Rubella, also known as German Measles, is a contagious infectious disease caused by the Rubella virus, presenting symptoms similar to measles and generally having a mild course. The disease is characterized by fever, a measles-like rash, and swelling of the lymph nodes (lymphadenopathy). It is particularly common in children aged 5-9 years. The virus settles in the upper respiratory tract via droplet transmission, then multiplies in the lymph nodes, leading to a rash. If infection occurs during pregnancy, it can cause severe harm to the unborn baby.