Rocky Mountain spotted fever is the most important rickettsial disease in this country. Although a petechial component to the rash, the most important diagnostic sign, has long been recognized, the occurrence of thrombocytopenia and other hematologic abnormalities has been noted only recently. Rubio and co-workers1 at the Children's Memorial Hospital in Oklahoma City have recently described 23 cases of Rocky Mountain spotted fever complicated by thrombocytopenia. Most textbooks as well as monographs which discuss the disease state that the blood platelets are within normal limits or make no mention of the occurrence of thrombocytopenia.
These investigators report that a routine search for thrombocytopenia in association with Rocky Mountain spotted fever has been made only in recent years; it has been found in the majority of cases. Of 29 patients recently observed by these workers and in whom a determination of platelets was performed, 21 had thrombocytopenia. Schaffner et al