Top 10 Deadliest Diseases

Our human history is stained with the blood of the people who were killed in the war. However, the human diseases are the world’s biggest killers because they don’t discriminate race. In this post, let’s find out the top 10 deadliest diseases in the world. 

1. Ebola
It’s a rare but deadly disease. An Ebola virus causes Ebola. It can infect humans and primates. The first case was discovered in 1976 in the Democratic Republic of the Congo. Since then, the disease spread sporadically in Africa. 

The natural reservoir host of the virus is still unknown, but researchers believe that it’s animal-borne, and the most likely reservoir are the bats. 

It requires direct contact with blood and body fluids, objects, and infected primates to get the virus. The outbreak in 2014 was considered to be the largest and most complex since the discovery of the disease in 1976. 

The said outbreak was so bad that all flights to those affected countries had been restricted. Health experts used experimental vaccines before they’ve tried on humans. Because of how it infects people, it strikes fear in people worldwide. 

The infection starts as an ordinary infection with common symptoms, such as sore throats, fever, and headaches. If it’s left untreated, it targets the person’s immune system causing blood vessels to explode. It’ll then result in internal and external bleeding. 

But Ebola isn't the only deadly disease in the world. 

2. The Black Death

The plague began in 1347 when 12 of the trading ships returned from a journey to the Black Sea. It ravaged communities in Europe and changed their economy. Then, it spread to the north and east and affected Scandinavia and Russia. 

It spread from animals to humans through fleas from dying rats. When it infects human, the bacteria suppresses vital organs of the patient. 

Contrary to what others believed, the Black Death wasn’t a disease of poverty. Many wealthy individuals across Europe lost more than half of their members. Some of them became extinct. 

The symptoms included swellings in the groin, neck, and armpits. It also caused dark patches. Patients also experienced coughing of blood. 

Medieval people didn't understand the disease. For them, it came from God. As a result, they responded it with prayers and processions. Modern antibiotics could have combatted the plague. However, there were threats from mutating diseases and becoming immune to the effects of antibiotics. 

When the disease subsided in the 1350s, it already killed 60 percent of the European population. Per year, it still affects up to 2,000 people. Most of the cases are in sub-Saharan Africa. 

3. Smallpox

Although smallpox has already been eradicated worldwide because of a global immunization campaign, this disease was once a deadly disease that affected the human population for thousands of years. 

For research purposes, samples of the virus are kept. But it has led to concerns that this disease could be used as a biological warfare agent. 

Even if the illness has been eradicated, there’s still no cure for it. There’s a vaccine that can prevent it. However, the risks of the side effects are too high to give it as a routine vaccination for people who are at low risk of exposure to the virus. 

After you’ve infected, the symptoms will only appear within 12 to 14 days. During the incubation period, you’ll look healthy. But you can’t infect others yet. After that period, however, you’ll develop symptoms, like fever, headache, severe back pain, fatigue, and vomiting. 

A few days later, you’ll develop red spot appearing on your face, forearms and your trunk. This infection is caused by the variola virus, which can be transmitted from person to person or via contaminated items. 


The HIV/AIDS epidemic appeared out of thin air. It was first reported in a Morbidity and Mortality Weekly Report. The report said that five young healthy gay men from LA were suffering from a lung infection. 

But, within a few days, doctors from New York, San Francisco and other parts of the US called the CDC to report about similar cases. By the end of 1981, the CDC reported 270 cases of gay men with severe immune deficiency. Out of 270 cases, 121 of them died. 

At that time, scientists weren't sure what infecting these healthy gay men. So, gays were discriminated against. Every day, more cases were reported. It was in 1982 that the CDC first used the word AIDS. 

In the next few years, HIV/AIDS organizations were growing to find the mode of transmission and know more about how to fight it. Since then, scientists discovered that the disease was transmitted through bodily fluids. 

There’s still no cure yet for HIV/AIDS. However, some drugs can help in managing the disease. There are 75 million people with HIV worldwide. And 36 million of them died. In 2012 alone, 1.6 million people died of this disease. 

Before, this disease was considered a death sentence. But it’s no longer the case today because there are medicines that allow patients to live normal, healthy lives. 

5. Yellow Fever

It’s an acute viral hemorrhagic disease. Mosquitoes transmit yellow fever. The yellow in the name represents jaundice affecting some patients. The symptoms will include fever, jaundice, nausea, vomiting, and fatigue. When a patient is infected with the virus, you’ll develop severe symptoms. Half of those patients died within 7 to 10 days. 

This disease isn't common in the US, but it’s endemic in Africa, Central, and South America. In 2006, the Yellow Fever Initiative was launched. Since then, there’s significant progress in fighting against the disease in West Africa. More than 105 million people in this area were vaccinated. During 2015, there were no reports of outbreaks of yellow fever. 

A vaccine can prevent yellow fever. The good thing is that it’s safe and affordable. A single dose of vaccine can offer long-term protection against the disease. That said, a booster isn't needed. 

Furthermore, survival rates can be increased through a proper supportive treatment in hospitals. Currently, there’s no anti-drug for this disease. 

6. Tuberculosis

It’s an infectious disease that affects the lungs. In 2012, the CDC reported that 1.3 million died from this disease. And 8.6 million are falling ill. 

The causative agent of TB is Mycobacterium tuberculosis. It’s spread through the air when an infected person coughs, spits, laughs and talks. 

Even though it’s contagious, you can’t easily catch the bacteria. Patients with this condition who received appropriate treatment for two weeks are no longer considered as contagious. 

What’s more terrifying is that some strains of the bacterium have become resistant to drugs. 

7. Cholera

It’s another deadly infectious disease that causes patients to experience severe watery diarrhea. If it’s left untreated, it can lead to dehydration and death. The primary cause of this disease is eating food or drinking water contaminated with Vibrio cholerae. 

This disease was once prevalent in the US in the 1800s. It was before modern sewage treatment systems eradicated the spread of contaminated water. Because of the current treatment system, only 10 cases of this disease are reported in the US each year. And half of those cases are obtained abroad. 

8. Malaria
It was first identified in 1880. At that time, scientists considered this disease as a result of a parasitic infection. Malaria was taken from an Italian word malaria, which means bad air. This disease is transmitted to humans via infected mosquitoes. These mosquitoes are mostly active at dusk and dawn. 

In 2013, an estimated 198 millions cases of this disease were reported, and 584,000 of them are dead. This disease occurs mostly in subtropical and poor areas of the world, like the Philippines. Although malaria has been eliminated from the US in the 1950s, the mosquitoes that carry it remain. That is, it can still be a risk of reintroduction. 

9. Spanish Flu

The Spanish flu pandemic in 1918 to 1919 was the deadliest in modern history. It infected 500 million people in the world. During the pandemic, there were 675,000 Americans who died. It was first observed in Europe, the US and some countries in Asia before it spread around the world. 

Most of the flu victims were young, healthy adults. At that time, effective drugs and vaccines were nowhere to be found. 

It was only in 1919 that the pandemic came to an end. 

10. Meningitis

It’s a rare infection affecting the delicate membranes covering the brain and spinal cord. For bacterial meningitis, this disease can be deadly. It’s also contagious. Viral meningitis, on the other, is less severe. Most patients can easily recover without specific therapy. Fungal meningitis is also rare, and it only affects patients with weakened immune systems. 

Meningitis is caused by bacteria, virus or fungi. Among the three types of meningitis, the most serious is bacterial meningitis that requires immediate medical attention. It’s also the type that’s deadly. A patient can die within hours. If not, he’ll suffer from permanent damage to the brain.


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