What are some infectious diseases? The answer is simple, a virus makes you ill and then spreads from one person to another. We do not often think about viruses because they do not directly harm our bodies. They can however cause serious problems for the health of those they attack. When you get a cold or a fever, it does not mean you have an illness. Some people call the colds and fever "bacteria" while others use the term "bacterium". What are some infectious diseases that cause epidemics? The two most common are measles and smallpox. Those diseases are easily spread among humans through direct contact. Another example is the swine flu. Like smallpox, the flu is also easily transmitted among humans through direct physical contact. Those two epidemics caused close to 10 million fatalities in the last year alone. What are some of the other infectious diseases? There are many but I will mention just a few. Human immunodeficiency virus, HIV, Hepatitis A virus and Candida infection are all potential causes of AIDS. The HIV/AIDS virus is highly contagious among people. The symptoms of HIV/AIDS include rapid weight loss, frequent fever, swollen lymph glands, joint swelling and extreme fatigue. On the other hand, the hepatitis A virus is the primary cause of cirrhosis, a kidney disease that results in the permanent damage of the liver. What are some of the other types of infectious diseases that are affecting humans? Many of these are still affecting us. Small SARS cases have been discovered in Hong Kong and China. The latest is bird flu. While each disease is different in various ways, the common factor is that all of them are caused by the same virus that we know as AIDS or HIV-AIDS, a group of viruses known collectively as the etiologic agents of modern epidemic. What are some of the environmental risk factors that can lead to the emergence of these epidemics? These are exposure to insecticides, toxic wastes, drugs and chemical toxins, etc. The environmental issues also include chronic exposure to low levels of sunlight, poor sanitation, unhealthy air quality, poor diet, lack of exercise, unhealthy water quality, etc.