After hearing about a contagious disease, one is often worried. This is because these contagious diseases can easily spread to people around the infected person. Children are one of the most common victims of contagious diseases. All because they tend to remain in proximity to other children at crèche, nursery's and schools. They also have a weak and developing immune system that may not be able to fight each and every infection it encounters. Infections that are caused by bacteria, virus, fungi and protozoans are generally termed as contagious diseases. These organisms are easily passed on from people to people through direct or indirect contact. There are some very common contagious diseases that tend to infect people every other day. However, not all develop an infection, especially when they are healthy and their immune system is strong. List of Most Common Contagious Infections There is a long list of contagious diseases that affect people of all ages around the world. When a person catches an infection, he or she may become contagious, especially in case of a bacterial or viral infection. Common Cold One of the most common highly contagious infections is common cold. It is one of the main reasons many children and adults remain absent from school or work. Common cold is a viral infection caused by parainfluenza virus, adenovirus, echovirus, and many other viruses. The viral agents spread through nasal discharge and droplets after an infected person sneezes or coughs. It can even spread through surface contact with a contaminated object. Influenza Another common respiratory disease is influenza, commonly known as flu. It affects about 20% of patients in United States who suffer from flu in a year. It leads to fever, cough, runny nose, vomiting, diarrhea, nausea, fatigue and muscle aches. This disease spreads through nasal droplets from coughing and sneezing. Conjunctivitis This is one of the most common contagious eye disease in preschoolers. Also, called pink eye, conjunctivitis can be caused by a bacterial or viral agent. It leads to inflammation of the membrane covering the white of the eye. This leads to redness, swelling, watery discharge and visual problems at times. This condition may affect any person of any age, but rate of transmission is high in children. Because they remain in close contact with other children and do not understand what may irritate their eye and cause an infection. Chickenpox Another common contagious disease in children that leads to a severe rash on the body. This contagious diseases is caused by varicella zoster virus that spreads through nasal droplets spread by sneezing, coughing and coming in contact with contaminated objects. It leads to fluid filled lesions on the body that are very itchy. The child may even develop fever due to the rash. There is no specific treatment for chickenpox and the infection resolves on its own after about 6 days of the last rashes appeared on the body. This is a very contagious infection and any child or adult infected should stay away from crowded areas and avoid traveling. Cryptosporidiosis One of the most contagious waterborne diseases in United States is cryptosporidiosis. It is caused by a parasite that spreads through drinking contaminated water with human or animal feces. It leads to stomach cramps, slight fever and diarrhea. Cholera Another waterborne contagious disease that affects about 200,000 people worldwide every year is cholera. It is caused by a bacterium called Vibrio cholerae. Symptoms of cholera include copious diarrhea, vomiting and leg cramps. In some severe cases, it can lead to death due to dehydration. Ringworm This is a common fungal skin infection that causes ring shape patches on the skin. Although named ring'worm', due to its appearance on the skin, it is caused by a fungus. It causes pink, round patches on skin of the face, arms, legs and other parts of the body. Close body contact leads to transmission of this fungal infection to the healthy individual. Tuberculosis Tuberculosis or TB is caused by a bacterium Mycobacterium tuberculosis in humans. This bacterium attacks the lungs as it spreads through air. Coughing or sneezing by an infected individual causes the bacteria to become airborne and lead to infection in a healthy individual. If left untreated it leads to death in 50% of the cases. The characteristic symptoms of TB include chronic cough, blood tinged sputum, fever and excessive weight loss. HIV/AIDS One of the most common and dangerous contagious diseases today is HIV/AIDS. It is caused by transmission of Human Immunodeficiency Virus (HIV). This virus can be contracted by contaminated blood transfusions, use of contaminated injection needles, unprotected sex, transmission of body fluids during a sexual intercourse. However, HIV/AIDS does NOT spread through hand shakes, sharing of clothes, utensils, sitting close to an infected person, etc. You can read in detail about how is HIV transmitted and overcome some common misnomer about the disease. Other common contagious diseases include mumps, measles, scarlet fever, whooping cough, malaria, typhoid, etc. As long as there are microorganisms around us, each and every one is susceptible to a contagious disease. We can take some precautions like washing hands frequently, covering our nose and mouth when coughing or sneezing, avoiding sharing of towels and other personal items, etc. A healthy diet and lifestyle will ensure the body stays strong and is able to fight off any invading organism. A few precautions and one can avoid developing a serious infection to some extent.