What Are The 10 Most Common Diseases? What Are The 10 Most Common Diseases?

The World’s Deadliest Diseases

To answer the question of what are the 10 most common diseases in the world, really takes more information than the question gives us. To answer the question of what are the world’s 10 deadliest diseases, while not necessarily pleasant, is a specific enough question to provide quantitative information for.

Many people in the U.S. and from other industrialized countries would probably be able to accurately guess what some of the 10 deadliest diseases in the world are but they will likely be surprised by the answers for others. An oftentimes surprising fact for many is that several of the deadliest diseases are partially preventable and/or easily managed but many people in the world do not have access to quality healthcare and resources that could keep these diseases under control and not a life-threat.

10 Deadliest Diseases

According to the World Health Organization (WHO) the following are the 10 diseases that cause the most deaths worldwide:

Alzheirmer’s and Other Dementias

Alzheimer’s disease was the cause of 2.7% of deaths Worldwide in 2015. Alzheimer’s disease is a progressive disease that destroys memory and interrupts normal mental functions. Without full-time monitoring and care, Patients with severe to moderate Alzheimer’s cannot typically survive on their own, and even with good full-time care, severe Alzheimer’s patients’ physical bodies often decline rapidly.

Chronic Obstructive Pulmonary Disease (COPD)

COPD caused 5.6% of deaths worldwide from 2000 to 2015. ICOPD is long-term, progressive lung disease that makes it difficult to breath. There’s no cure for COPD but its progression can be slowed with medication and the sooner a patient gets treatment the more favorable is their outcomes.


Cirrhosis is the cause of 2.1% of worldwide deaths. It is the result of chronic or long-term scarring and damage to the liver from a variety of causes. Most common conditions that cause cirrhosis include but are not limited to, kidney disease, hepatitis and alcoholism.  

Diarrheal Diseases

Dehydration from diarrheal diseases causes 2.5% of deaths worldwide. When someone suffers from a virus or bacteria that causes diarrhea for more than a few days, their body can become dangerously depleted of water and salt. When this is not corrected, a person can die.

Ischemic Heart Disease / Coronary Artery Disease

Causing 15.5% of deaths worldwide, Ischemic heart disease, also referred to as coronary artery disease (CAD) is considered to be the deadliest disease in the world. It occurs when the blood vessels that supply blood to the heart become narrowed.

Lower Respiratory Infections

Lower respiratory infections cause 5.7% of deaths worldwide. A lower respiratory infection is an infection in your airways and/or lungs.


Strokes cause over 11.1% of deaths worldwide. A stroke occurs when an artery to your brain becomes blocked or when an artery leaks.

Respiratory Cancers

Trachea, bronchus and lung cancers, often referred to as respiratory cancers are the cause of 3% of the deaths in the world. 


Although tuberculosis was under control in the United States until more recent decades, it is still the cause of 2.4 of the deaths in the world per year.

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