A condition that affects fewer than 5 people per 10,000 people in the EU is considered rare. This may appear insignificant, yet it represents around 246,000 people. The vast majority of the people suffering from much rarer conditions affects one in 100,000 or more persons. Infectious diseases are conditions brought on by bacteria, viruses, fungus, or parasites. Our bodies are home to a variety of microbes. In most cases, they're innocuous or even beneficial. However, some microbes can cause disease under certain circumstances. Some infectious diseases are contagious and can be spread from one person to the next. Insects and other animals can spread several diseases. Microscopic organisms cross the body's natural barriers and multiply, causing a variety of symptoms ranging from minor to fatal. Despite the eradication or control of many infectious diseases, humanity remains vulnerable to a wide spectrum of novel and resurgent infections.