7 Most Deadly Diseases In The World & How To Prevent Them

You probably think of the fast acting diseases as the most deadliest ones. Surprisingly, many of such diseases don’t run in the top 10 lists. In fact, most of the deadly diseases are those that have slow progression and relatively high prevalence. World Health Organization (WHO) has provided a list of such diseases. Their list is based on the number of global cause-specific deaths that occurred in the year 2015. As per an estimate, 56.4 million people died in that year out of which 68% deaths were due to slowly progressing diseases.

Although there are certain risk factors such as age, gender, and genetics that we have no control over, most of the other risk factors for these deadly diseases are modifiable. Hence, we can significantly reduce our risk of getting these diseases. Read on to find out about the top 7 diseases causing most of the global deaths.

7 Most Deadly Diseases In The World & How To Prevent Them

Top 7 deadliest diseases in the world P.S. how to prevent them

1. Ischemic heart disease is the first most deadly disease in the world.

Ischemic heart disease is a term used for heart illness caused by the narrowing of arteries supplying blood to the heart. When arteries get narrowed, heart muscles receive less blood supply and hence inadequate oxygen which can ultimately lead to heart attack.

Ischemic heart disease is also known as coronary artery disease (CAD) and coronary heart disease (CHD). 8.8 million deaths resulted from CAD in the year 2015. This accounts for 15.5% of the total deaths in that year making CAD the number one cause of global deaths.

Certain risk factors make a person more prone to this deadliest disease. However, there are also specific prevention strategies that you can apply to lower your risk of getting CAD. Let’s see what are those strategies.

Risk factors

It’s good to know about the risk factors as some of them are modifiable. In the case of ischemic heart disease, the controllable risk factors include:

  • High cholesterol level
  • Hypertension
  • Prediabetes
  • Diabetes
  • Smoking
  • Sedentary lifestyle
  • Malnutrition (unhealthy diet)
  • Obesity
  • Stress
  • Excessive use of alcohol

Gender, age, and family history are the risk factors that you cannot control. Most individuals have at least one of these given risk factors, but your risk increases as the number of risk factors increase. Moreover, some risk factors are high in intensity as they put you at a higher risk of catching the disease, e.g., smoking and high cholesterol.

Prevention strategies

Adopting some heart-healthy lifestyle changes can go a long way in protecting you against heart diseases. The best part is that controlling one risk factor may also control several other risk factors. For example, losing weight will also lower the blood pressure and control diabetes.

  • Lifestyle changes
  • Eat a healthy and balanced diet
  • Physical activity
  • Aim for a healthy weight
  • Reduce stress
  • Regular exercise
  • Quit smoking (at least try)
  • Watch your alcohol intake (no more than 14 units a week)

2. Stroke is the second most deadly disease in the world.

Around 6.2 million deaths in 2015 were attributed to stroke. This number constitutes 11.1% of the global deaths in that year.

A stroke occurs due to a blocked or leaked artery in the brain. This blockade or leakage results in lack of oxygen supply in that area and deprived brain cells begin to die soon.

An instant result of a stroke is sudden numbness of the limbs, confusion, troubles speaking, and partial vision impairment. Leaving it untreated will lead to long-term disability.

If someone asks you about the leading cause of long-term disability worldwide, your answer should be the stroke.

Risk factors

Just like the case with multiple other diseases, many factors increase the chances of having a stroke. Again, some are controllable while others are not. Modifiable risk factors for stroke include:

  • high blood pressure
  • smoking
  • high blood cholesterol
  • diabetes
  • obesity
  • carotid artery disease
  • atrial fibrillation (a heart rhythm-related problem)
  • physical inactivity
  • sickle cell disease
  • other heart diseases

Factors that you cannot control are age, family history, gender (female), race (African-Americans), and prior stroke or heart disease. Although these are unmodifiable risk factors, knowing them will give you the motivation to control the ones you can.

There are also some additional factors that are thought to have some link with stroke. They include:

  • Geographic location (more common in the southeastern US)
  • Socioeconomic factors
  • Drug abuse
  • Poor sleep
  • Alcohol abuse

Let’s see what we can do to reduce the risk factors.

Prevention strategies

Prevention aims to decrease the incidence of stroke by modifying a single or multiple risk factors. Three levels of prevention are used.

  1. Primordial prevention: It is the adoption of healthy habits to prevent the emergence of risk factors such as obesity, high blood cholesterol, and smoking.
  2. Primary prevention: It aims to reduce the risk factor profile of the individuals such as physical activity to reduce weight and cholesterol levels.
  3. Secondary prevention: At this level, professionals try to prevent the recurrence of stroke in individuals who already had one.

Here are the behavior modification efforts that are used as the prevention strategy for stroke:


  • Decreased sodium intake
  • Adequate caloric intake
  • Less use of refined carbohydrates and simple sugars
  • Mediterranean, DASH, AHA, or USDA diet.


  • 3-4 times per week

Read here about the 16 Ways To Reach Your Fitness Goals. 

Weight control: 

  • A healthy BMI of 18.5-25kg/m2.
  • For obese individuals, the goal is to achieve less than 30kg/m2

Smoking cessation: 

  • Behavior therapy
  • Counseling
  • Nicotine replacement

3. Lower respiratory infections are the 3rd most deadly diseases in the world.

The infections affecting airways and lungs are termed as lower respiratory infections (lower RTIs). These infections accounted for 3.2 million global deaths in the year 2015.

Common lower RTIs include flu, bronchitis, tuberculosis, pneumonia, and bronchiolitis.

Lower respiratory infections

Symptoms of lower RTIs include:

  • cough
  • fever
  • chest pain
  • tachypnea
  • phlegm and mucus
  • breathlessness and wheezing
  • increased breathing

Patients who have pneumonia may also have some non-respiratory symptoms such as headache, nausea, vomiting, abdominal pain, confusion, and diarrhea.

Risk factors

Risk factors for lower RTIs are given below.

  • Indoor air pollution
  • Smoking (includes passive smoking as well)
  • Weakened immune system
  • Crowding in a household
  • HIV
  • Incomplete immunization in childhood
  • Lack of influenza vaccination
  • Asthma
  • Excessive exposure to lung irritants

Prevention strategies

You can apply the following measures to prevent lower RTIs:

  • Wash your hands before you eat anything and after you have touched your face. Hand washing works best to avoid the transfer of bacteria.
  • Cough and sneeze into a tissue paper. This will help prevent the spread of infection through droplets suspended in the air. Throw away the tissue and wash your hands afterward.
  • Do not share utensils with others. However, they are safe to use after washing.
  • Get pneumococcal vaccination to prevent pneumonia.
  • Get a flu shot every year.
  • Quit smoking as it damages the lungs and makes you prone to respiratory infections.
  • Strengthen your immune system.
  • Keep your house clean.
  • Keep away from crowded housing conditions.

4. Chronic obstructive pulmonary disease (COPD) is the 4th most deadly disease in the world.

COPD is a long-term lung illness that is progressive and makes breathing difficult. From the year 2000 to 2015, 5.6 percent worldwide deaths were secondary to COPD. It’s even more concerning because COPD has no treatment; you can only slow down the progression of the disease.

Risk factors

  • Smoking
  • Passive smoking
  • Long-Term exposure to lung irritants such as air pollution, dust, and chemical fumes
  • A family history of the disease
  • History of respiratory infections such as asthma

Prevention strategies

Prevention lies in the fact that you must quit smoking and avoid bad air that contains lung irritants.

5. Respiratory cancers (trachea, bronchus, and lung) are at # 5.

Although respiratory cancers can affect anyone, but they are more likely to affect people with certain habits or the ones who are exposed to certain elements/conditions.

Risk factors

Risk factors include:

  • Tobacco smoking
  • Cigar smoking
  • Exposure to radioactive elements such as uranium
  • Exposure to asbestos, radon, arsenic, silica, nickel, cadmium, coal products, chloromethyl ethers, beryllium, diesel exhaust and mustard gas.
  • Family history
  • Breathing environmental tobacco smoke
  • Radiation therapy to the chest
  • A family history of lung cancer
  • Smoking along with the use of beta-carotene supplements

Prevention strategies

Avoiding exposure to the environmental pollutants that are risk factors and abstaining from the use of tobacco products are the only preventive strategies at the moment. Leading a healthy lifestyle can also help.

6. Diabetes mellitus is the 6th most deadly disease in the world.

The number of deaths from diabetes have increased from 1 million to 1.6 million during the period 2000-2015.

Diabetes is a common disease that we all have heard about. It refers to a group of diseases that result in too much glucose in the blood either because of lack of insulin production or the failure of your body to use this insulin.

For type I diabetes, the cause is unknown, whereas type 2 diabetes has numerous reasons such as poor diet, sedentary lifestyle, and being overweight.

Related article: Diabetic Diet

Risk factors for type 1 diabetes

Although we don’t know the cause, certain factors are present in the affected individuals. Here’s a list.

  • Family history
  • Environmental factors like exposure to some viral infection
  • Presence of diabetes auto-antibodies
  • Low levels of vitamin D
  • Early exposure to formula milk or cow’s milk (breastfeeding is important!)
  • Geography. Certain countries like Sweden and Finland have higher prevalence than other regions.

Risk factors for pre-diabetes and type 2 diabetes

  • Obesity
  • Sedentary lifestyle
  • Race. Asian-Americans, Blacks, Hispanics, and American Indians have a high risk.
  • Family history
  • Old age
  • Gestational diabetes (diabetes during pregnancy) increases the risk of having pre-diabetes or type 2 diabetes later.
  • High blood pressure
  • Polycystic ovary syndrome
  • Low levels of high-density lipoprotein (good cholesterol)
  • High levels of triglycerides (a type of fat)

Prevention strategies

When you read about the prevention strategies for diabetes, it’s the type 2 diabetes that is being talked about. Most people get type 2 diabetes due to lifestyle factors that are often modifiable. Here’s what you can do to reduce the risk of diabetes:

  • Lose weight because obesity increases the risk of diabetes by seven folds.
  • Stop smoking
  • Reduce your alcohol intake
  • Consume low-carbohydrate diet
  • Cut back on sugary food items
  • Reduce your consumption of refined grains such as white bread.
  • Have a balanced diet by eating a combination of vegetables, nuts, olive oils, fruit, fish, and dairy.
  • Be physically active because inactivity can very much lead to type 2 diabetes.
  • Avoid sugary drinks. Go for tea, coffee, and water instead.
  • Choose good fats such as those found in vegetable oils, seeds, and nuts.
  • Avoid margarine, baked goods, and fried items that are high in bad fats.
  • Try to quit smoking.
  • Avoid processed food.
  • Try these 15 Simple Food Swaps for a Healthy Eating .

7. Alzheimer’s disease and other dementias make up the 7th most deadly diseases in the world.

A disease with no cure and having no way to limit its progression, Alzheimer’s is the 7th most deadly disease in the world.

Although Alzheimer’s and other forms of dementia bring the thought of memory loss, the deaths reported due to these causes are higher than one might think.

Risk factors

  • Old age (>65)
  • family history
  • Down syndrome
  • Gender (females are more prone as compared to males)
  • Existing cognitive impairment
  • History of head trauma
  • Anti-social lifestyle for an extended period
  • Poor diet patterns
  • Unhealthy lifestyle

Prevention strategies

Unfortunately, there is no specific thing you could do to prevent Alzheimer’s. However, the evidence is piling up on the link between our heart’s health and the health of our brains. Therefore, opting for a heart-healthy diet is a sensible option here.

Bottom line

Lifestyle changes can have a significant effect on reducing the global disease burden. You must have noticed that most of these world’s deadliest diseases can be prevented with a healthy lifestyle. Although it is no guarantee that an appropriate lifestyle will implicitly reduce your risk to zero, but the amount of risk that is reduced by adopting these preventive straits is worth considering. Make it your family goal to follow a healthy lifestyle. Read this article (12 Healthy Habits Everyone Should Adopt ASAP ) to know more about healthy habits and lifestyle.

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