Firstly, rheumatic fever is a group of delayed sequelae caused by an infection of Group A Streptococci, simply put, it refers to a type of reactive arthritis that appears after an upper respiratory tract infection. It is associated with this streptococcus, and mostly occurs during the cold and humid seasons of winter and spring. It can affect people of any age, but is most commonly seen in children aged 5-14 and adolescents. Therefore, it is not a contagious disease, but rather a set of symptoms, such as fever and joint pain, appearing in individuals with weakened immune systems following an upper respiratory tract infection. Some people may even experience valvular heart disease. However, if treated actively in the early stages, the disease usually does not lead to any long-term consequences, unless it goes untreated or is treated under poor medical conditions, which may then result in rheumatic arthritis and rheumatic heart disease.