Rocky Mountain spotted fever in Adult
The disease is transmitted most commonly via the tick bite of the Dermacentor, Rhipicephalus, or Amblyomma ticks. Mucosal transmission can occur when contaminated by a crushed tick or by tick fecal matter. RMSF occurs over a wide distribution throughout the contiguous United States, but cases are most commonly reported from Arkansas, Missouri, North Carolina, Oklahoma, and Tennessee. RMSF can also be seen in northern Mexico and Central and South America. Over 90% of cases occur during April through September. The disease is more frequent in males and children.
While persons of any ethnicity may be affected, enzyme-linked immunosorbent assay (ELISA) among military personnel has shown higher rates of seropositivity in individuals of African descent. When basing diagnosis on clinical findings paired with serology in a more general population, white individuals had a higher incidence. This discrepancy in serological versus clinical incidence among different ethnic groups may be explained by the difficulty in identifying both ticks and the rash of RMSF in more deeply pigmented skin, which can often delay diagnosis in these patients. Or the rash of RMSF may occur less frequently in patients of African descent (ie, a true variant of disease manifestation and not just a lack of diagnosis by clinicians).
The incidence of RMSF has been steadily increasing to an estimated 2000 cases per year, but the case fatality rates (at least in the United States) have been decreasing (attributed to enhanced recognition and early treatment).
Early clinical manifestations of RMSF include high fever, severe headache, myalgias, nausea, and vomiting. Later manifestations include rash, photophobia, confusion, ataxia, seizures, cough, dyspnea, arrhythmias, jaundice, and severe abdominal pain. Thrombocytopenia and hyponatremia may also be seen. A serious complication of RMSF is rhabdomyolysis. Long-term sequelae include central nervous system deficits and amputations.
RMSF can be prevented by the use of protective clothing and repellants, avoidance of tick-infested areas, and thorough tick inspections after periods of outdoor activity.
A77.0 – Spotted fever due to Rickettsia rickettsii
186772009 – Rocky Mountain spotted fever
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- Measles typically occurs in the winter to spring and has associated symptoms of cough, coryza, conjunctivitis, and Koplik spots.
- Enteroviral infections typically occur in the summer to fall. The fever and rash often appear together. Sick contacts are common.
- Dengue fever, also known as "breakbone fever," has severe arthralgias.
- Vasculitis is marked by palpable purpura rather than petechiae.
- Drug eruptions will have a history of exposure.
- Secondary syphilis can also present with a palm and sole rash; occasionally, the rash imparts a rust-colored hue.
- Gonococcemia may present with asymmetric monoarticular arthritis and a pustular or petechial rash.
- Viral or bacterial enterocolitis presents with nausea and vomiting.
- Acute surgical abdomen has severe abdominal pain.
- Hepatitis presents with jaundice.
- Meningitis has prominent neurological signs.
- Idiopathic thrombocytopenic purpura (ITP) presents with a petechial rash.
- Thrombotic thrombocytopenic purpura (TTP) is characterized by fever, anemia, thrombocytopenia, renal impairment, and neurological deficits.