When people think of the deadliest diseases in the world, their minds probably jump to the fast-acting, incurable ones that grab headlines from time to time. But in fact, many of these types of diseases don’t rank in the top 10 causes of worldwide deaths. An estimated 56.4 million peopleTrusted Source passed away worldwide in 2015, and 68 percent of them were due to diseases that progressed slowly.
Perhaps even more surprising is that several of the deadliest diseases are partially preventable. Non-preventable factors include where a person lives, access to preventive care, and quality of healthcare. These all factor into risk. But there are still steps everyone can take to lower their risk.
Read on to see the top 10 diseases causing the most deaths worldwide, according to the World Health Organization (WHO)Trusted Source.

The deadliest disease in the world is coronary artery disease (CAD). Also called ischemic heart disease, CAD occurs when the blood vessels that supply blood to the heart become narrowed. Untreated CAD can lead to chest pain, heart failure, and arrhythmias.

Impact of CAD across the world

Although it’s still the leading cause of death, mortality rates have declined in many European countries and in the United States. This may be due to better public health education, access to healthcare, and forms of prevention. However, in many developing nations, mortality rates of CAD are on the rise. An increasing life span, socioeconomic changes, and lifestyle risk factors play a role in this rise.

Risk factors and prevention

Risk factors for CAD include:
  • high blood pressure
  • high cholesterol
  • smoking
  • family history of CAD
  • diabetes
  • being overweight
Talk to your doctor if you have one or more of these risk factors.
You can prevent CAD with medications and by maintaining good heart health. Some steps you can take to decrease your risk include:
  • exercising regularly
  • maintaining a healthy weight
  • eating a balanced diet that’s low in sodium and high in fruits and vegetables
  • avoiding smoking
  • drinking only in moderation

A stroke occurs when an artery in your brain is blocked or leaks. This causes the oxygen-deprived brain cells to begin dying within minutes. During a stroke, you feel sudden numbness and confusion or have trouble walking and seeing. If left untreated, a stroke can cause long-term disability.
In fact, strokes are the leading causeTrusted Source of long-term disabilities. People who receive treatment within 3 hours of having a stroke are less likely to have disabilities. The Centers for Disease Control and Prevention (CDC)Trusted Source reports that 93 percent of people knew sudden numbness on one side was a stroke symptom. But only 38 percent knew all the symptoms that would prompt them to seek emergency care.

Risk factors and prevention

Risk factors for stroke include:
  • high blood pressure
  • family history of stroke
  • smoking, especially when combined with oral contraceptives
  • being African-American
  • being female
Some risk factors of strokes can be reduced with preventative care, medications, and lifestyle changes. In general, good health habits can lower your risk.
Stroke prevention methods may include controlling high blood pressure with medications or surgery. You should also maintain a healthy lifestyle, complete with regular exercise and a healthy diet that’s low in sodium. Avoid smoking, and drink only in moderation, as these activities increase your risk of stroke.

A lower respiratory infection is an infection in your airways and lungs. It can be due to:
Viruses usually cause lower respiratory infections. They can also be caused by bacteria. Coughing is the main symptom of a lower respiratory infection. You may also feel breathlessness, wheezing, and a tight feeling in your chest. Untreated lower respiratory infections can lead to breathing failure and death.

Impact of lower respiratory infections around the world

Risk factors and prevention

Risk factors for lower respiratory infection include:
  • the flu
  • poor air quality or frequent exposure to lung irritants
  • smoking
  • a weak immune system
  • crowded childcare settings, which mainly affects infants
  • asthma
  • HIV
One of the best preventative measures you can take against lower respiratory infections is to get the flu shot every year. People at high risk of pneumonia can also get a vaccine. Wash your hands regularly with soap and water to avoid transmitted bacteria, especially before touching your face and before eating. Stay at home and rest until you feel better if you have a respiratory infection, as rest improves healing.

Chronic obstructive pulmonary disease (COPD) is a long-term, progressive lung disease that makes breathing difficult. Chronic bronchitis and emphysema are types of COPD. In 2004, about 64 million peopleTrusted Source around the world were living with COPD.

Impact of COPD around the world

Risk factors and prevention

Risk factors for COPD include:
  • smoking or secondhand smoke
  • lung irritants like chemical fumes
  • family history, with the AATD gene being linked to COPD
  • history of respiratory infections as a child
There’s no cure for COPD, but its progression can be slowed with medication. The best ways to prevent COPD are to stop smoking and to avoid secondhand smoke and other lung irritants. If you experience any COPD symptoms, getting treatment as soon as possible increases your outlook.

Respiratory cancers include cancers of the trachea, larynx, bronchus, and lungs. The main causes are smoking, secondhand smoke, and environmental toxins. But household pollutions such as fuels and mold also contribute.

Impact of respiratory cancers around the world

A 2015 study reports that respiratory cancer accounts for about 4 million deaths annually. In developing countries, researchers project an 81- to 100-percent increase in respiratory cancers due to pollution and smoking. Many Asian countries, especially India, still use coal for cooking. Solid fuel emissions account for 17 percent of lung cancer deaths in men and 22 percent in women.

Risk factors and prevention

Trachea, bronchus, and lung cancers can affect anyone, but they’re most likely to affect those who have a history of smoking or tobacco use. Other risk factors for these cancers include family history and exposure to environmental factors, such as diesel fumes.
Aside from avoiding fumes and tobacco products, it isn’t known if there’s anything else that can be done to prevent lung cancers. However, early detection can improve your outlook and reduce the symptoms of respiratory cancer.

Diabetes is a group of diseases that affect insulin production and use. In type 1 diabetes, the pancreas can’t produce insulin. The cause isn’t known. In type 2 diabetes, the pancreas doesn’t produce enough insulin, or insulin can’t be used effectively. Type 2 diabetes can be caused by a number of factors, including poor diet, lack of exercise, and being overweight.

Impact of diabetes around the world

People in low- to middle-income countries are more likely to die of complications from diabetes.

Risk factors and prevention

Risk factors for diabetes include:
  • excess body weight
  • high blood pressure
  • older age
  • not exercising regularly
  • an unhealthy diet
While diabetes isn’t always preventable, you can control the severity of symptoms by exercising regularly and maintaining good nutrition. Adding more fiber to your diet can help with controlling your blood sugar.

When you think of Alzheimer’s disease or dementia, you might think of a loss of memory, but you might not think of a loss of life. Alzheimer’s disease is a progressive disease that destroys memory and interrupts normal mental functions. These include thinking, reasoning, and typical behavior.
Alzheimer’s disease is the most common type of dementia — 60 to 80 percent of dementia cases are in fact Alzheimer’s. The disease starts off by causing mild memory problems, difficulty recalling information, and slips in recollection. Over time, however, the disease progresses and you may not have memory of large periods of time. A 2014 study found that the number of deaths in the United States due to Alzheimer’s may be higher than reported.

Risk factors and prevention

Risk factors for Alzheimer’s disease include:
  • being older than 65
  • a family history of the disease
  • inheriting genes for the disease from your parents
  • existing mild cognitive impairment
  • Down syndrome
  • unhealthy lifestyle
  • being female
  • previous head trauma
  • being shut off from a community or having poor engagement with other people for extended periods of time
There’s not currently a way to prevent Alzheimer’s disease. Researches aren’t clear why some people develop it and others don’t. As they work to understand this, they’re also working to find preventive techniques.
One thing that may be helpful in reducing your risk of the disease is a heart-healthy diet. A diet that’s high in fruits and vegetables, low in saturated fats from meat and dairy, and high in sources of good fats like nuts, olive oil, and lean fish may help you reduce your risk of more than just heart disease — they may protect your brain from Alzheimer’s disease, too.

Diarrhea is when you pass three or more loose stools in a day. If your diarrhea lasts more than a few days, your body loses too much water and salt. This causes dehydration, which can lead to death. Diarrhea is usually caused by an intestinal virus or bacteria transmitted through contaminated water or food. It’s particularly widespread in developing nations with poor sanitary conditions.

Impact of diarrheal diseases around the world

Diarrheal disease is the second top causeTrusted Source of death in children younger than 5 years. About 760,000 children die from diarrheal diseases each year.

Risk factors and prevention

Risk factors for diarrheal diseases include:
  • living in an area with poor sanitary conditions
  • no access to clean water
  • age, with children being the most likely to experience severe symptoms of diarrheal diseases
  • malnourishment
  • a weakened immune system
According to UNICEF, the best method of prevention is practicing good hygiene. Good handwashing techniques can reduce the incidence of diarrheal diseases by 40 percent. Improved sanitization and water quality as well as access to early medical intervention can also help prevent diarrheal diseases.

Tuberculosis (TB) is a lung condition caused by bacteria called Mycobacterium tuberculosis. It’s a treatable airborne bacterium, although some strains are resistant to conventional treatments. TB is one of the top causes of death in people who have HIV. About 35 percentTrusted Source of HIV-related deaths are due to TB.

Impact of TB around the world

The cases of TB have fallen 1.5 percentTrusted Source each year since 2000. The goal is to end TB by 2030.

Risk factors and prevention

Risk factors for tuberculosis include:
  • diabetes
  • HIV infection
  • a lower body weight
  • proximity to others with TB
  • regular use of certain medications like corticosteroids or drugs that suppress the immune system
The best prevention against TB is to get the bacillus Calmette-Guerin (BCG) vaccine. This is commonly given to children. If you think you’ve been exposed to TB bacteria, you can start taking a treatment medication called chemoprophylaxis to reduce the likelihood of developing the condition.

Cirrhosis is the result of chronic or long-term scarring and damage to the liver. The damage may be the result of a kidney disease, or it can be caused by conditions like hepatitis and chronic alcoholism. A healthy liver filters harmful substances from your blood and sends healthy blood into your body. As substances damage the liver, scar tissue forms. As more scar tissue forms, the liver has to work harder to function properly. Ultimately, the liver may stop working.

Risk factors and prevention

Risk factors for cirrhosis include:
  • chronic alcohol use
  • fat accumulation around the liver (nonalcoholic fatty liver disease)
  • chronic viral hepatitis
Stay away from the behaviors that can lead to liver damage to help prevent cirrhosis. Long-term alcohol use and abuse is one of the leading causes of cirrhosis, so avoiding alcohol can help you prevent damage. Likewise, you can avoid nonalcoholic fatty liver disease by eating a diet that’s healthy, rich in fruits and vegetables, and low in sugar and fat. Lastly, you can reduce the likelihood of contracting viral hepatitis by using protection during sex and by avoiding sharing anything that could have traces of blood. This includes needles, razors, toothbrushes, and more.

While deaths from some diseases have increased, those from more serious conditions have also decreased. Some factors, such as an increasing life span, naturally increase the incidence of diseases such as CAD, stroke, and heart disease. But many of the diseases on this list are preventable and treatable. As medicine continues to advance and prevention education grows, we may see a reduction in death rates from these diseases.
A good approach to lowering your risk of any of these conditions is to live a healthy lifestyle with good nutrition and exercise. Avoiding smoking and drinking in moderation can also help. For bacterial or viral infections, proper handwashing can help prevent or reduce your risk.