We read the article “Evidence of Rickettsia prowazekii infections in the United States” (Am. J. Trop. Med. Hyg., 29: 277–284, 1980) with interest, as Patient No. 6 in the article was reported to the Center for Disease Control by us. We also read the article with concern, as we are convinced that our patient had murine typhus—not epidemic typhus as reported in the article.
Clinically, seven of the eight patients had mild illness, including two patients (Nos. 3 and 6) who never received effective antimicrobial therapy. Additionally, three of the patients (Nos. 3, 6, and 7) had definite exposure to rats and/or mice. These data strongly implicate murine typhus—not epidemic typhus—as the disease process in some, if not all, of the patients. Finally, the only proven vector of epidemic typhus, the body louse, was never identified among the patients.
It would appear that the differential absorption of rickettsial antigens constituted the only reason to discard a diagnosis of murine typhus.