The Worlds most Common Diseases

There are thousands of disease in the world. Some of these diseases are rare while there are others which are common. In many cases, the most common diseases are the ones which are very dangerous. Diseases such as HIV/AIDS, pneumonia, tuberculosis, lung cancer and syphilis are common because every year a lot of people contract the disease and the rate of death is high or it keeps increasing.

All the diseases that are known are categorized into 10 major groups. They are: viral, bacterial, cancer, autoimmune, sexually transmitted, digestive, heart, blood, thyroid and nerve.

However, having known diseases are categorized into 10 major groups or there are 10 major types of diseases, it is imperative for a person to understand the meaning of disease. What is disease? Biology-Online defines disease as “An abnormal condition of an organism which interrupts the normal bodily functions that often lead to feeling of pain and weakness, and usually associated with symptoms and signs.”

Disease is also defined as “A pathological condition in which the normal functioning of an organism or body is impaired or disrupted resulting in extreme pain, dysfunction, distress, or death.”

The list below is a brief description or overview of the common diseases in the world which also happen to be the the world’s most dangerous diseases.


Malaria is a disease spread by a female mosquito, Anopheles. When it bites an infected person, the mosquito ingests the malaria parasite and after a week, it is capable of transmitting the disease to a non-infected person.

The most affected regions in the world are developing countries especially Sub-Saharan Africa. The elderly, pregnant women and children under the age of five years are the most vulnerable groups. When it affects pregnant women, it may lead to spontaneous abortion and miscarriage.

It is estimated by World Health Organization (WHO) that a half of the world’s population is at risk of malaria. The World Health Organization (WHO) states, “In 2010, there were about 219 million malaria cases (with uncertainty range of 154 million to 289 million) and an estimated 660,000 malaria deaths (with uncertainty range of 490,000 to 836,000).”

In Africa a child dies of malaria every 3 seconds (one out of five children).

The symptoms of malaria include: headache, muscle aches, stomach pains, fever, nausea, vomiting and diarrhea. If immediate or early medication is not sought, it can be fatal. The advanced symptoms of malaria are: anemia, paralysis, comma, kidney failure, jaundice and convulsion.


AIDS is caused by HIV virus. The HIV virus damages the white blood cells responsible for fighting diseases. When many of the defense cells – white blood cells – have been destroyed the body becomes weak and vulnerable to opportunistic diseases. Opportunistic diseases are diseases which take advantage of the lowered body immunity. Examples of opportunistic diseases are: pneumonia, tuberculosis and diarrhea. 

The symptoms of HIV/AIDS include: swollen glands, weight loss, white spots on the tongue and mouth, night sweats, tiredness, shortness of breath, recurrent herpes zoster, skin diseases, chronic diarrhea and fever lasting for more than one month.

HIV/AIDS is spread through sexual contact, blood transfusion, organ transplant from infected donors, mother-to-child transmission and sharing of needles or sharp objects with an infected person. It is not transmitted through playing together, shaking hands, hugging, sharing towels, utensils, bathroom and toilet seats.

Currently, 34 million people are infected with HIV/AIDS. Sub-Saharan region leads in the number of the most infected.


Tuberculosis (TB) is a common and deadly infectious disease caused by mycobacteria. It attacks mostly the lungs (pulmonary TB), though it also affects the central nervous system, circulatory system, bones and joints, skin and gastrointestinal system.

The symptoms of TB are: loss of weight, poor appetite, chronic cough, coughing up blood, pain in the chest, night sweats, jaundice, nausea and vomiting.

The most affected people are those whose immune system is weak, such as people with HIV.

According to WHO, TB is second to HIV/AIDS as the greatest killer disease worldwide. “In 2011, 8.7 million people fell ill with TB and 1.4 million died from TB.”

Lung Cancer

Lung cancer kills more people than colon, prostate, ovarian and breast cancer combined.

It is mostly caused by smoking cigarettes.

The symptoms of lung cancer don’t appear immediately. They include chronic coughing, chest pains, coughing up blood, fatigue and swelling in the neck and face.

People who do not smoke are also vulnerable to contracting the disease. This is mostly the case with people who live in the same room or work at the same place with a person who always smokes. This is known as second-hand smoke.

Globocan notes that in the year 2008 about 1.6 million new cases were reported. “It was also the most common cause of death from cancer, with 1.38 million deaths (18.2% of the total).


Syphilis is a contagious disease. It is transmitted from one person to another through direct contact with syphilis sores. The sores may be located on the genitals, vagina, anus or in the rectum.

It is mostly transmitted through sexual contact.

When talking about sexual contact, it implies vaginal, anal or oral sex.

Pregnant women can pass the disease to their unborn babies. During the delivery, the baby may die prior to delivery or shortly after delivery. There are instances when the baby shows no signs and symptoms after delivery. However, if the baby is not treated early, it may lead to serious health problems e.g. deafness and seizure, and possibly death.

If adults are not treated early, it may lead to paralysis, blindness, dementia and numbness. The disease may also damage internal organs such as the brain, heart, liver and blood vessels. It may also result to death.

According to Besttopers, in 2011, an estimated 12.2 million people were diagnosed with the disease, and every year, 157,000 deaths occur.