of millions.

Also known as “war fever,” Typhus is spread by fleas, and especially thrives in the crowded conditions of army barracks.  It killed a large percentage of Napoleons army, and killed millions of soldiers in World War I.

Infection starts with a headache and loss of appetite.  Your temperature then shoots up so high that you’re quite likely to become temporarily delirious.

This can last for up to two weeks, and up to 40% of those infected die.

Nowadays, with a Typhus vaccine as well as better sanitation and less fleas, the disease isn’t much of a threat – to developed countries.  Elsewhere, it still rampages.

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29 thoughts on “The 10 Worst Diseases Ever

  1. Im surprised rabies didnt make the list. The mortality rate is nearly 100% seeing how there has only been three survivors since 2011. So when this post was made, there was less than or even no survivors. Although a vaccine is in place to prevent the spread over 55,000 die annually and thats after the vaccine. Imagine what it was like before hand and in the previous times! Im just confused by the placement of these diseases and what you have chosen. I would have though the mortality rate of this disease was significant enough to put on the list. lol

  2. @Justin     I did some deep Google searching & could not find any evidence that necro-mortosis is a real virus. I did however find many links referring to the Zombie World News (a fictional zombie news site) & Max Brooks (a writer of fictional stories). So, I think it’s safe to say that either it doesn’t exist or it’s under such tight security that it might as well not exist. No real reported outbreaks of such virus or similar virus either have been reported or have been allowed to remain on any credible news site.

    Now, if you were to combine effects of AIDS, Typhus, Necrotizing  Fasciculitis & schizophrenia (all major diseases from above) there is a possibility of an individual acting & looking like a zombie from some horror movie (for a very short time until they dropped dead from such debilitating diseases) . Throw in some rabies & you would have a serious biological weapon. Thank God nobody has successfully created anything near that horrifying (although there are some pretty bad diseases out there)

  3. wow!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! i didn’t know how much you could learn on the internet, it,s hard for me to say that people are living with these diseases and nobody is doing anything about it and finding out about it.

  4. I think they should add necro-mortosis and necrosis.For those that don’t know necro mortosis is what you can say is similar to the zombie virus.But luckily a drug as been developed and patients show signs of recovering.

    1. Dear ScienceWiz,

      Polio is a disease that is almost extinct. It does not cause serious disease in most cases, and was not a significant health issue until recently. In the United States, for instance, it only became epidemic after better water practices were put in place, reducing infant exposure to the disease. As such, it did not make the list. Scarlet fever is also serious but has not caused health issues to the degree to make the list.

      All the best,

  5. I just like how malaria is number one, it is estimated that it has already killed half the current human population (not currently though, over a time span of centuries). AIDS wouldn’t even be in the top 5, and heart disease, honestly, not only is this article completely inaccurate, it is a waist of time. Try a new site for better information.



  8. I would also like to say that this helped me tremendously with a science report, a history report, a speech for my reading class,and a speech for my 4h club. Thanks for all your help! Out of all the websites I checked, this was the most specific and detailed. :) So thanks again!

  9. This is a wonderful reference website, I do however ask why Scarlet Fever is not placed here as I thought that it killed over 15 million people in the 1700’s alone. Again I am just a student but please respond!!

  10. Thank you for your honesty. I have bipolar disorder, first misdiagnosed as deep chronic depression. One is no better than the other. My older brother had schizophrenia. I pray that people do not get those illnesses, as well as any of those other ones. While they may be treatable, they are still hellish to live with. Thank you for telling people about all of these. I am certain that it opened many eyes to the possibilities of what can happen to any of us, and to the dire situation that many people in poorer countries must deal with on a daily basis. May God always be with us, and to those like you who bring these things to our attention,

  11. that’s true, i believe that the bubonic plague or what we call the black death is the worst disease that i know in my life that’s why we have prepare

  12. one more thing..I found this blurb when studying the dementia question “HIV does not directly infect the neuron, but the neuron is damaged by the effects of various proinflammatory neurotoxins.” I got it off I think its still safe to say, that in many cases…(HIV)…causes dementia. Last thing, my opinion, but, AIDS is more a label to describe the condition an infected persons immune system after being crippled by the virus, as such AIDS isnt the viral antaganist, and #3 should have been labeled as HIV, not AIDS…interesting thought provoking article though..ignore shd, your matter of fact, unpretentious, yet still informative and compelling style inspired me to spend an hour studying further, wading through, jargon infused articles with a technical descriptions of minute processes…sometimes its just good to hear from a reputable trustworthy source, that this causes that, and thats what your article provided..thanks

  13. Good article..however, in the 2nd paragraph of the AIDSsection you reported 20 million deaths, but at the bottom you reported a death toll of 2 million…also not to be a jerk, but you never said HIV enters can enter the brain and cause dementia…you did however say AIDS did :) Correct me if Im wrong, I was under the impression that AIDS attacks, kills, and destroys the bodies ability to produce helper T cells, making the adaptive immunity system unable to respond to foreign pathogens. As such, people with AIDS die of the flu, or a cold, get weird and varied conditions, and exotic, normally non- deadly afflications that but for having the virus, they would easily survive, if get sick at all.
    Im vaccinated against smallpox…if your wondering..the vaccination process..and i mean process is rough…it pusses up and oozes for 1-2 weeks, and the ooze can cause secondary infection sights that will ooze and puss..nasty..oh, it eventually stops flowing, and scabs over, which then leaves a scar…if you were interested :)
    Also, whats your definition of disease? I hear disease and I think of an invasion of living organisms that behave in ways causing predicatable biological responses in the host…but I see heart disease and schizophrenia..epidemic for sure…seems like labling them diseases make them more sinister, raising awareness so the public will treat them as seriously as they are..kinda like calling it a war on drugs…respectfully, Greg

  14. Dementia is a hereditary condition. Someone suffering from dementia isn’t necessarily infected with HIV. However, dementia may be a symptom of HIV, but just a symptom. When you see dementia patients in a nursing home, it isn’t because they have HIV. Definitely needs to be reworded.
    Otherwise, the article was okay. Could be written better.

    1. There are many causes of dementia. One of them is various neurotoxic effects of the HIV virus – as the post says “In many cases, the disease reaches the brain and causes dementia.” Perhaps the wording could be improved =) Since this follows the line “The symptoms of this disease are confusing and many.” it seems moderately clear that dementia is a common symptom of HIV infection but does not mean that you are HIV infected.

    1. Dear Alex,

      Actually, dementia is caused by HIV. Look into it if you don’t believe me =) The other symptoms are part of the syndrome and the text does not imply that they are directly caused by the HIV virus.

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  16. Excellent article. I recently finished a book about Marburg, and 2 strains of Ebola by Richard Preston called The Hot Zone. I would have loved a shot at a career trying to defeat some of these bugs.

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