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Rocky Mountain spotted fever (RMSF), also known as blue disease, is the most lethal and most frequently reported rickettsial illness in the United States. It has been diagnosed throughout the Americas. Some synonyms for Rocky Mountain spotted fever in other countries include “tick typhus,” “Tobia fever” (Colombia), “São Paulo fever” or “''febre maculosa''” (Brazil), and “''fiebre manchada''” (Mexico). It is distinct from the viral tick-borne infection, Colorado tick fever. The disease is caused by ''Rickettsia rickettsii'', a species of bacterium that is spread to humans by ''Dermacentor'' ticks. Initial signs and symptoms of the disease include sudden onset of fever, headache, and muscle pain, followed by development of rash. The disease can be difficult to diagnose in the early stages, and without prompt and appropriate treatment it can be fatal. The name “Rocky Mountain spotted fever” is something of a misnomer. The disease was first identified in the Rocky Mountain region, but beginning in the 1930s, medical researchers realized that it occurred in many other areas of the United States. It is now recognized that the disease is broadly distributed throughout the contiguous United States and occurs as far north as Canada and as far south as Central America and parts of South America. Between 1981 and 1996, the disease was reported from every state of the United States except for Hawaii, Vermont, Maine, and Alaska. Rocky Mountain spotted fever remains a serious and potentially life-threatening infectious disease. Despite the availability of effective treatment and advances in medical care, approximately three to five percent of patients who become ill with Rocky Mountain spotted fever die from the infection. However, effective antibiotic therapy has dramatically reduced the number of deaths caused by Rocky Mountain spotted fever. Before the discovery of tetracycline and chloramphenicol during the latter 1940s, as many as 30 percent of persons infected with ''R. rickettsii'' died. ==Signs and symptoms== Spotted fever can be very difficult to diagnose in its early stages, and even experienced physicians who are familiar with the disease find it hard to detect. People infected with ''R. rickettsii'' usually notice symptoms following an incubation period of one to two weeks after a tick bite. The early clinical presentation of Rocky Mountain spotted fever is nonspecific and may resemble a variety of other infectious and non-infectious diseases. Initial symptoms: *Fever *Nausea *Emesis (vomiting) *Severe headache *Muscle pain *Lack of appetite *Parotitis in some cases (somewhat rare) Later signs and symptoms: *Maculopapular rash *Petechial rash *Abdominal pain *Joint pain *Forgetfulness The classic triad of findings for this disease are fever, rash, and history of tick bite. However, this combination is often not identified when the patient initially presents for care. The rash has a centripetal, or "inward" pattern of spread, meaning it begins at the extremities and courses towards the trunk. The rash first appears two to five days after the onset of fever, and it is often quite subtle. Younger patients usually develop the rash earlier than older patients. Most often the rash begins as small, flat, pink, non-itchy spots (macules) on the wrists, forearms, and ankles. These spots turn pale when pressure is applied and eventually become raised on the skin. The characteristic red, spotted (petechial) rash of Rocky Mountain Spotted Fever is usually not seen until the sixth day or later after onset of symptoms, but this type of rash occurs in only 35 to 60 percent of patients with Rocky Mountain spotted fever. The rash involves the palms or soles in as many as 80 percent of the patients. However, this distribution may not occur until later on in the course of the disease. As many as 15 percent of patients may never develop a rash. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Rocky Mountain spotted fever」の詳細全文を読む スポンサード リンク
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