Heart disease, stroke, and respiratory infections are among the leading causes of death globally each year. Fortunately, there are preventive measures that can help reduce the risk of developing these conditions.
An estimated 55.4 million people passed away worldwide in 2019, and 74% of these deaths were because of noncommunicable diseases, or chronic conditions that progress slowly.
While many people associate the world’s deadliest diseases with sudden, high-profile outbreaks of rare or incurable illnesses, these are not the primary causes of death worldwide. In reality, the most fatal diseases tend to be chronic conditions that develop over time and are often preventable.
while rare, fast-acting diseases like Ebola or certain pandemics may dominate headlines due to their dramatic and immediate impact, the deadliest diseases globally tend to be chronic, long-term conditions. According to the World Health Organization (WHO), the top causes of death worldwide are mostly non-communicable diseases (NCDs) that develop slowly over time and are often preventable.
Top Global Causes of Death (Based on WHO Data)
1. Heart Disease (Coronary Artery Disease)
Coronary artery disease (CAD), also known as ischemic heart disease, is the world’s deadliest disease. It occurs when the blood vessels that deliver oxygen-rich blood to the heart become narrowed or blocked. If left untreated, CAD can cause chest pain, irregular heartbeats, and even heart failure.
Globally, CAD remains the leading cause of death, though mortality rates have dropped in many European countries and the United States, likely due to improved healthcare access, public health initiatives, and preventive measures. In contrast, developing countries are experiencing rising death rates from CAD, driven by longer lifespans, lifestyle changes, and socioeconomic factors.
2. Stroke
A stroke happens when a blood vessel in the brain becomes blocked or bursts, cutting off the supply of oxygen to brain cells. Without oxygen, these cells begin to die within minutes, making stroke a medical emergency. Common signs of a stroke include sudden numbness or weakness—especially on one side of the body—confusion, difficulty walking, and problems with vision. If not treated quickly, a stroke can lead to lasting disabilities.
3. Chronic Obstructive Pulmonary Disease (COPD)
Chronic obstructive pulmonary disease (COPD) is a progressive, long-term lung condition that makes breathing increasingly difficult. It includes conditions like chronic bronchitis and emphysema. In 2018, around 16.4 million people in the United States reported being diagnosed with some form of COPD. The main risk factors include smoking or exposure to secondhand smoke, inhaling lung irritants such as chemical fumes, a family history of COPD—particularly linked to the alpha-1 antitrypsin deficiency gene—and having a history of respiratory infections during childhood. While there is no cure for COPD, medications can help slow its progression and improve quality of life.
4. Lower Respiratory Infections
Lower respiratory infections affect the lungs and airways, and are commonly caused by viruses—though bacteria can also be responsible. Conditions such as influenza (flu), pneumonia, bronchitis, and tuberculosis (TB) fall into this category. A persistent cough is the most common symptom, often accompanied by chest tightness, wheezing, shortness of breath, and sometimes fever, chills, or sweating. In some cases, the cough may produce sputum that contains blood.
5. Neonatal Conditions
Neonatal conditions refer to health issues that affect newborns during the first 28 days of life—a critical period for survival and development. These conditions can include premature birth, low birth weight, birth asphyxia, infections (like sepsis and pneumonia), and congenital abnormalities. Many of these problems arise due to complications during pregnancy, delivery, or the immediate postnatal period. In low- and middle-income countries, limited access to skilled care, clean environments, and essential medicines makes newborns especially vulnerable. However, many neonatal conditions are preventable and treatable through proper prenatal care, skilled birth attendance, timely vaccinations, and early detection. Improving neonatal health is key to reducing infant mortality and ensuring a healthy start to life.
6. Trachea, Bronchus, and Lung Cancers
Respiratory cancers, which include cancers of the trachea, larynx, bronchi, and lungs, are among the most serious health threats globally. The primary causes are smoking, exposure to secondhand smoke, and environmental pollutants such as industrial toxins and diesel fumes. In many developing countries, especially in parts of Asia, the continued use of coal and other solid fuels for cooking significantly increases the risk, particularly among women. These indoor pollutants contribute to a large percentage of lung cancer deaths—up to 22% in females. While anyone can develop respiratory cancer, those with a history of smoking or prolonged exposure to toxic air are at higher risk. Although complete prevention is not always possible, avoiding tobacco, improving indoor air quality, and undergoing regular screenings can greatly reduce risk and lead to earlier, more effective treatment.
7. Alzheimer’s Disease and Other Dementias
Alzheimer’s disease is a progressive brain disorder that gradually affects a person’s memory, thinking, and reasoning abilities. It slowly disrupts everyday mental functions, such as making decisions, recalling information, and performing familiar tasks.
As the most common form of dementia, Alzheimer’s accounts for 60 to 70% of all dementia cases.
In the early stages, it may show up as occasional forgetfulness or difficulty remembering recent conversations. But as the disease advances, memory loss becomes more severe—eventually leading to gaps in recollection that span entire periods of life.
8. Diabetes Mellitus
Diabetes Mellitus is a chronic condition where the body is unable to properly regulate blood sugar (glucose) levels. It occurs either because the body doesn’t produce enough insulin or can’t use insulin effectively.
Insulin is a hormone made by the pancreas that helps glucose enter the cells for energy. Without enough insulin, glucose builds up in the bloodstream.
9.Dehydration due to diarrheal diseases
Diarrheal diseases are a leading cause of dehydration, especially in children and the elderly. When someone experiences diarrhea, their body loses large amounts of water and electrolytes (like sodium, potassium, and chloride) through frequent, watery stools. If this fluid loss is not replaced quickly, it can lead to dehydration, which may become severe and life-threatening.
10. Tuberculosis
Tuberculosis is a bacterial infection caused by Mycobacterium tuberculosis. It mainly affects the lungs (pulmonary TB) but can also impact other parts of the body such as the brain, kidneys, spine, and lymph nodes (extrapulmonary TB).
TB spreads through the air when an infected person coughs, sneezes, or talks. It is a serious but curable and preventable disease.
11. Cirrhosis
Cirrhosis is a chronic liver disease where healthy liver tissue is replaced by scar tissue (fibrosis). This scarring prevents the liver from working properly and worsens over time. It’s often the result of long-term liver damage.
