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Rocky Mountain spotted fever can be very difficult to diagnose
in its early stages, even among experienced physicians who are
familiar with the disease.
Patients infected with R. rickettsii generally visit a
physician in the first week of their illness, following an
incubation period of about 5-10 days 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 may include:
- fever
- nausea
- vomiting
- severe headache
- muscle pain
- lack of appetite
Later signs and symptoms include:
- rash
- abdominal pain
- joint pain
- diarrhea
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 first appears 2-5 days after the onset of fever and is
often not present or may be very subtle when the patient is
initially seen by a physician. Younger patients usually develop the
rash earlier than older patients. Most often it begins as small,
flat, pink, non-itchy spots (macules) on the wrists, forearms, and
ankles (Figure 13). 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, and
this type of rash occurs in only 35% to 60% of patients with Rocky
Mountain spotted fever (Figure 14). The rash involves the palms or
soles in as many as 50% to 80% of patients; however, this
distribution may not occur until later in the course of the
disease. As many as 10% to 15% of patients may never develop a
rash.
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Figure 13.
Early (macular) rash on sole of foot |
Figure 14.
Late (petechial) rash on palm and forearm |
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Abnormal laboratory findings seen in patients with Rocky Mountain
spotted fever may include
thrombocytopenia,
hyponatremia, or elevated liver enzyme levels. See
Laboratory Detection for more information on laboratory
confirmation of Rocky Mountain spotted fever.
Rocky Mountain spotted fever can be a very severe illness and
patients often require hospitalization. Because R. rickettsii
infects the cells lining blood vessels throughout the body, severe
manifestations of this disease may involve the respiratory system,
central nervous system, gastrointestinal system, or renal system.
Host factors associated with severe or fatal Rocky Mountain spotted
fever include advanced age, male sex, African-American race, chronic
alcohol abuse, and glucose-6-phosphate dehydrogenase (G6PD)
deficiency. Deficiency of G6PD is a sex-linked genetic condition
affecting approximately 12% of the U.S. African-American male
population; deficiency of this enzyme is associated with a high
proportion of severe cases of Rocky Mountain spotted fever. This is
a rare clinical course that is often fatal within 5 days of onset of
illness.
Long-term health problems following acute Rocky Mountain spotted
fever infection include partial paralysis of the lower extremities,
gangrene requiring amputation of fingers, toes, or arms or legs,
hearing loss, loss of bowel or bladder control, movement disorders,
and language disorders. These complications are most frequent in
persons recovering from severe, life-threatening disease, often
following lengthy hospitalizations.Other Pages with
information on Rocky Mountain Spotted Fever:
Rocky
Mountain Spotted Fever - History
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Rocky Mountain Spotted Fever Overview
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Rocky
Mountain Spotted Fever The Organism
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Rocky Mountain Spotted Fever
Epidemiology
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Rocky Mountain Spotted Fever
Signs and Symptoms
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Rocky Mountain spotted fever
Detection
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Rocky Mountain Spotted Fever
Treatment
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Rocky Mountain Spotted Fever
Prevention and Control
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