Rickettsialpox Clinical Presentation

Updated: Jun 30, 2017
  • Author: Pradeep Kumar Mada, MD, MRCP(UK); Chief Editor: Mark R Wallace, MD, FACP, FIDSA  more...
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Presentation

History

Following a mite bite, R akari proliferates locally in the skin. After 7-10 days, a firm, red papule 1-1.5 cm in diameter appears; in a few days, it vesiculates with a surrounding area of erythema. The lesion then ulcerates, forms an eschar, and slowly heals.

About 3-7 days after the appearance of the skin lesion, rickettsialpox may manifest as a sudden onset of high fever, chills, sore throat, rigor and profuse sweating, myalgias (especially backache), anorexia, and photophobia. Untreated, fever may last a week. Vertigo, conjunctival injection, cough, rhinorrhea, nausea, and vomiting sometimes occur. Headaches and neck stiffness may be severe. Regional lymphadenopathy at the draining site of the eschar is common, and generalized lymphadenopathy has also been reported. Lymphangitis is not a feature of rickettsialpox.

Approximately 2-3 days after the onset of systemic symptoms, the generalized papulovesicular rash of rickettsialpox erupts. This can involves palms and soles and is occasionally accompanied by an oropharyngeal enanthem. This rash typically lasts a week.

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Physical

Patients with rickettsialpox may have high fever fluctuating between 101-104ºF.

The maculopapulovesicular exanthema is usually composed of 20-40 lesions but may range from 5-100. Features are as follows:

  • The lesions typically begin as papules with subsequent vesiculation, but may remain avesicular.
  • Lesions are usually scattered on the face, trunk, and extremities with no particular sequence of involvement. Patients may present with lesions on the tongue, buccal mucosa, and pharynx.
  • Lesions may also be present on palms and soles.
  • The lesions are typically asymptomatic but can be pruritic.
  • Rashes last a week. Scabs form but do not leave scars.

At the time of presentation, an eschar is present in at least 95% of affected individuals. The mite bite is painless and begins as an erythematous papule, which develops into a tense vesicle that ruptures to form a dark crust with surrounding induration. More than one eschar may be present. Features are as follows:

  • Mite bites can occur on any part of the body, including the hands, feet, face, and angle of the mouth (labial commissure). They do occur in covered areas.
  • Regional adenopathy may be present and is usually tender.
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Causes

Rickettsialpox is caused by R akari and was first described in 1946.

Rickettsialpox is sporadically observed in many urban centers of the United States. The bloodsucking mite L sanguineus is the vector, and mice (typically M musculus) and other rodents are the reservoir.

When murine hosts are scarce, A sanguineus will bite humans.

No human-to-human transmission occurs.

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