Depending on the infection, the body can be affected minimally or severely. In a viral cold infection, the body may feel general discomfort and illness for a short period of time. The Epstein-Barr viral infection, however, can cause the body to become extremely exhausted, which can last for months in some cases. Other infections can cause fevers, pain, and weight loss. Be sure to see your doctor if you have any infection that is bothersome or persistent, or if you don't know what it is.