Chilling Facts About the World’s Most Fatal Diseases

Lung Cancer This is one of the world’s most deadly diseases but also one of the most avoidable. Lung cancer has a higher mortality rate than… Darren Ryding - February 25, 2024

Medical advances mean that the world’s most fatal diseases no longer impact developed countries like before. However, they’re still out there and afflict many populations across the globe. That’s why it’s crucial to be aware of them because we never know when they’ll strike.

Let’s look at some chilling facts about the world’s most fatal diseases. Some of these conditions are very common like malaria and influenza but can still be lethal. Others are more obscure but this makes them even deadlier. Check out these disturbing illnesses below and their scariest traits.

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BMJ Case Reports

Stoneman Syndrome

This is one of the most unusual conditions on this list because it only afflicts about 800 people in the world. In short, it causes the body’s fibrous tissues to solidify and turn into bone. Finally, the body is like a statue because it becomes very difficult and painful to move.

It’s a prepubescent condition that develops and spreads over time. Eventually, it renders sufferers immobile, deaf, and incapable of eating without help. There’s no cure for this horrifying disease and it destroys the overall quality of life. Luckily it’s rare because it’s like something from a science-fiction movie. (via Vinmec)

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It may be shocking to learn that diabetes is one of the world’s most fatal diseases. Most people dismiss it because insulin allows patients to enjoy a high quality of life. One of the most horrifying facts about diabetes is that it’s a leading cause of lower body amputation.

Sufferers may have ulcers and wounds in their feet that don’t heal properly because of high blood pressure. It’s crucial to treat these issues early and to stop smoking to ensure the best chance of keeping limbs. Diabetes also commonly kills through heart attacks and strokes in the U.S. (via Health Match)

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Philanthropy Journal


A horror movie director couldn’t come up with a scarier premise than HGPS or progeria. This childhood condition causes youngsters to age rapidly. Some people call it ‘Benjamin Button Disease’ because of its effect on children. A rare mutation triggers rapid aging with a bunch of dramatic symptoms.

Firstly, there’s the physical impact on the child because they’ll develop wrinkled skin and visible veins. They may also have a larger head and protruding ears. Usually, progeria causes heart disease that ultimately seals their fate. Luckily, it only afflicts one in four million people across the planet (via Medscape).

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Lung Cancer

This is one of the world’s most deadly diseases but also one of the most avoidable. Lung cancer has a higher mortality rate than any other common cancer type. It only has a five-year survival rate of 23 percent in the U.S. Early treatment is crucial because this condition is almost always fatal when it progresses. The easiest way to avoid lung cancer is to quit smoking. Let’s be honest; it’s one of the dumbest and most selfish habits a person can have

Worldwide, about 17 percent of lung cancer sufferers are non-smokers. According to the CDC: “Lung cancer also can be caused by using other types of tobacco (such as pipes or cigars), breathing secondhand smoke, being exposed to substances such as asbestos or radon at home or work, having certain gene mutations (unusual changes made when your body’s cells are dividing), or having a family history of lung cancer.” (via Yale Medicine).

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Kuru Disease

There are two ways of looking at the world’s most fatal diseases. There are common illnesses that kill the most people across the planet. Then there are obscure conditions like Kuru Disease with 100 percent fatality rates. This one came from Papua New Guinea as a result of cannibalism.

Common Kuru symptoms include uncontrollable laughing and shivering. It can develop after eating human brain tissue with the last known case in 2005. In sum, Kuru Disease destroys the brain and nervous system. Don’t eat people is probably the best advice we can give (via NPR).

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Alzheimer’s Disease

This is one of the world’s most tragic illnesses because it affects so many people. Alzheimer’s Disease is a degenerative condition that eventually destroys a patient’s quality of life. Many family members think that the scariest moment is when the sufferer forgets their relationship to them.

It’s so cruel and eventually their entire personality might change. Another terrifying symptom of Alzheimer’s Disease is when the person loses a sense of their surroundings and wanders. Technically, Alzheimer’s isn’t fatal but it does trigger a general decline that will prove deadly (via AJC).



It may shock people to learn that stroke mortality rates are on the rise. Two types of strokes kill in equally nasty ways. The first is an ischemic stroke that blocks the blood flow to the brain. Meanwhile, hemorrhagic strokes occur when blood vessels burst. A transient ischemic attack (TIA), often called a “mini-stroke,” is frequently overlooked by people, with only 3 percent seeking medical care.

New Jersey State University discovered that strokes have been on the rise over the past four decades. This is one of the most disturbing facts about these conditions because they shouldn’t be. However, poor diets and lifestyle choices mean that the risk has never been higher. Read this article for signs and precursors to a mini-stroke. (via IMJ).

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Brown Emergency Medicine

Necrotizing Fasciitis

This condition has a nickname that tells us everything we need to know about it: ‘Flesh-Eating Disease.” Nobody wants a doctor to tell them that they have this because it’s almost always fatal. Luckily there are usually fewer than 1,000 cases per year in the United States.

Bacteria enter the body through breaks in the skin like cuts and scrapes. The flesh dies away and can’t replace itself properly leaving horrific, graphic damage. It’s one of the world’s most fatal diseases with a very high mortality rate. Symptoms include ulcers, diarrhea, and dizziness. (via Springer Link)

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Modern medical advances eliminated smallpox in developed countries. This is just as well because it’s one of the world’s most fatal diseases with a 30 percent mortality rate. It also horrifically scars victims and leaves them carrying the marks of the condition.

Historically, smallpox had a lethal impact on global society. It wreaked havoc across indigenous South American communities and ravaged Europe. Meanwhile, it causes permanent blindness in one-third of victims. Smallpox is no joke because it’s horrific (via

All That’s Interesting.

Harlequin Disease

This is a rare skin disease that has a crazy impact on young victims. Babies have thick, hardened skin that resembles plates. Only one in half a million people have this condition and it’s very severe. One of the most horrible results is that they can’t close their eyes.

Skin infections can cause serious problems for Harlequin patients and they require lifelong care. In severe cases, they can’t function properly because their skin is too tight. Maybe it constricts their chest, stops them from breathing, or prevents them from eating (via First Skin Foundation).

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It may shock people to learn that Tuberculosis cases are on the rise again. The main reason behind this is that some parents are neglecting to vaccinate their children. Unfortunately, the side-effect is this contagious disease is spreading. It seriously damages the lungs and has a high fatality rate .

This is an airborne disease so it’s difficult to control it. People with HIV have a stronger chance of contracting tuberculosis than usual. It preys on victims with vulnerable immune systems so it’s important to know the risks. Luckily, it’s treatable but don’t leave it too late. (via WHO)

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Bubonic Plague

It will shock many people to learn that the Bubonic Plague still exists. This is one of those diseases that we should have eradicated long ago. Most folks associate it with the Black Death, an epidemic that wiped out up to half of medieval Europe’s population .

Central Asia, Africa, South America, and even the U.S. experienced plague cases over the past couple of decades. It’s always fatal if victims don’t receive immediate medical attention. Typically, rodents host plague-carrying fleas that spread this horrible disease. (via American Scientist)


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Diarrhoeal Disease

Most people don’t think of diarrhea as a lethal condition. However, it’s one of the world’s most fatal diseases and the second leading cause of death in children under five. This is a shocking statistic that shows its impact across the globe. Usually, they have diarrhea because they drink dirty water.

Severe dehydration is the main cause of death. They lose electrolytes and can’t retain fluids in their body. It’s a horrible way to go but it is very avoidable if they get treatment. Unfortunately, many communities don’t have the same access to modern medicine (via WHO).

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Here’s another of the world’s most fatal diseases. Wild animals spread this disease with several outbreaks across West Africa. The only way it spreads is through direct contact with bodily fluids. Some people think that it is an airborne condition but that’s not true.

That’s why it’s not effective to close borders to countries with Ebola outbreaks. Ebola has a 50 percent death rate so it’s incredibly dangerous. Symptoms include severe fevers and diarrhea. These days there are vaccines but they’re not effective against all strains and have mixed results (via Al Jazeera).

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Health Hub


Many people don’t think of AIDS as a problem now in Western society. That’s an amazing sign of progress but there are still some cold, hard facts. It continues to ravage communities across the globe. AIDS develops from untreated HIV and has a brutal effect on the immune system

Usually, another disease provides the finishing blow after AIDS compromises the immune system. Sufferers waste away because it’s one of the world’s most fatal diseases. Luckily, these days some medications help people live full lives with HIV and prevent them from contracting the deadly variant. (via The Body).

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Everybody knows measles because most people receive vaccinations when they are young. Some frightening complications occur from untreated measles. Victims can suffer blindness and pneumonia. They may even die from breathing issues and brain problems.

Adults over the age of 20 face higher risks than children. However, infants also can experience more severe symptoms. Experts unanimously agree that the best way to prevent an outbreak is to get vaccinations. This creates hive immunity and keeps everyone safe (via Unity Point).

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Creutzfeldt-Jakob disease

Many mistake CJD for Mad Cow Disease or compare it to Alzheimer’s. It indeed shares symptoms with the latter but it’s much more severe. CJD patients usually only live for a year after diagnosis. They receive all of the common signs of Alzheimer’s but more intensely. It’s also contagious through cross-contamination.

CJD only afflicts about one in four million people and there’s no cure. Doctors focus on palliative care because there’s nothing else they can do except comfort the patient. The only positive thing is that it doesn’t last for very long. However, it’s one of the world’s most fatal diseases because of its rapid, lethal impact. (via NBC News)

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Malaria is the third most lethal disease for infants in the world. The mosquito-borne condition kills an equivalent of 800 children per day. Most of these occur in Sub-Saharan Africa where there’s little access to vaccines. Pregnant women and young children are the most vulnerable.

Symptoms include a yellowing of the skin and fever. Victims suffer attacks that can be very frightening and painful. Malaria isn’t always fatal but it does have a disproportionate impact on marginalised communities. This is true of many of the world’s most fatal diseases (via UNICEF).

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Lesch-Nyhan Syndrome

This is a horrible but rare disease that overwhelmingly afflicts young males. Unfortunately, the prognosis is poor because they usually don’t live beyond 20 years old. Furthermore, they have a traumatic life, both for themselves and their loved ones because this is an awful condition.

Overproduction of uric acid causes kidney problems. They also suffer severe neurological issues that may cause them to uncontrollably bite their nails or bang their heads. This is very distressing for family members because it’s a compulsive behavior that they can’t control (via Verywell Health).

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Raising Children Network


Many people don’t take influenza seriously but they should. It is one of the world’s most fatal diseases and it is very disturbing. Flu virus strains mutate more in a day than human have in their entire existence. Meanwhile, they’re incredibly durable and can live on hard surfaces for 48 hours.

Usually, bacterial influenza causes fatalities with hundreds of thousands of deaths per year. One-fifth of women’s handbags contain more bacteria than a toilet seat. This shows how important it is to wash hands regularly. Influenza can progress into pneumonia which is more serious (via Medical Academic).

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The liver is one of the body’s most important organs. However, many people don’t realize that they may be living with fatty liver disease, a silent killer. Cirrhosis is the worst version of this because it’s incurable. If the patient doesn’t seek medical attention they won’t survive.

Cirrhosis results in jaundice so the skin and eyes will turn yellow. They’ll also suffer from bloating and itchy skin. A liver transplant may be the only way to deal with cirrhosis because it replaces the damaged organ. Poor quality of life is the biggest cause of cirrhosis (via Medical News Today).

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Sleeping Sickness

This is another insect-borne disease with potentially deadly results. Tsetse flies carry this nasty condition that will be lethal if untreated. The first sign is a red sore that may be painful. But this develops into more symptoms including swollen lymph nodes and aching joints.

Doctors may need to perform lumbar punctures for several years as they treat this condition. It almost always requires hospitalization and there’s no vaccine. This is one of the world’s most fatal diseases because it disproportionally impacts marginalized African communities (via John Hopkins Medicine).



This is one of the world’s most terrifying diseases and remains a risk in many countries. Usually, domestic dogs transmit this zoonotic disease through a bite. It’s crucial to receive the vaccine as quickly as possible. That’s because the clinical symptoms have an overwhelming fatality rate.

One of the most shocking symptoms of rabies is hydrophilia. This is when the body rejects water and causes the patient to convulse uncontrollably. Meanwhile, they may experience hallucinations and excess energy. It’s a horrible condition but luckily it’s avoidable if they have access to the vaccine (via Cleveland Clinic).

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Cholera is one of the world’s most fatal diseases and can even kill healthy people quickly. This condition almost always occurs after drinking contaminated water. It infects the intestine and produces severe symptoms that ruthlessly take hold. In 2024, there was a deadly outbreak in Zambia that killed hundreds.

This is why communities must have access to clean drinking water. Otherwise, they risk the contraction of this potentially lethal disease. Cholera also develops in areas that lose access to key infrastructure. Usually, they die from diarrhea and dehydration (via AP News).

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Only My Health

Heart Disease

Heart disease, reigning as the foremost cause of mortality globally, casts a chilling shadow over public health landscapes. Its dominance in the realm of fatalities underscores a sobering reality: the insidious threat it poses to lives worldwide. With each heartbeat, individuals confront the specter of potential cardiac failure, an ever-present reminder of mortality’s fragility.

Unyielding and indiscriminate, heart disease transcends demographic boundaries, claiming victims regardless of age, gender, or background. Year after year, its toll mounts, leaving families shattered and communities reeling. The narrative of heart disease is one of stark statistics and somber realities, underscoring the urgent need for collective action to confront this pervasive killer. (via Premier Heart & Vein Care).