The world is constantly evolving, and so are the diseases that plague it. While some of them may have been eradicated, there are still several diseases that pose a serious threat to human life. 
When it comes to dangerous diseases, there are several that come to mind. However, the most dangerous disease can be subjective based on factors such as mortality rate, spreadability, and available treatments. 

Here are some of the deadliest diseases known to humans:

1. Cardiovascular disease: This is a broad term that refers to a variety of conditions that affect the heart and blood vessels. These include coronary artery disease, heart attacks, and strokes. Cardiovascular disease is the leading cause of death globally, claiming more than 17 million deaths yearly.
2. Cancer: The uncontrolled growth and spread of abnormal cells characterize cancer, which can impact any part of the body. It can affect any part of the body and is responsible for approximately 9.6 million deaths annually.
3. Respiratory illnesses: Respiratory illnesses such as pneumonia, influenza, and COVID-19 can be deadly, especially for those with weakened immune systems or pre-existing health conditions. They claim approximately 3.5 million lives each year.
4. HIV/AIDS: HIV attacks the immune system, leaving the body vulnerable to other infections and diseases. AIDS is the most advanced stage of HIV and is fatal if left untreated. It is responsible for approximately 690,000 deaths annually.

1. Tuberculosis: TB is a bacterial infection that primarily affects the lungs, but it can also affect other parts of the body. It is responsible for approximately 1.5 million deaths each year.
2. Malaria: Malaria, caused by a parasite transmitted by mosquitoes, is a disease that can lead to high fever, chills, and flu-like symptoms. Without proper treatment, it can result in severe complications and even death, claiming around 405,000 lives each year.
3. Alzheimer's disease: Alzheimer's is a progressive neurodegenerative disease that affects memory, thinking, and behaviour. It is the most common cause of dementia and is responsible for approximately 122,000 deaths each year.
4. Diabetes: Diabetes is a chronic condition that affects how the body processes blood sugar. If left untreated, it can lead to serious complications such as heart disease, stroke, kidney disease, and blindness. Diabetes claims approximately 1.6 million lives annually.
5. Dengue fever: Dengue fever is a mosquito-borne viral infection that can cause severe flu-like symptoms. It is responsible for approximately 22,000 deaths each year.
6. Ebola: Ebola is a rare but deadly viral disease that can cause severe bleeding and organ failure. It is responsible for several outbreaks in Africa and has claimed approximately 11,000 lives since its discovery in 1976.

In conclusion, the most dangerous disease can vary based on several factors. However, some of the deadliest diseases in the world include cardiovascular disease, cancer, infectious diseases, and respiratory diseases. While medical advancements have made it possible to treat and manage these diseases, prevention remains the best course of action. Maintaining a healthy lifestyle, getting regular check-ups, and practicing good hygiene can all help prevent the spread of these deadly diseases.