Where’s the Eschar?: Non-Eschar Cases and Eschar Distribution between the Serotypes of Karp, Irie/Kawasaki and Hirano/Kuroki Causing Scrub Typhus in Fukushima, Japan

Background. Rickettsiosis has long been considered as a benign affection. Pathologic mechanisms and prognosis factors of severe forms are incompletely decrypted. In this perspective, we aimed to determine the predictive factors of a severe rickettsiosis (SR). Methods. We conducted a retrospective and prognostic study including all patients with documented rickettsiosis hospitalized between 1993 and 2016. SR was defined by the presence of renal, neurological, cardiac, splenic, and/or pancreatic disorder. Cox proportional hazard regression analysis was used to reveal the independent factors affecting the prognosis of rickettsiosis. Results. We studied 336 cases of rickettsiosis. The mean age was 42.4 ± 16 years and sex ratio (M/F) was 1.1. There were 73 cases with SR (21.7%). Among SR, there were renal forms in 51 cases (69.8%), neurological and/or cardiac involvement in respectively 28 cases (38.3%) and 11 cases (15%). Six patients with SR have required intensive care (8.2% vs. 0.4%; P = 0.001). Advanced age was a risk factor of SR (49.2 ± 17 vs. 40.6 ± 16 years; P < 0.001). Comorbidities were significantly more common in SR (36.4% vs. 23%; P = 0.03; HR = 1.9). Clinical signs associated with SR were purpura (11% vs. 3%; P = 0.01; HR = 3.9), splenomegaly (9.7% vs. 3.8%; P = 0.04; HR = 2.7) and chorioretinitis (9.7% vs. 3.4%; P = 0.037; HR = 3.1). Thrombocytopenia <100 G/L was significantly more frequent in SR (44.4% vs. 27.3%; P = 0.005; HR = 2.1) and serum sodium was significantly lower (132 ± 5 vs. 134 ± 4 mmol/L; P = 0.002). Patients with SR were treated with doxycycline in 51.4% (vs. 66.2%; P = 0.02; HR =0.5). The median-free complications survival was estimated of 20 days (CI95% 15–23 days). Multivariate Cox regression analysis showed that advanced age (HR = 1.02; CI95% 1.008–1.036; P = 0.002) and thrombocytopenia <100 G/L (HR = 1.68; CI95%1.01–2.7; P = 0.042) were the independent prognosis factors of predicting SR. Conclusion. Rickettsiosis remains an emerging infection in our country. Although its natural evolution is often favorable, serious outcomes deserve an intensive and early management based on adequate antimicrobial drugs. Future studies are needed to analyze deeply prognostic profile of rickettsial diseases. Disclosures. All authors: No reported disclosures.