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INTRODUCTION

Microbiology

Rickettsiae are obligate intracellular gram-negative coccobacilli and short bacilli usually transmitted by tick, mite, flea, or louse vectors. Except in the case of louse-borne typhus, humans are incidental hosts.

Clinical Manifestations

The clinical manifestations of all the acute rickettsial presentations are similar during the first 5 days and consist of nonspecific symptoms: fever, headache, and myalgias with or without nausea, vomiting, and cough. As the course progresses, clinical manifestations—including occurrence of a macular, maculopapular, or vesicular rash; eschar; pneumonitis; and meningoencephalitis—vary from one disease to another. (See Table 105-1 and details below.)

TABLE 105-1FEATURES OF SELECTED RICKETTSIAL INFECTIONS

TICK- AND MITE-BORNE SPOTTED FEVERS

ROCKY MOUNTAIN SPOTTED FEVER (RMSF)

Epidemiology

Caused by R. rickettsii, RMSF has the highest case-fatality rate of all rickettsial diseases.

  • In the United ...

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