A Febrile Illness with Generalized Papular Rash Involving the Palms and Soles

Abstract

Diagnosis: Rickettsia honei infection. A provisional diagnosis of rickettsial illness was made at transfer of the patient to our medical center, and oral doxycycline administered at an initial dose of 200 mg followed by 100 mg twice per day for 1 week was prescribed. Rapid plasma reagin tests and blood cultures had negative results. Results of serial rickettsial serological testing demonstrated a striking increase in antibody titer to R. honei (table 1). Rickettsial PCR and culture performed at the Australian Rickettsial Reference Laboratory (Geelong, Australia) on a blood specimen collected at day 14 of illness (before specific treatment was initiated) had negative results. A number of new spotted fever group rickettsiae have been identified in the past 3 decades. Infection due to R. honei in Australia was first described among residents of Flinders Island in Bass Strait (separating mainland Australia from Tasmania) 15 years ago [1], but in the last 3 years, this infection has also been recognized in southern mainland Australia [2, 3]. The evidence suggests that the principal vector of R. honei infection is the parasitic tick Aponomma hydrosauri, which has a variety of reptile hosts, including members of the skink (Scincidae) family (of which blue-tongue lizards are a member) [4]. The clinical illness is generally characteristic, with fever, myalgias, headaches, and rash. The rash may vary in nature, and the palms and soles are variably involved (figure 1). Eschars and regional lymphadenopathy are inconsistently found. Definitive