Disease the time between infection and the appearance of symptoms. The latency period is the time between infection and the ability of the disease to spread to another person, which may precede, follow, or be simultaneous with the appearance of symptoms. Some viruses also exhibit a dormant phase, called viral latency, in which the virus hides in the body in an inactive state. For example, varicella zoster virus causes chickenpox in the acute phase; after recovery from chickenpox, the virus may remain dormant in nerve cells for many years, and later cause herpes zoster (shingles). Diseases may be classified by cause,
Reactive airway disease Reactive airway disease Reactive airway disease is a general term used by many physicians to label patients with symptoms similar to those of asthma. It is most commonly used when a physician is hesitant about formally diagnosing a patient with asthma, which is most prevalent in the pediatric setting for a variety of reasons. While some physicians may use RAD and asthma synonymously, this causes controversy, since RAD can not be used as a real diagnosis for physicians. An exact definition of the condition does not exist. Individuals that are typically labeled as having reactive airway disease, or RAD, generally