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When we think about the world’s deadliest diseases we immediately jump to those that are fast-acting and incurable. The ones that get our adrenaline going when we realize we are running out of time, and fast. The sad truth is, many of the deadliest diseases are actually those that progress slowly. In this article, we are going to review the top 5 diseases that have caused the most worldwide deaths, listed by the World Health Organization.

Ischemic heart disease also known as coronary artery disease

The top deadliest disease in the world is CAD, or coronary artery disease. This disease involves the blood vessels around the heart, causing them to become narrowed and thus lessening the blood supply. If left untreated, CAD will lead to chest pain, arrhythmias, and heart failure.

Despite its status as the top deadliest disease, mortality rates have lessened in both the US and many European countries. The main cause for this decline is due to public education, various forms of prevention, and widespread healthcare.

Risk factors for CAD include:

  • High blood pressure
  • High cholesterol
  • Smoking
  • Diabetes
  • Obesity

CAD can be prevented with proper health and sometimes medication.


Strokes take place when an artery in the brain has been either blocked, or broken. The lack of oxygen causes the brain cells to begin dying in mere minutes. Stroke causes numbness, confusion, with issues walking and seeing. An untreated stroke can result in long-term disability.

Risk factors for stroke include:

  • High blood pressure
  • Smoking
  • African-American race
  • Female gender

Stroke can be prevented with proper health and some medications.

Lower Respiratory Infections

Lower respiratory infections typically involve both the airways and lungs. Common illnesses include:

  • Influenza or flu
  • Pneumonia
  • Bronchitis
  • Tuberculosis

Viruses and bacteria both can cause LRI’s, symptoms include breathlessness, wheezing and a tightness in the chest. If left untreated, LRI’s may lead to lung failure and death.

The best preventative one can take against all respiratory infections is to stay vaccinated, wash hands regularly, and stay home when feeling ill.

Chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease, also known as COPD, is typically a lifelong lung disease that progressively gets worse over time and makes breathing difficult. Two types of COPD include chronic bronchitis and emphysema.

Risk factors of COPD

  • Smoking and secondhand smoke
  • Inhaling of lung irritants such as chemical fumes
  • History of respiratory infections

Currently there is no cure for COPD and the progression of this disease can only be slowed by medication.


Trachea, bronchus, and lung cancers

There are a variety of cancers that affect the respiratory system, including cancers of the larynx, bronchus, lungs, and trachea. The most common causes of these cancers include:

  • Smoking and secondhand smoke
  • Environmental toxins
  • House chemicals
  • Household pollutants like molds

Diabetes mellitus

Type 1 and type 2 diabetes affect how the body produces and reacts to insulin. In type 1 diabetes, insulin is unable to be produced, causing those afflicted to have to supplement their insulin through use of pens, pumps, or both. The cause for type 1 diabetes is unknown, as it can affect both children and adults alike.

Type 2 diabetes is when the pancreas either does not produce enough insulin, or the insulin produced is ineffective. Type 2 diabetes has several causes, including an unhealthy diet, obesity, and lack of exercise.