Pediatric Rocky Mountain Spotted Fever Clinical Presentation

Updated: Apr 14, 2021
  • Author: Asif Noor, MD; Chief Editor: Russell W Steele, MD  more...
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The incubation period for Rocky Mountain spotted fever (RMSF) is 2-14 days after the tick bite. A history of tick bite is present in only two thirds of cases.

Symptoms can begin gradually or abruptly. Fever, headache, rash, myalgia, and mental confusion are the major clinical manifestations.

The patient's body temperature usually exceeds 38.8°C (101.8°F). Headache is the most common neurologic manifestation. In older children and adults, the headache may be intractable and may be ongoing day and night. Young children may not complain of headache.

Nausea, vomiting, and abdominal pain may occur. Conjunctival hyperemia and photophobia may be observed.


The rash of Rocky Mountain spotted fever is an important pathognomonic feature of the disease and is present in 80-90% of patients. Rash begins as blanching maculopapular lesions. These lesions become petechial or purpuric in approximately one half of patients, accounting for the disease’s former name of black measles. [9]

The rash first appears peripherally on the wrists and ankles. It spreads centripetally over the next 2-3 days. Involvement of the palms and soles is an important diagnostic feature.

In most patients, rash usually appears by the second or third day. However, it may be delayed until the sixth day.

Early recognition of the blanching macular eruption is vital, because the classic petechial rash does not typically appear until 6 days or so after the initial symptoms become apparent.


Physical Examination

Body temperature exceeds 38.8°C (101.8°F). The patient may have a toxic appearance. The characteristic skin rash is present in 80-90% of infected individuals. Hepatomegaly and splenomegaly are present in approximately 33% of patients. Signs of meningoencephalitis include restlessness, irritability, mental confusion, and delirium.

Meningismus may occur. Findings may include neck stiffness, photophobia, a positive Kernig sign (pain on knee extension when the hip is flexed to 90°), and a positive Brudzinski sign (knee and hip flexion when the neck is flexed).

Ataxia may be present. Spastic paralysis may occur. Sixth nerve palsy may be observed. Muscle tenderness is a common feature.


Complications may include the following:

  • Meningitis

  • Renal failure

  • Pulmonary involvement

  • Liver impairment with development of jaundice

  • Splenomegaly

  • Myocarditis

  • Thrombocytopenia