Fatal viscerotropic Rocky Mountain spotted fever. Report of a case diagnosed by immunofluorescence.

A case of fatal viscerotropic Rocky Mountain spotted fever with virtual absence of cutaneous lesions was diagnosed at autopsy by specific immunofluorescent demonstration of Rickettsia rickettsii in spleen, kidney, epididymis and skin. The clinical presentation was that of insidious onset of fever, renal failure, hypotension, hyponatremia and obtundation over a 10 day period. The patient had respiratory insufficiency, hypocalcemia, increases in creatinine phosphokinase (CPK), serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), lactic dehydrogenase (LDH), alkaline phosphatase, billirubin and serum phosphate, grand mal seizure, myalgia and unremitting shock with death occurring on day 12 of illness. Postmortem examination revealed severe vasculitis with interstitial nephritis and multifocal tubular necrosis, pericholangitis with bile stasis, glial nodules in the brain, multifocal rhabdomyonecrosis, interstitial pneumonitis and mild interstitial myocarditis. Risk factors which this patient shared with other patients with fatal Rocky Mountain spotted fever were failure to recognize a rash, failure to obtain a tick bite history, male sex, black race and age greater than 30 years.